:: GLIB_000 semantic presentation

begin

registration
cluster Relation-like NAT -defined Function-like finite for set ;
existence
 ex b1 being Function st
( b1 is finite & b1 is NAT -defined )
proof
take  {} ; ::_thesis: ( {} is finite & {} is NAT -defined )
thus  {} is finite ; ::_thesis: {} is NAT -defined
thus  dom {} c= NAT ; :: according to RELAT_1:def_18 ::_thesis: verum
end;
end;

definition
mode GraphStruct is NAT -defined finite Function;
end;

definition
func VertexSelector  ->  Element of NAT  equals :: GLIB_000:def 1
1;
coherence
 1 is Element of NAT ;
func EdgeSelector  ->  Element of NAT  equals :: GLIB_000:def 2
2;
coherence
 2 is Element of NAT ;
func SourceSelector  ->  Element of NAT  equals :: GLIB_000:def 3
3;
coherence
 3 is Element of NAT ;
func TargetSelector  ->  Element of NAT  equals :: GLIB_000:def 4
4;
coherence
 4 is Element of NAT ;
end;

:: deftheorem  defines VertexSelector GLIB_000:def_1_:_
 VertexSelector = 1;

:: deftheorem  defines EdgeSelector GLIB_000:def_2_:_
 EdgeSelector = 2;

:: deftheorem  defines SourceSelector GLIB_000:def_3_:_
 SourceSelector = 3;

:: deftheorem  defines TargetSelector GLIB_000:def_4_:_
 TargetSelector = 4;

definition
func _GraphSelectors  ->  non empty Subset of NAT equals :: GLIB_000:def 5
{VertexSelector,EdgeSelector,SourceSelector,TargetSelector};
coherence
 {VertexSelector,EdgeSelector,SourceSelector,TargetSelector} is non empty Subset of NAT ;
end;

:: deftheorem  defines _GraphSelectors GLIB_000:def_5_:_
 _GraphSelectors = {VertexSelector,EdgeSelector,SourceSelector,TargetSelector};

definition
let G be GraphStruct;
func the_Vertices_of G ->  set  equals :: GLIB_000:def 6
G . VertexSelector;
coherence
 G . VertexSelector is set ;
func the_Edges_of G ->  set  equals :: GLIB_000:def 7
G . EdgeSelector;
coherence
 G . EdgeSelector is set ;
func the_Source_of G ->  set  equals :: GLIB_000:def 8
G . SourceSelector;
coherence
 G . SourceSelector is set ;
func the_Target_of G ->  set  equals :: GLIB_000:def 9
G . TargetSelector;
coherence
 G . TargetSelector is set ;
end;

:: deftheorem  defines the_Vertices_of GLIB_000:def_6_:_
 for G being GraphStruct holds the_Vertices_of G = G . VertexSelector;

:: deftheorem  defines the_Edges_of GLIB_000:def_7_:_
 for G being GraphStruct holds the_Edges_of G = G . EdgeSelector;

:: deftheorem  defines the_Source_of GLIB_000:def_8_:_
 for G being GraphStruct holds the_Source_of G = G . SourceSelector;

:: deftheorem  defines the_Target_of GLIB_000:def_9_:_
 for G being GraphStruct holds the_Target_of G = G . TargetSelector;

definition
let G be GraphStruct;
attrG is [Graph-like]  means :Def10: :: GLIB_000:def 10
( VertexSelector in dom G & EdgeSelector in dom G & SourceSelector in dom G & TargetSelector in dom G & the_Vertices_of G is non empty set & the_Source_of G is Function of (the_Edges_of G),(the_Vertices_of G) & the_Target_of G is Function of (the_Edges_of G),(the_Vertices_of G) );
end;

:: deftheorem Def10 defines [Graph-like] GLIB_000:def_10_:_
 for G being GraphStruct holds
( G is [Graph-like] iff ( VertexSelector in dom G & EdgeSelector in dom G & SourceSelector in dom G & TargetSelector in dom G & the_Vertices_of G is non empty set & the_Source_of G is Function of (the_Edges_of G),(the_Vertices_of G) & the_Target_of G is Function of (the_Edges_of G),(the_Vertices_of G) ) );

registration
cluster Relation-like NAT -defined Function-like finite [Graph-like] for set ;
existence
 ex b1 being GraphStruct st b1 is [Graph-like]
proof
set V = {1};
set E = {} ;
reconsider S = {} as Function of {},{1} by RELSET_1:12;
set G = <*{1},{},S,S*>;
 len <*{1},{},S,S*> = 4 by FINSEQ_4:76;
then A1: dom <*{1},{},S,S*> = Seg 4 by FINSEQ_1:def_3;
reconsider G = <*{1},{},S,S*> as GraphStruct ;
A2: ( SourceSelector in dom G & TargetSelector in dom G ) by A1, FINSEQ_1:1;
A3: ( the_Vertices_of G = {1} & the_Edges_of G = {} ) by FINSEQ_4:76;
A4: ( the_Source_of G = S & the_Target_of G = S ) by FINSEQ_4:76;
 ( VertexSelector in dom G & EdgeSelector in dom G ) by A1, FINSEQ_1:1;
then  G is [Graph-like] by A3, A4, A2, Def10;
hence  ex b1 being GraphStruct st b1 is [Graph-like] ; ::_thesis: verum
end;
end;

definition
mode _Graph is [Graph-like] GraphStruct;
end;

registration
let G be _Graph;
cluster the_Vertices_of G ->  non empty ;
coherence
 not the_Vertices_of G is empty by Def10;
end;

definition
let G be _Graph;
:: original: the_Source_of
redefine func the_Source_of G ->  Function of (the_Edges_of G),(the_Vertices_of G);
coherence
 the_Source_of G is Function of (the_Edges_of G),(the_Vertices_of G) by Def10;
:: original: the_Target_of
redefine func the_Target_of G ->  Function of (the_Edges_of G),(the_Vertices_of G);
coherence
 the_Target_of G is Function of (the_Edges_of G),(the_Vertices_of G) by Def10;
end;

definition
let V be non empty set ;
let E be set ;
let S, T be Function of E,V;
func createGraph (V,E,S,T) ->  _Graph equals :: GLIB_000:def 11
<*V,E,S,T*>;
coherence
 <*V,E,S,T*> is _Graph
proof
set G = <*V,E,S,T*>;
 len <*V,E,S,T*> = 4 by FINSEQ_4:76;
then A1: dom <*V,E,S,T*> = Seg 4 by FINSEQ_1:def_3;
reconsider G = <*V,E,S,T*> as GraphStruct ;
A2: ( SourceSelector in dom G & TargetSelector in dom G ) by A1, FINSEQ_1:1;
A3: ( the_Vertices_of G = V & the_Edges_of G = E ) by FINSEQ_4:76;
A4: ( the_Source_of G = S & the_Target_of G = T ) by FINSEQ_4:76;
 ( VertexSelector in dom G & EdgeSelector in dom G ) by A1, FINSEQ_1:1;
hence  <*V,E,S,T*> is _Graph by A3, A4, A2, Def10; ::_thesis: verum
end;
end;

:: deftheorem  defines createGraph GLIB_000:def_11_:_
 for V being non empty set
for E being set
for S, T being Function of E,V holds createGraph (V,E,S,T) = <*V,E,S,T*>;

definition
let G be GraphStruct;
let n be Nat;
let x be set ;
funcG .set (n,x) ->  GraphStruct equals :: GLIB_000:def 12
G +* (n .--> x);
coherence
 G +* (n .--> x) is GraphStruct
proof
set IT = G +* (n .--> x);
A1: dom (n .--> x) = {n} by FUNCOP_1:13;
 n in NAT by ORDINAL1:def_12;
then A2: {n} c= NAT by ZFMISC_1:31;
 ( dom (G +* (n .--> x)) = (dom G) \/ (dom (n .--> x)) & dom G c= NAT ) by FUNCT_4:def_1;
then  dom (G +* (n .--> x)) c= NAT by A2, A1, XBOOLE_1:8;
hence  G +* (n .--> x) is GraphStruct by RELAT_1:def_18; ::_thesis: verum
end;
end;

:: deftheorem  defines .set GLIB_000:def_12_:_
 for G being GraphStruct
for n being Nat
for x being set holds G .set (n,x) = G +* (n .--> x);

Lm1:  for GS being GraphStruct holds
( GS is [Graph-like] iff ( _GraphSelectors c= dom GS & not the_Vertices_of GS is empty & the_Source_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) & the_Target_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) ) )
proof
let GS be GraphStruct; ::_thesis: ( GS is [Graph-like] iff ( _GraphSelectors c= dom GS & not the_Vertices_of GS is empty & the_Source_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) & the_Target_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) ) )
now__::_thesis:_(_(_VertexSelector_in_dom_GS_&_EdgeSelector_in_dom_GS_&_SourceSelector_in_dom_GS_&_TargetSelector_in_dom_GS_implies__GraphSelectors_c=_dom_GS_)_&_(__GraphSelectors_c=_dom_GS_implies_(_VertexSelector_in_dom_GS_&_EdgeSelector_in_dom_GS_&_SourceSelector_in_dom_GS_&_TargetSelector_in_dom_GS_)_)_)
hereby  ::_thesis: ( _GraphSelectors c= dom GS implies ( VertexSelector in dom GS & EdgeSelector in dom GS & SourceSelector in dom GS & TargetSelector in dom GS ) )
assume  ( VertexSelector in dom GS & EdgeSelector in dom GS & SourceSelector in dom GS & TargetSelector in dom GS ) ; ::_thesis: _GraphSelectors c= dom GS
then  for x being set st x in _GraphSelectors holds
x in dom GS by ENUMSET1:def_2;
hence  _GraphSelectors c= dom GS by TARSKI:def_3; ::_thesis: verum
end;
A1: ( VertexSelector in _GraphSelectors & EdgeSelector in _GraphSelectors ) by ENUMSET1:def_2;
A2: ( SourceSelector in _GraphSelectors & TargetSelector in _GraphSelectors ) by ENUMSET1:def_2;
assume  _GraphSelectors c= dom GS ; ::_thesis: ( VertexSelector in dom GS & EdgeSelector in dom GS & SourceSelector in dom GS & TargetSelector in dom GS )
hence  ( VertexSelector in dom GS & EdgeSelector in dom GS & SourceSelector in dom GS & TargetSelector in dom GS ) by A1, A2; ::_thesis: verum
end;
hence  ( GS is [Graph-like] iff ( _GraphSelectors c= dom GS & not the_Vertices_of GS is empty & the_Source_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) & the_Target_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) ) ) by Def10; ::_thesis: verum
end;

registration
let G be _Graph;
clusterG | _GraphSelectors ->  [Graph-like] ;
coherence
 G | _GraphSelectors is [Graph-like]
proof
now__::_thesis:_for_x_being_set_st_x_in__GraphSelectors_holds_
x_in_dom_G
let x be set ; ::_thesis: ( x in _GraphSelectors implies x in dom G )
assume  x in _GraphSelectors ; ::_thesis: x in dom G
then  ( x = VertexSelector or x = EdgeSelector or x = SourceSelector or x = TargetSelector ) by ENUMSET1:def_2;
hence  x in dom G by Def10; ::_thesis: verum
end;
then A1: _GraphSelectors c= dom G by TARSKI:def_3;
set G2 = G | _GraphSelectors;
 VertexSelector in _GraphSelectors by ENUMSET1:def_2;
then A2: the_Vertices_of (G | _GraphSelectors) = the_Vertices_of G by FUNCT_1:49;
 EdgeSelector in _GraphSelectors by ENUMSET1:def_2;
then A3: the_Edges_of (G | _GraphSelectors) = the_Edges_of G by FUNCT_1:49;
 TargetSelector in _GraphSelectors by ENUMSET1:def_2;
then A4: the_Target_of (G | _GraphSelectors) = the_Target_of G by FUNCT_1:49;
 SourceSelector in _GraphSelectors by ENUMSET1:def_2;
then A5: the_Source_of (G | _GraphSelectors) = the_Source_of G by FUNCT_1:49;
dom (G | _GraphSelectors) = (dom G) /\ _GraphSelectors by RELAT_1:61
.= _GraphSelectors by A1, XBOOLE_1:28 ;
hence  G | _GraphSelectors is [Graph-like] by A2, A3, A5, A4, Lm1; ::_thesis: verum
end;
end;

definition
let G be _Graph;
let x, y, e be set ;
prede Joins x,y,G means :Def13: :: GLIB_000:def 13
( e in the_Edges_of G & ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) );
end;

:: deftheorem Def13 defines Joins GLIB_000:def_13_:_
 for G being _Graph
for x, y, e being set holds
( e Joins x,y,G iff ( e in the_Edges_of G & ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) ) );

definition
let G be _Graph;
let x, y, e be set ;
prede DJoins x,y,G means :Def14: :: GLIB_000:def 14
( e in the_Edges_of G & (the_Source_of G) . e = x & (the_Target_of G) . e = y );
end;

:: deftheorem Def14 defines DJoins GLIB_000:def_14_:_
 for G being _Graph
for x, y, e being set holds
( e DJoins x,y,G iff ( e in the_Edges_of G & (the_Source_of G) . e = x & (the_Target_of G) . e = y ) );

definition
let G be _Graph;
let X, Y, e be set ;
prede SJoins X,Y,G means :Def15: :: GLIB_000:def 15
( e in the_Edges_of G & ( ( (the_Source_of G) . e in X & (the_Target_of G) . e in Y ) or ( (the_Source_of G) . e in Y & (the_Target_of G) . e in X ) ) );
prede DSJoins X,Y,G means :Def16: :: GLIB_000:def 16
( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in Y );
end;

:: deftheorem Def15 defines SJoins GLIB_000:def_15_:_
 for G being _Graph
for X, Y, e being set holds
( e SJoins X,Y,G iff ( e in the_Edges_of G & ( ( (the_Source_of G) . e in X & (the_Target_of G) . e in Y ) or ( (the_Source_of G) . e in Y & (the_Target_of G) . e in X ) ) ) );

:: deftheorem Def16 defines DSJoins GLIB_000:def_16_:_
 for G being _Graph
for X, Y, e being set holds
( e DSJoins X,Y,G iff ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in Y ) );

Lm2:  for G being _Graph
for e, x, y being set holds
( e Joins x,y,G iff ( e DJoins x,y,G or e DJoins y,x,G ) )
proof
let G be _Graph; ::_thesis: for e, x, y being set holds
( e Joins x,y,G iff ( e DJoins x,y,G or e DJoins y,x,G ) )
let e, x, y be set ; ::_thesis: ( e Joins x,y,G iff ( e DJoins x,y,G or e DJoins y,x,G ) )
hereby  ::_thesis: ( ( e DJoins x,y,G or e DJoins y,x,G ) implies e Joins x,y,G )
assume A1: e Joins x,y,G ; ::_thesis: ( e DJoins x,y,G or e DJoins y,x,G )
then A2: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by Def13;
 e in the_Edges_of G by A1, Def13;
hence  ( e DJoins x,y,G or e DJoins y,x,G ) by A2, Def14; ::_thesis: verum
end;
assume A3: ( e DJoins x,y,G or e DJoins y,x,G ) ; ::_thesis: e Joins x,y,G
then A4: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by Def14;
 e in the_Edges_of G by A3, Def14;
hence  e Joins x,y,G by A4, Def13; ::_thesis: verum
end;

definition
let G be _Graph;
attrG is finite  means :Def17: :: GLIB_000:def 17
( the_Vertices_of G is finite & the_Edges_of G is finite );
attrG is loopless  means :Def18: :: GLIB_000:def 18
 for e being set holds
( not e in the_Edges_of G or not (the_Source_of G) . e = (the_Target_of G) . e );
attrG is trivial  means :Def19: :: GLIB_000:def 19
 card (the_Vertices_of G) = 1;
attrG is non-multi  means :Def20: :: GLIB_000:def 20
 for e1, e2, v1, v2 being set st e1 Joins v1,v2,G & e2 Joins v1,v2,G holds
e1 = e2;
attrG is non-Dmulti  means :Def21: :: GLIB_000:def 21
 for e1, e2, v1, v2 being set st e1 DJoins v1,v2,G & e2 DJoins v1,v2,G holds
e1 = e2;
end;

:: deftheorem Def17 defines finite GLIB_000:def_17_:_
 for G being _Graph holds
( G is finite iff ( the_Vertices_of G is finite & the_Edges_of G is finite ) );

:: deftheorem Def18 defines loopless GLIB_000:def_18_:_
 for G being _Graph holds
( G is loopless iff for e being set holds
( not e in the_Edges_of G or not (the_Source_of G) . e = (the_Target_of G) . e ) );

:: deftheorem Def19 defines trivial GLIB_000:def_19_:_
 for G being _Graph holds
( G is trivial iff card (the_Vertices_of G) = 1 );

:: deftheorem Def20 defines non-multi GLIB_000:def_20_:_
 for G being _Graph holds
( G is non-multi iff for e1, e2, v1, v2 being set st e1 Joins v1,v2,G & e2 Joins v1,v2,G holds
e1 = e2 );

:: deftheorem Def21 defines non-Dmulti GLIB_000:def_21_:_
 for G being _Graph holds
( G is non-Dmulti iff for e1, e2, v1, v2 being set st e1 DJoins v1,v2,G & e2 DJoins v1,v2,G holds
e1 = e2 );

definition
let G be _Graph;
attrG is simple  means :Def22: :: GLIB_000:def 22
( G is loopless & G is non-multi );
attrG is Dsimple  means :Def23: :: GLIB_000:def 23
( G is loopless & G is non-Dmulti );
end;

:: deftheorem Def22 defines simple GLIB_000:def_22_:_
 for G being _Graph holds
( G is simple iff ( G is loopless & G is non-multi ) );

:: deftheorem Def23 defines Dsimple GLIB_000:def_23_:_
 for G being _Graph holds
( G is Dsimple iff ( G is loopless & G is non-Dmulti ) );

Lm3:  for G being _Graph st the_Edges_of G = {} holds
G is simple
proof
let G be _Graph; ::_thesis: ( the_Edges_of G = {} implies G is simple )
assume A1: the_Edges_of G = {} ; ::_thesis: G is simple
then  for e being set holds
( not e in the_Edges_of G or not (the_Source_of G) . e = (the_Target_of G) . e ) ;
then A2: G is loopless by Def18;
 for e1, e2, v1, v2 being set st e1 Joins v1,v2,G & e2 Joins v1,v2,G holds
e1 = e2 by A1, Def13;
then  G is non-multi by Def20;
hence  G is simple by A2, Def22; ::_thesis: verum
end;

registration
cluster Relation-like NAT -defined Function-like finite [Graph-like] non-multi  ->  non-Dmulti for set ;
coherence
 for b1 being _Graph st b1 is non-multi holds
b1 is non-Dmulti
proof
let G be _Graph; ::_thesis: ( G is non-multi implies G is non-Dmulti )
assume A1: G is non-multi ; ::_thesis: G is non-Dmulti
now__::_thesis:_for_e1,_e2,_v1,_v2_being_set_st_e1_DJoins_v1,v2,G_&_e2_DJoins_v1,v2,G_holds_
e1_=_e2
let e1, e2, v1, v2 be set ; ::_thesis: ( e1 DJoins v1,v2,G & e2 DJoins v1,v2,G implies e1 = e2 )
assume  ( e1 DJoins v1,v2,G & e2 DJoins v1,v2,G ) ; ::_thesis: e1 = e2
then  ( e1 Joins v1,v2,G & e2 Joins v1,v2,G ) by Lm2;
hence  e1 = e2 by A1, Def20; ::_thesis: verum
end;
hence  G is non-Dmulti by Def21; ::_thesis: verum
end;
cluster Relation-like NAT -defined Function-like finite [Graph-like] simple  ->  loopless non-multi for set ;
coherence
 for b1 being _Graph st b1 is simple holds
( b1 is loopless & b1 is non-multi ) by Def22;
cluster Relation-like NAT -defined Function-like finite [Graph-like] loopless non-multi  ->  simple for set ;
coherence
 for b1 being _Graph st b1 is loopless & b1 is non-multi holds
b1 is simple by Def22;
cluster Relation-like NAT -defined Function-like finite [Graph-like] loopless non-Dmulti  ->  Dsimple for set ;
coherence
 for b1 being _Graph st b1 is loopless & b1 is non-Dmulti holds
b1 is Dsimple by Def23;
cluster Relation-like NAT -defined Function-like finite [Graph-like] Dsimple  ->  loopless non-Dmulti for set ;
coherence
 for b1 being _Graph st b1 is Dsimple holds
( b1 is loopless & b1 is non-Dmulti ) by Def23;
cluster Relation-like NAT -defined Function-like finite [Graph-like] loopless trivial  ->  finite for set ;
coherence
 for b1 being _Graph st b1 is trivial & b1 is loopless holds
b1 is finite
proof
let G be _Graph; ::_thesis: ( G is trivial & G is loopless implies G is finite )
assume that
A2: G is trivial and
A3: G is loopless ; ::_thesis: G is finite
 card (the_Vertices_of G) = 1 by A2, Def19;
then consider v being set  such that
A4: the_Vertices_of G = {v} by CARD_2:42;
now__::_thesis:_the_Edges_of_G_is_finite
percases ( the_Edges_of G is empty or not the_Edges_of G is empty ) ;
suppose the_Edges_of G is empty ; ::_thesis: the_Edges_of G is finite
hence  the_Edges_of G is finite ; ::_thesis: verum
end;
suppose not the_Edges_of G is empty ; ::_thesis: the_Edges_of G is finite
then consider e being set  such that
A5: e in the_Edges_of G by XBOOLE_0:def_1;
 (the_Target_of G) . e in the_Vertices_of G by A5, FUNCT_2:5;
then A6: (the_Target_of G) . e = v by A4, TARSKI:def_1;
 (the_Source_of G) . e in the_Vertices_of G by A5, FUNCT_2:5;
then  (the_Source_of G) . e = v by A4, TARSKI:def_1;
hence  the_Edges_of G is finite by A3, A5, A6, Def18; ::_thesis: verum
end;
end;
end;
hence  G is finite by A4, Def17; ::_thesis: verum
end;
cluster Relation-like NAT -defined Function-like finite [Graph-like] trivial non-Dmulti  ->  finite for set ;
coherence
 for b1 being _Graph st b1 is trivial & b1 is non-Dmulti holds
b1 is finite
proof
let G be _Graph; ::_thesis: ( G is trivial & G is non-Dmulti implies G is finite )
assume that
A7: G is trivial and
A8: G is non-Dmulti ; ::_thesis: G is finite
 card (the_Vertices_of G) = 1 by A7, Def19;
then consider v being set  such that
A9: the_Vertices_of G = {v} by CARD_2:42;
now__::_thesis:_the_Edges_of_G_is_finite
set e1 = choose (the_Edges_of G);
set v1 = (the_Source_of G) . (choose (the_Edges_of G));
set v2 = (the_Target_of G) . (choose (the_Edges_of G));
assume A10: not the_Edges_of G is finite ; ::_thesis: contradiction
then A11: the_Edges_of G <> {} ;
 (the_Target_of G) . (choose (the_Edges_of G)) in the_Vertices_of G by A10, FUNCT_2:5;
then A12: (the_Target_of G) . (choose (the_Edges_of G)) = v by A9, TARSKI:def_1;
 (the_Source_of G) . (choose (the_Edges_of G)) in the_Vertices_of G by A10, FUNCT_2:5;
then  (the_Source_of G) . (choose (the_Edges_of G)) = v by A9, TARSKI:def_1;
then A13: choose (the_Edges_of G) DJoins v,v,G by A11, A12, Def14;
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_{(choose_(the_Edges_of_G))}_implies_x_in_the_Edges_of_G_)_&_(_x_in_the_Edges_of_G_implies_x_in_{(choose_(the_Edges_of_G))}_)_)
let x be set ; ::_thesis: ( ( x in {(choose (the_Edges_of G))} implies x in the_Edges_of G ) & ( x in the_Edges_of G implies x in {(choose (the_Edges_of G))} ) )
set v1 = (the_Source_of G) . x;
set v2 = (the_Target_of G) . x;
hereby  ::_thesis: ( x in the_Edges_of G implies x in {(choose (the_Edges_of G))} )
assume  x in {(choose (the_Edges_of G))} ; ::_thesis: x in the_Edges_of G
then  x = choose (the_Edges_of G) by TARSKI:def_1;
hence  x in the_Edges_of G by A11; ::_thesis: verum
end;
assume A14: x in the_Edges_of G ; ::_thesis: x in {(choose (the_Edges_of G))}
then  (the_Target_of G) . x in the_Vertices_of G by FUNCT_2:5;
then A15: (the_Target_of G) . x = v by A9, TARSKI:def_1;
 (the_Source_of G) . x in the_Vertices_of G by A14, FUNCT_2:5;
then  (the_Source_of G) . x = v by A9, TARSKI:def_1;
then  x DJoins v,v,G by A14, A15, Def14;
then  x = choose (the_Edges_of G) by A8, A13, Def21;
hence  x in {(choose (the_Edges_of G))} by TARSKI:def_1; ::_thesis: verum
end;
hence  contradiction by A10, TARSKI:1; ::_thesis: verum
end;
hence  G is finite by A9, Def17; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like finite [Graph-like] trivial simple for set ;
existence
 ex b1 being _Graph st
( b1 is trivial & b1 is simple )
proof
set V = {1};
set E = {} ;
reconsider S = {} as Function of {},{1} by RELSET_1:12;
set G = createGraph ({1},{},S,S);
take  createGraph ({1},{},S,S) ; ::_thesis: ( createGraph ({1},{},S,S) is trivial & createGraph ({1},{},S,S) is simple )
 the_Vertices_of (createGraph ({1},{},S,S)) = {1} by FINSEQ_4:76;
then  card (the_Vertices_of (createGraph ({1},{},S,S))) = 1 by CARD_1:30;
hence  createGraph ({1},{},S,S) is trivial by Def19; ::_thesis: createGraph ({1},{},S,S) is simple
 the_Edges_of (createGraph ({1},{},S,S)) = {} by FINSEQ_4:76;
then  for e1, e2, v1, v2 being set st e1 Joins v1,v2, createGraph ({1},{},S,S) & e2 Joins v1,v2, createGraph ({1},{},S,S) holds
e1 = e2 by Def13;
then A1: createGraph ({1},{},S,S) is non-multi by Def20;
 for e being set holds
( not e in the_Edges_of (createGraph ({1},{},S,S)) or not (the_Source_of (createGraph ({1},{},S,S))) . e = (the_Target_of (createGraph ({1},{},S,S))) . e ) by FINSEQ_4:76;
then  createGraph ({1},{},S,S) is loopless by Def18;
hence  createGraph ({1},{},S,S) is simple by A1; ::_thesis: verum
end;
cluster Relation-like NAT -defined Function-like finite [Graph-like] finite non trivial simple for set ;
existence
 ex b1 being _Graph st
( b1 is finite & not b1 is trivial & b1 is simple )
proof
set V = {1,2};
set E = {} ;
reconsider S = {} as Function of {},{1,2} by RELSET_1:12;
set G = createGraph ({1,2},{},S,S);
take  createGraph ({1,2},{},S,S) ; ::_thesis: ( createGraph ({1,2},{},S,S) is finite & not createGraph ({1,2},{},S,S) is trivial & createGraph ({1,2},{},S,S) is simple )
A2: the_Edges_of (createGraph ({1,2},{},S,S)) = {} by FINSEQ_4:76;
A3: the_Vertices_of (createGraph ({1,2},{},S,S)) = {1,2} by FINSEQ_4:76;
hence  createGraph ({1,2},{},S,S) is finite by A2, Def17; ::_thesis: ( not createGraph ({1,2},{},S,S) is trivial & createGraph ({1,2},{},S,S) is simple )
 card (the_Vertices_of (createGraph ({1,2},{},S,S))) <> 1 by A3, CARD_2:57;
hence  not createGraph ({1,2},{},S,S) is trivial by Def19; ::_thesis: createGraph ({1,2},{},S,S) is simple
 for e being set holds
( not e in the_Edges_of (createGraph ({1,2},{},S,S)) or not (the_Source_of (createGraph ({1,2},{},S,S))) . e = (the_Target_of (createGraph ({1,2},{},S,S))) . e ) by FINSEQ_4:76;
then A4: createGraph ({1,2},{},S,S) is loopless by Def18;
 for e1, e2, v1, v2 being set st e1 Joins v1,v2, createGraph ({1,2},{},S,S) & e2 Joins v1,v2, createGraph ({1,2},{},S,S) holds
e1 = e2 by A2, Def13;
then  createGraph ({1,2},{},S,S) is non-multi by Def20;
hence  createGraph ({1,2},{},S,S) is simple by A4; ::_thesis: verum
end;
end;

registration
let G be finite _Graph;
cluster the_Vertices_of G ->  finite ;
coherence
 the_Vertices_of G is finite by Def17;
cluster the_Edges_of G ->  finite ;
coherence
 the_Edges_of G is finite by Def17;
end;

registration
let G be trivial _Graph;
cluster the_Vertices_of G ->  finite ;
coherence
 the_Vertices_of G is finite
proof
 card (the_Vertices_of G) = 1 by Def19;
hence  the_Vertices_of G is finite ; ::_thesis: verum
end;
end;

registration
let V be non empty finite set ;
let E be finite set ;
let S, T be Function of E,V;
cluster createGraph (V,E,S,T) ->  finite ;
coherence
 createGraph (V,E,S,T) is finite
proof
set G = createGraph (V,E,S,T);
 ( the_Vertices_of (createGraph (V,E,S,T)) = V & the_Edges_of (createGraph (V,E,S,T)) = E ) by FINSEQ_4:76;
hence  createGraph (V,E,S,T) is finite by Def17; ::_thesis: verum
end;
end;

registration
let V be non empty set ;
let E be empty set ;
let S, T be Function of E,V;
cluster createGraph (V,E,S,T) ->  simple ;
coherence
 createGraph (V,E,S,T) is simple
proof
set G = createGraph (V,E,S,T);
 the_Edges_of (createGraph (V,E,S,T)) = E by FINSEQ_4:76;
then  for e1, e2, v1, v2 being set st e1 Joins v1,v2, createGraph (V,E,S,T) & e2 Joins v1,v2, createGraph (V,E,S,T) holds
e1 = e2 by Def13;
then A1: createGraph (V,E,S,T) is non-multi by Def20;
 for e being set holds
( not e in the_Edges_of (createGraph (V,E,S,T)) or not (the_Source_of (createGraph (V,E,S,T))) . e = (the_Target_of (createGraph (V,E,S,T))) . e ) by FINSEQ_4:76;
then  createGraph (V,E,S,T) is loopless by Def18;
hence  createGraph (V,E,S,T) is simple by A1; ::_thesis: verum
end;
end;

registration
let v, E be set ;
let S, T be Function of E,{v};
cluster createGraph ({v},E,S,T) ->  trivial ;
coherence
 createGraph ({v},E,S,T) is trivial
proof
set G = createGraph ({v},E,S,T);
 the_Vertices_of (createGraph ({v},E,S,T)) = {v} by FINSEQ_4:76;
then  card (the_Vertices_of (createGraph ({v},E,S,T))) = 1 by CARD_1:30;
hence  createGraph ({v},E,S,T) is trivial by Def19; ::_thesis: verum
end;
end;

definition
let G be _Graph;
funcG .order()  ->  Cardinal equals :: GLIB_000:def 24
 card (the_Vertices_of G);
coherence
 card (the_Vertices_of G) is Cardinal ;
end;

:: deftheorem  defines .order() GLIB_000:def_24_:_
 for G being _Graph holds G .order() = card (the_Vertices_of G);

definition
let G be finite _Graph;
:: original: .order()
redefine funcG .order()  ->  non empty Element of NAT ;
coherence
 G .order() is non empty Element of NAT
proof
 G .order() = card (the_Vertices_of G) ;
hence  G .order() is non empty Element of NAT ; ::_thesis: verum
end;
end;

definition
let G be _Graph;
funcG .size()  ->  Cardinal equals :: GLIB_000:def 25
 card (the_Edges_of G);
coherence
 card (the_Edges_of G) is Cardinal ;
end;

:: deftheorem  defines .size() GLIB_000:def_25_:_
 for G being _Graph holds G .size() = card (the_Edges_of G);

definition
let G be finite _Graph;
:: original: .size()
redefine funcG .size()  ->  Element of NAT ;
coherence
 G .size() is Element of NAT
proof
 G .size() = card (the_Edges_of G) ;
hence  G .size() is Element of NAT ; ::_thesis: verum
end;
end;

definition
let G be _Graph;
let X be set ;
funcG .edgesInto X ->  Subset of (the_Edges_of G) means :Def26: :: GLIB_000:def 26
 for e being set holds
( e in it iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) );
existence
 ex b1 being Subset of (the_Edges_of G) st
for e being set holds
( e in b1 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) )
proof
defpred S1[ set ] means (the_Target_of G) . $1 in X;
consider IT being Subset of (the_Edges_of G) such that
A1: for e being set holds
( e in IT iff ( e in the_Edges_of G & S1[e] ) ) from SUBSET_1:sch_1();
take  IT ; ::_thesis: for e being set holds
( e in IT iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) )
thus  for e being set holds
( e in IT iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) by A1; ::_thesis: verum
end;
uniqueness
 for b1, b2 being Subset of (the_Edges_of G) st ( for e being set holds
( e in b1 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) ) & ( for e being set holds
( e in b2 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) ) holds
b1 = b2
proof
let IT1, IT2 be Subset of (the_Edges_of G); ::_thesis: ( ( for e being set holds
( e in IT1 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) ) & ( for e being set holds
( e in IT2 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) ) implies IT1 = IT2 )
assume that
A2: for e being set holds
( e in IT1 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) and
A3: for e being set holds
( e in IT2 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) ; ::_thesis: IT1 = IT2
now__::_thesis:_for_e_being_set_holds_
(_(_e_in_IT1_implies_e_in_IT2_)_&_(_e_in_IT2_implies_e_in_IT1_)_)
let e be set ; ::_thesis: ( ( e in IT1 implies e in IT2 ) & ( e in IT2 implies e in IT1 ) )
hereby  ::_thesis: ( e in IT2 implies e in IT1 )
assume A4: e in IT1 ; ::_thesis: e in IT2
then  (the_Target_of G) . e in X by A2;
hence  e in IT2 by A3, A4; ::_thesis: verum
end;
assume A5: e in IT2 ; ::_thesis: e in IT1
then  (the_Target_of G) . e in X by A3;
hence  e in IT1 by A2, A5; ::_thesis: verum
end;
hence  IT1 = IT2 by TARSKI:1; ::_thesis: verum
end;
funcG .edgesOutOf X ->  Subset of (the_Edges_of G) means :Def27: :: GLIB_000:def 27
 for e being set holds
( e in it iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) );
existence
 ex b1 being Subset of (the_Edges_of G) st
for e being set holds
( e in b1 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) )
proof
defpred S1[ set ] means (the_Source_of G) . $1 in X;
consider IT being Subset of (the_Edges_of G) such that
A6: for e being set holds
( e in IT iff ( e in the_Edges_of G & S1[e] ) ) from SUBSET_1:sch_1();
take  IT ; ::_thesis: for e being set holds
( e in IT iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) )
thus  for e being set holds
( e in IT iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) by A6; ::_thesis: verum
end;
uniqueness
 for b1, b2 being Subset of (the_Edges_of G) st ( for e being set holds
( e in b1 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) ) & ( for e being set holds
( e in b2 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) ) holds
b1 = b2
proof
let IT1, IT2 be Subset of (the_Edges_of G); ::_thesis: ( ( for e being set holds
( e in IT1 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) ) & ( for e being set holds
( e in IT2 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) ) implies IT1 = IT2 )
assume that
A7: for e being set holds
( e in IT1 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) and
A8: for e being set holds
( e in IT2 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) ; ::_thesis: IT1 = IT2
now__::_thesis:_for_e_being_set_holds_
(_(_e_in_IT1_implies_e_in_IT2_)_&_(_e_in_IT2_implies_e_in_IT1_)_)
let e be set ; ::_thesis: ( ( e in IT1 implies e in IT2 ) & ( e in IT2 implies e in IT1 ) )
hereby  ::_thesis: ( e in IT2 implies e in IT1 )
assume A9: e in IT1 ; ::_thesis: e in IT2
then  (the_Source_of G) . e in X by A7;
hence  e in IT2 by A8, A9; ::_thesis: verum
end;
assume A10: e in IT2 ; ::_thesis: e in IT1
then  (the_Source_of G) . e in X by A8;
hence  e in IT1 by A7, A10; ::_thesis: verum
end;
hence  IT1 = IT2 by TARSKI:1; ::_thesis: verum
end;
end;

:: deftheorem Def26 defines .edgesInto GLIB_000:def_26_:_
 for G being _Graph
for X being set
for b3 being Subset of (the_Edges_of G) holds
( b3 = G .edgesInto X iff for e being set holds
( e in b3 iff ( e in the_Edges_of G & (the_Target_of G) . e in X ) ) );

:: deftheorem Def27 defines .edgesOutOf GLIB_000:def_27_:_
 for G being _Graph
for X being set
for b3 being Subset of (the_Edges_of G) holds
( b3 = G .edgesOutOf X iff for e being set holds
( e in b3 iff ( e in the_Edges_of G & (the_Source_of G) . e in X ) ) );

definition
let G be _Graph;
let X be set ;
funcG .edgesInOut X ->  Subset of (the_Edges_of G) equals :: GLIB_000:def 28
(G .edgesInto X) \/ (G .edgesOutOf X);
coherence
 (G .edgesInto X) \/ (G .edgesOutOf X) is Subset of (the_Edges_of G) ;
funcG .edgesBetween X ->  Subset of (the_Edges_of G) equals :: GLIB_000:def 29
(G .edgesInto X) /\ (G .edgesOutOf X);
coherence
 (G .edgesInto X) /\ (G .edgesOutOf X) is Subset of (the_Edges_of G) ;
end;

:: deftheorem  defines .edgesInOut GLIB_000:def_28_:_
 for G being _Graph
for X being set holds G .edgesInOut X = (G .edgesInto X) \/ (G .edgesOutOf X);

:: deftheorem  defines .edgesBetween GLIB_000:def_29_:_
 for G being _Graph
for X being set holds G .edgesBetween X = (G .edgesInto X) /\ (G .edgesOutOf X);

definition
let G be _Graph;
let X, Y be set ;
funcG .edgesBetween (X,Y) ->  Subset of (the_Edges_of G) means :Def30: :: GLIB_000:def 30
 for e being set holds
( e in it iff e SJoins X,Y,G );
existence
 ex b1 being Subset of (the_Edges_of G) st
for e being set holds
( e in b1 iff e SJoins X,Y,G )
proof
defpred S1[ set ] means $1 SJoins X,Y,G;
consider IT being Subset of (the_Edges_of G) such that
A1: for e being set holds
( e in IT iff ( e in the_Edges_of G & S1[e] ) ) from SUBSET_1:sch_1();
take  IT ; ::_thesis: for e being set holds
( e in IT iff e SJoins X,Y,G )
let e be set ; ::_thesis: ( e in IT iff e SJoins X,Y,G )
thus  ( e in IT implies S1[e] ) by A1; ::_thesis: ( e SJoins X,Y,G implies e in IT )
assume A2: e SJoins X,Y,G ; ::_thesis: e in IT
then  e in the_Edges_of G by Def15;
hence  e in IT by A1, A2; ::_thesis: verum
end;
uniqueness
 for b1, b2 being Subset of (the_Edges_of G) st ( for e being set holds
( e in b1 iff e SJoins X,Y,G ) ) & ( for e being set holds
( e in b2 iff e SJoins X,Y,G ) ) holds
b1 = b2
proof
let IT1, IT2 be Subset of (the_Edges_of G); ::_thesis: ( ( for e being set holds
( e in IT1 iff e SJoins X,Y,G ) ) & ( for e being set holds
( e in IT2 iff e SJoins X,Y,G ) ) implies IT1 = IT2 )
assume that
A3: for e being set holds
( e in IT1 iff e SJoins X,Y,G ) and
A4: for e being set holds
( e in IT2 iff e SJoins X,Y,G ) ; ::_thesis: IT1 = IT2
now__::_thesis:_for_e_being_set_holds_
(_e_in_IT2_iff_e_in_IT1_)
let e be set ; ::_thesis: ( e in IT2 iff e in IT1 )
 ( e in IT1 iff e SJoins X,Y,G ) by A3;
hence  ( e in IT2 iff e in IT1 ) by A4; ::_thesis: verum
end;
hence  IT1 = IT2 by TARSKI:1; ::_thesis: verum
end;
funcG .edgesDBetween (X,Y) ->  Subset of (the_Edges_of G) means :Def31: :: GLIB_000:def 31
 for e being set holds
( e in it iff e DSJoins X,Y,G );
existence
 ex b1 being Subset of (the_Edges_of G) st
for e being set holds
( e in b1 iff e DSJoins X,Y,G )
proof
defpred S1[ set ] means $1 DSJoins X,Y,G;
consider IT being Subset of (the_Edges_of G) such that
A5: for e being set holds
( e in IT iff ( e in the_Edges_of G & S1[e] ) ) from SUBSET_1:sch_1();
take  IT ; ::_thesis: for e being set holds
( e in IT iff e DSJoins X,Y,G )
let e be set ; ::_thesis: ( e in IT iff e DSJoins X,Y,G )
thus  ( e in IT implies S1[e] ) by A5; ::_thesis: ( e DSJoins X,Y,G implies e in IT )
assume A6: e DSJoins X,Y,G ; ::_thesis: e in IT
then  e in the_Edges_of G by Def16;
hence  e in IT by A5, A6; ::_thesis: verum
end;
uniqueness
 for b1, b2 being Subset of (the_Edges_of G) st ( for e being set holds
( e in b1 iff e DSJoins X,Y,G ) ) & ( for e being set holds
( e in b2 iff e DSJoins X,Y,G ) ) holds
b1 = b2
proof
let IT1, IT2 be Subset of (the_Edges_of G); ::_thesis: ( ( for e being set holds
( e in IT1 iff e DSJoins X,Y,G ) ) & ( for e being set holds
( e in IT2 iff e DSJoins X,Y,G ) ) implies IT1 = IT2 )
assume that
A7: for e being set holds
( e in IT1 iff e DSJoins X,Y,G ) and
A8: for e being set holds
( e in IT2 iff e DSJoins X,Y,G ) ; ::_thesis: IT1 = IT2
now__::_thesis:_for_e_being_set_holds_
(_e_in_IT2_iff_e_in_IT1_)
let e be set ; ::_thesis: ( e in IT2 iff e in IT1 )
 ( e in IT1 iff e DSJoins X,Y,G ) by A7;
hence  ( e in IT2 iff e in IT1 ) by A8; ::_thesis: verum
end;
hence  IT1 = IT2 by TARSKI:1; ::_thesis: verum
end;
end;

:: deftheorem Def30 defines .edgesBetween GLIB_000:def_30_:_
 for G being _Graph
for X, Y being set
for b4 being Subset of (the_Edges_of G) holds
( b4 = G .edgesBetween (X,Y) iff for e being set holds
( e in b4 iff e SJoins X,Y,G ) );

:: deftheorem Def31 defines .edgesDBetween GLIB_000:def_31_:_
 for G being _Graph
for X, Y being set
for b4 being Subset of (the_Edges_of G) holds
( b4 = G .edgesDBetween (X,Y) iff for e being set holds
( e in b4 iff e DSJoins X,Y,G ) );

scheme :: GLIB_000:sch 1
FinGraphOrderInd{ P1[ finite _Graph] } :
 for G being finite _Graph holds P1[G]
provided
A1: for G being finite _Graph st G .order() = 1 holds
P1[G] and
A2: for k being non empty Nat st ( for Gk being finite _Graph st Gk .order() = k holds
P1[Gk] ) holds
for Gk1 being finite _Graph st Gk1 .order() = k + 1 holds
P1[Gk1]
proof
defpred S1[ Nat] means  for G being finite _Graph st G .order() = $1 holds
P1[G];
A3: for k being non empty Nat st S1[k] holds
S1[k + 1] by A2;
let G be finite _Graph; ::_thesis: P1[G]
A4: G .order() = G .order() ;
A5: S1[1] by A1;
 for k being non empty Nat holds S1[k] from NAT_1:sch_10(A5, A3);
hence  P1[G] by A4; ::_thesis: verum
end;

scheme :: GLIB_000:sch 2
FinGraphSizeInd{ P1[ finite _Graph] } :
 for G being finite _Graph holds P1[G]
provided
A1: for G being finite _Graph st G .size() = 0 holds
P1[G] and
A2: for k being Element of NAT st ( for Gk being finite _Graph st Gk .size() = k holds
P1[Gk] ) holds
for Gk1 being finite _Graph st Gk1 .size() = k + 1 holds
P1[Gk1]
proof
defpred S1[ Element of NAT ] means  for G being finite _Graph st G .size() = $1 holds
P1[G];
A3: for k being Element of NAT st S1[k] holds
S1[k + 1] by A2;
let G be finite _Graph; ::_thesis: P1[G]
A4: G .size() = G .size() ;
A5: S1[ 0 ] by A1;
 for k being Element of NAT holds S1[k] from NAT_1:sch_1(A5, A3);
hence  P1[G] by A4; ::_thesis: verum
end;

definition
let G be _Graph;
mode Subgraph of G ->  _Graph means :Def32: :: GLIB_000:def 32
( the_Vertices_of it c= the_Vertices_of G & the_Edges_of it c= the_Edges_of G & ( for e being set st e in the_Edges_of it holds
( (the_Source_of it) . e = (the_Source_of G) . e & (the_Target_of it) . e = (the_Target_of G) . e ) ) );
existence
 ex b1 being _Graph st
( the_Vertices_of b1 c= the_Vertices_of G & the_Edges_of b1 c= the_Edges_of G & ( for e being set st e in the_Edges_of b1 holds
( (the_Source_of b1) . e = (the_Source_of G) . e & (the_Target_of b1) . e = (the_Target_of G) . e ) ) )
proof
take  G ; ::_thesis: ( the_Vertices_of G c= the_Vertices_of G & the_Edges_of G c= the_Edges_of G & ( for e being set st e in the_Edges_of G holds
( (the_Source_of G) . e = (the_Source_of G) . e & (the_Target_of G) . e = (the_Target_of G) . e ) ) )
thus  ( the_Vertices_of G c= the_Vertices_of G & the_Edges_of G c= the_Edges_of G & ( for e being set st e in the_Edges_of G holds
( (the_Source_of G) . e = (the_Source_of G) . e & (the_Target_of G) . e = (the_Target_of G) . e ) ) ) ; ::_thesis: verum
end;
end;

:: deftheorem Def32 defines Subgraph GLIB_000:def_32_:_
 for G, b2 being _Graph holds
( b2 is Subgraph of G iff ( the_Vertices_of b2 c= the_Vertices_of G & the_Edges_of b2 c= the_Edges_of G & ( for e being set st e in the_Edges_of b2 holds
( (the_Source_of b2) . e = (the_Source_of G) . e & (the_Target_of b2) . e = (the_Target_of G) . e ) ) ) );

definition
let G1 be _Graph;
let G2 be Subgraph of G1;
:: original: the_Vertices_of
redefine func the_Vertices_of G2 ->  non empty Subset of (the_Vertices_of G1);
coherence
 the_Vertices_of G2 is non empty Subset of (the_Vertices_of G1) by Def32;
:: original: the_Edges_of
redefine func the_Edges_of G2 ->  Subset of (the_Edges_of G1);
coherence
 the_Edges_of G2 is Subset of (the_Edges_of G1) by Def32;
end;

registration
let G be _Graph;
cluster Relation-like NAT -defined Function-like finite [Graph-like] trivial simple for Subgraph of G;
existence
 ex b1 being Subgraph of G st
( b1 is trivial & b1 is simple )
proof
set v = the Element of the_Vertices_of G;
set V = { the Element of the_Vertices_of G};
set E = {} ;
reconsider S = {} as Function of {},{ the Element of the_Vertices_of G} by RELSET_1:12;
set IT = createGraph ({ the Element of the_Vertices_of G},{},S,S);
A1: ( the_Vertices_of (createGraph ({ the Element of the_Vertices_of G},{},S,S)) = { the Element of the_Vertices_of G} & ( for e being set st e in the_Edges_of (createGraph ({ the Element of the_Vertices_of G},{},S,S)) holds
( (the_Source_of (createGraph ({ the Element of the_Vertices_of G},{},S,S))) . e = (the_Source_of G) . e & (the_Target_of (createGraph ({ the Element of the_Vertices_of G},{},S,S))) . e = (the_Target_of G) . e ) ) ) by FINSEQ_4:76;
 the_Edges_of (createGraph ({ the Element of the_Vertices_of G},{},S,S)) = {} by FINSEQ_4:76;
then  the_Edges_of (createGraph ({ the Element of the_Vertices_of G},{},S,S)) c= the_Edges_of G by XBOOLE_1:2;
then reconsider IT = createGraph ({ the Element of the_Vertices_of G},{},S,S) as Subgraph of G by A1, Def32;
take  IT ; ::_thesis: ( IT is trivial & IT is simple )
thus  ( IT is trivial & IT is simple ) ; ::_thesis: verum
end;
end;

Lm4:  for G being _Graph holds G is Subgraph of G
proof
let G be _Graph; ::_thesis: G is Subgraph of G
 for e being set st e in the_Edges_of G holds
( (the_Source_of G) . e = (the_Source_of G) . e & (the_Target_of G) . e = (the_Target_of G) . e ) ;
hence  G is Subgraph of G by Def32; ::_thesis: verum
end;

Lm5:  for G1 being _Graph
for G2 being Subgraph of G1
for x, y, e being set st e Joins x,y,G2 holds
e Joins x,y,G1
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for x, y, e being set st e Joins x,y,G2 holds
e Joins x,y,G1
let G2 be Subgraph of G1; ::_thesis: for x, y, e being set st e Joins x,y,G2 holds
e Joins x,y,G1
let x, y, e be set ; ::_thesis: ( e Joins x,y,G2 implies e Joins x,y,G1 )
assume A1: e Joins x,y,G2 ; ::_thesis: e Joins x,y,G1
then A2: e in the_Edges_of G2 by Def13;
 ( ( (the_Source_of G2) . e = x & (the_Target_of G2) . e = y ) or ( (the_Source_of G2) . e = y & (the_Target_of G2) . e = x ) ) by A1, Def13;
then  ( ( (the_Source_of G1) . e = x & (the_Target_of G1) . e = y ) or ( (the_Source_of G1) . e = y & (the_Target_of G1) . e = x ) ) by A2, Def32;
hence  e Joins x,y,G1 by A2, Def13; ::_thesis: verum
end;

registration
let G be finite _Graph;
cluster  ->  finite for Subgraph of G;
coherence
 for b1 being Subgraph of G holds b1 is finite
proof
let G2 be Subgraph of G; ::_thesis: G2 is finite
 ( the_Vertices_of G2 is finite & the_Edges_of G2 is finite ) ;
hence  G2 is finite by Def17; ::_thesis: verum
end;
end;

registration
let G be loopless _Graph;
cluster  ->  loopless for Subgraph of G;
coherence
 for b1 being Subgraph of G holds b1 is loopless
proof
let G2 be Subgraph of G; ::_thesis: G2 is loopless
now__::_thesis:_for_e_being_set_holds_
(_not_e_in_the_Edges_of_G2_or_not_(the_Source_of_G2)_._e_=_(the_Target_of_G2)_._e_)
given e being set  such that A1: e in the_Edges_of G2 and
A2: (the_Source_of G2) . e = (the_Target_of G2) . e ; ::_thesis: contradiction
 ( (the_Source_of G2) . e = (the_Source_of G) . e & (the_Target_of G2) . e = (the_Target_of G) . e ) by A1, Def32;
hence  contradiction by A1, A2, Def18; ::_thesis: verum
end;
hence  G2 is loopless by Def18; ::_thesis: verum
end;
end;

registration
let G be trivial _Graph;
cluster  ->  trivial for Subgraph of G;
coherence
 for b1 being Subgraph of G holds b1 is trivial
proof
let G2 be Subgraph of G; ::_thesis: G2 is trivial
 card (the_Vertices_of G) = 1 by Def19;
then consider v being set  such that
A1: the_Vertices_of G = {v} by CARD_2:42;
 the_Vertices_of G2 = {v} by A1, ZFMISC_1:33;
then  card (the_Vertices_of G2) = 1 by CARD_1:30;
hence  G2 is trivial by Def19; ::_thesis: verum
end;
end;

registration
let G be non-multi _Graph;
cluster  ->  non-multi for Subgraph of G;
coherence
 for b1 being Subgraph of G holds b1 is non-multi
proof
let G2 be Subgraph of G; ::_thesis: G2 is non-multi
now__::_thesis:_for_e1,_e2,_v1,_v2_being_set_st_e1_Joins_v1,v2,G2_&_e2_Joins_v1,v2,G2_holds_
e1_=_e2
let e1, e2, v1, v2 be set ; ::_thesis: ( e1 Joins v1,v2,G2 & e2 Joins v1,v2,G2 implies e1 = e2 )
assume  ( e1 Joins v1,v2,G2 & e2 Joins v1,v2,G2 ) ; ::_thesis: e1 = e2
then  ( e1 Joins v1,v2,G & e2 Joins v1,v2,G ) by Lm5;
hence  e1 = e2 by Def20; ::_thesis: verum
end;
hence  G2 is non-multi by Def20; ::_thesis: verum
end;
end;

definition
let G1 be _Graph;
let G2 be Subgraph of G1;
attrG2 is spanning  means :Def33: :: GLIB_000:def 33
 the_Vertices_of G2 = the_Vertices_of G1;
end;

:: deftheorem Def33 defines spanning GLIB_000:def_33_:_
 for G1 being _Graph
for G2 being Subgraph of G1 holds
( G2 is spanning iff the_Vertices_of G2 = the_Vertices_of G1 );

registration
let G be _Graph;
cluster Relation-like NAT -defined Function-like finite [Graph-like] spanning for Subgraph of G;
existence
 ex b1 being Subgraph of G st b1 is spanning
proof
reconsider G9 = G as Subgraph of G by Lm4;
take  G9 ; ::_thesis: G9 is spanning
 the_Vertices_of G9 = the_Vertices_of G ;
hence  G9 is spanning by Def33; ::_thesis: verum
end;
end;

definition
let G1, G2 be _Graph;
predG1 == G2 means :Def34: :: GLIB_000:def 34
( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 );
reflexivity
 for G1 being _Graph holds
( the_Vertices_of G1 = the_Vertices_of G1 & the_Edges_of G1 = the_Edges_of G1 & the_Source_of G1 = the_Source_of G1 & the_Target_of G1 = the_Target_of G1 ) ;
symmetry
 for G1, G2 being _Graph st the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = the_Edges_of G1 & the_Source_of G2 = the_Source_of G1 & the_Target_of G2 = the_Target_of G1 ) ;
end;

:: deftheorem Def34 defines == GLIB_000:def_34_:_
 for G1, G2 being _Graph holds
( G1 == G2 iff ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) );

notation
let G1, G2 be _Graph;
antonym G1 != G2 for G1 == G2;
end;

definition
let G1, G2 be _Graph;
predG1 c= G2 means :Def35: :: GLIB_000:def 35
G1 is Subgraph of G2;
reflexivity
 for G1 being _Graph holds G1 is Subgraph of G1 by Lm4;
end;

:: deftheorem Def35 defines c= GLIB_000:def_35_:_
 for G1, G2 being _Graph holds
( G1 c= G2 iff G1 is Subgraph of G2 );

definition
let G1, G2 be _Graph;
predG1 c< G2 means :Def36: :: GLIB_000:def 36
( G1 c= G2 & G1 != G2 );
irreflexivity
 for G1 being _Graph holds
( not G1 c= G1 or not G1 != G1 ) ;
end;

:: deftheorem Def36 defines c< GLIB_000:def_36_:_
 for G1, G2 being _Graph holds
( G1 c< G2 iff ( G1 c= G2 & G1 != G2 ) );

definition
let G be _Graph;
let V, E be set ;
mode inducedSubgraph of G,V,E ->  Subgraph of G means :Def37: :: GLIB_000:def 37
( the_Vertices_of it = V & the_Edges_of it = E ) if ( V is non empty Subset of (the_Vertices_of G) & E c= G .edgesBetween V )
otherwise it == G;
existence
 ( ( V is non empty Subset of (the_Vertices_of G) & E c= G .edgesBetween V implies ex b1 being Subgraph of G st
( the_Vertices_of b1 = V & the_Edges_of b1 = E ) ) & ( ( not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) implies ex b1 being Subgraph of G st b1 == G ) )
proof
hereby  ::_thesis: ( ( not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) implies ex b1 being Subgraph of G st b1 == G )
assume that
A1: V is non empty Subset of (the_Vertices_of G) and
A2: E c= G .edgesBetween V ; ::_thesis: ex IT being Subgraph of G st
( the_Vertices_of IT = V & the_Edges_of IT = E )
reconsider E9 = E as Subset of (the_Edges_of G) by A2, XBOOLE_1:1;
set S = (the_Source_of G) | E9;
set T = (the_Target_of G) | E9;
reconsider V9 = V as non empty Subset of (the_Vertices_of G) by A1;
 dom (the_Target_of G) = the_Edges_of G by FUNCT_2:def_1;
then A3: dom ((the_Target_of G) | E9) = E9 by RELAT_1:62;
now__::_thesis:_for_e_being_set_st_e_in_E9_holds_
((the_Target_of_G)_|_E9)_._e_in_V
let e be set ; ::_thesis: ( e in E9 implies ((the_Target_of G) | E9) . e in V )
assume A4: e in E9 ; ::_thesis: ((the_Target_of G) | E9) . e in V
then  e in G .edgesInto V by A2, XBOOLE_0:def_4;
then  (the_Target_of G) . e in V by Def26;
hence  ((the_Target_of G) | E9) . e in V by A4, FUNCT_1:49; ::_thesis: verum
end;
then reconsider T = (the_Target_of G) | E9 as Function of E9,V9 by A3, FUNCT_2:3;
 dom (the_Source_of G) = the_Edges_of G by FUNCT_2:def_1;
then A5: dom ((the_Source_of G) | E9) = E9 by RELAT_1:62;
now__::_thesis:_for_e_being_set_st_e_in_E9_holds_
((the_Source_of_G)_|_E9)_._e_in_V
let e be set ; ::_thesis: ( e in E9 implies ((the_Source_of G) | E9) . e in V )
assume A6: e in E9 ; ::_thesis: ((the_Source_of G) | E9) . e in V
then  e in G .edgesOutOf V by A2, XBOOLE_0:def_4;
then  (the_Source_of G) . e in V by Def27;
hence  ((the_Source_of G) | E9) . e in V by A6, FUNCT_1:49; ::_thesis: verum
end;
then reconsider S = (the_Source_of G) | E9 as Function of E9,V9 by A5, FUNCT_2:3;
set IT = createGraph (V9,E9,S,T);
A7: the_Edges_of (createGraph (V9,E9,S,T)) = E by FINSEQ_4:76;
 ( the_Source_of (createGraph (V9,E9,S,T)) = S & the_Target_of (createGraph (V9,E9,S,T)) = T ) by FINSEQ_4:76;
then  ( the_Vertices_of (createGraph (V9,E9,S,T)) = V & ( for e being set st e in the_Edges_of (createGraph (V9,E9,S,T)) holds
( (the_Source_of (createGraph (V9,E9,S,T))) . e = (the_Source_of G) . e & (the_Target_of (createGraph (V9,E9,S,T))) . e = (the_Target_of G) . e ) ) ) by A7, FINSEQ_4:76, FUNCT_1:49;
then reconsider IT = createGraph (V9,E9,S,T) as Subgraph of G by A7, Def32;
take IT = IT; ::_thesis: ( the_Vertices_of IT = V & the_Edges_of IT = E )
thus  ( the_Vertices_of IT = V & the_Edges_of IT = E ) by FINSEQ_4:76; ::_thesis: verum
end;
 G is Subgraph of G by Lm4;
hence  ( ( not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) implies ex b1 being Subgraph of G st b1 == G ) ; ::_thesis: verum
end;
consistency
 for b1 being Subgraph of G holds verum ;
end;

:: deftheorem Def37 defines inducedSubgraph GLIB_000:def_37_:_
 for G being _Graph
for V, E being set
for b4 being Subgraph of G holds
( ( V is non empty Subset of (the_Vertices_of G) & E c= G .edgesBetween V implies ( b4 is inducedSubgraph of G,V,E iff ( the_Vertices_of b4 = V & the_Edges_of b4 = E ) ) ) & ( ( not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) implies ( b4 is inducedSubgraph of G,V,E iff b4 == G ) ) );

definition
let G be _Graph;
let V be set ;
mode inducedSubgraph of G,V is inducedSubgraph of G,V,G .edgesBetween V;
end;

registration
let G be _Graph;
let V be non empty finite Subset of (the_Vertices_of G);
let E be finite Subset of (G .edgesBetween V);
cluster  ->  finite for inducedSubgraph of G,V,E;
coherence
 for b1 being inducedSubgraph of G,V,E holds b1 is finite
proof
let IT be inducedSubgraph of G,V,E; ::_thesis: IT is finite
 ( the_Vertices_of IT = V & the_Edges_of IT = E ) by Def37;
hence  IT is finite by Def17; ::_thesis: verum
end;
end;

registration
let G be _Graph;
let v be Element of the_Vertices_of G;
let E be Subset of (G .edgesBetween {v});
cluster  ->  trivial for inducedSubgraph of G,{v},E;
coherence
 for b1 being inducedSubgraph of G,{v},E holds b1 is trivial
proof
let IT be inducedSubgraph of G,{v},E; ::_thesis: IT is trivial
 the_Vertices_of IT = {v} by Def37;
then  card (the_Vertices_of IT) = 1 by CARD_1:30;
hence  IT is trivial by Def19; ::_thesis: verum
end;
end;

registration
let G be _Graph;
let v be Element of the_Vertices_of G;
cluster  ->  finite trivial for inducedSubgraph of G,{v}, {} ;
coherence
 for b1 being inducedSubgraph of G,{v}, {} holds
( b1 is finite & b1 is trivial )
proof
reconsider E = {} as finite Subset of (G .edgesBetween {v}) by XBOOLE_1:2;
let IT be inducedSubgraph of G,{v}, {} ; ::_thesis: ( IT is finite & IT is trivial )
 IT is inducedSubgraph of G,{v},E ;
hence  ( IT is finite & IT is trivial ) ; ::_thesis: verum
end;
end;

registration
let G be _Graph;
let V be non empty Subset of (the_Vertices_of G);
cluster  ->  simple for inducedSubgraph of G,V, {} ;
coherence
 for b1 being inducedSubgraph of G,V, {} holds b1 is simple
proof
let IT be inducedSubgraph of G,V, {} ; ::_thesis: IT is simple
reconsider E = {} as Subset of (G .edgesBetween V) by XBOOLE_1:2;
 IT is inducedSubgraph of G,V,E ;
then  the_Edges_of IT = {} by Def37;
hence  IT is simple by Lm3; ::_thesis: verum
end;
end;

Lm6:  for G being _Graph
for e, X being set holds
( ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) iff e in G .edgesBetween X )
proof
let G be _Graph; ::_thesis: for e, X being set holds
( ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) iff e in G .edgesBetween X )
let e, X be set ; ::_thesis: ( ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) iff e in G .edgesBetween X )
hereby  ::_thesis: ( e in G .edgesBetween X implies ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) )
assume  ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) ; ::_thesis: e in G .edgesBetween X
then  ( e in G .edgesInto X & e in G .edgesOutOf X ) by Def26, Def27;
hence  e in G .edgesBetween X by XBOOLE_0:def_4; ::_thesis: verum
end;
assume  e in G .edgesBetween X ; ::_thesis: ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X )
then  ( e in G .edgesInto X & e in G .edgesOutOf X ) by XBOOLE_0:def_4;
hence  ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) by Def26, Def27; ::_thesis: verum
end;

Lm7:  for G being _Graph holds the_Edges_of G = G .edgesBetween (the_Vertices_of G)
proof
let G be _Graph; ::_thesis: the_Edges_of G = G .edgesBetween (the_Vertices_of G)
set EG = the_Edges_of G;
set SG = the_Source_of G;
set TG = the_Target_of G;
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_the_Edges_of_G_implies_x_in_G_.edgesBetween_(the_Vertices_of_G)_)_&_(_x_in_G_.edgesBetween_(the_Vertices_of_G)_implies_x_in_the_Edges_of_G_)_)
let x be set ; ::_thesis: ( ( x in the_Edges_of G implies x in G .edgesBetween (the_Vertices_of G) ) & ( x in G .edgesBetween (the_Vertices_of G) implies x in the_Edges_of G ) )
hereby  ::_thesis: ( x in G .edgesBetween (the_Vertices_of G) implies x in the_Edges_of G )
assume A1: x in the_Edges_of G ; ::_thesis: x in G .edgesBetween (the_Vertices_of G)
then  ( (the_Source_of G) . x in the_Vertices_of G & (the_Target_of G) . x in the_Vertices_of G ) by FUNCT_2:5;
hence  x in G .edgesBetween (the_Vertices_of G) by A1, Lm6; ::_thesis: verum
end;
assume  x in G .edgesBetween (the_Vertices_of G) ; ::_thesis: x in the_Edges_of G
hence  x in the_Edges_of G ; ::_thesis: verum
end;
hence  the_Edges_of G = G .edgesBetween (the_Vertices_of G) by TARSKI:1; ::_thesis: verum
end;

registration
let G be _Graph;
let E be Subset of (the_Edges_of G);
cluster  ->  spanning for inducedSubgraph of G, the_Vertices_of G,E;
coherence
 for b1 being inducedSubgraph of G, the_Vertices_of G,E holds b1 is spanning
proof
let G1 be inducedSubgraph of G, the_Vertices_of G,E; ::_thesis: G1 is spanning
 ( G .edgesBetween (the_Vertices_of G) = the_Edges_of G & the_Vertices_of G c= the_Vertices_of G ) by Lm7;
then  the_Vertices_of G1 = the_Vertices_of G by Def37;
hence  G1 is spanning by Def33; ::_thesis: verum
end;
end;

registration
let G be _Graph;
cluster  ->  spanning for inducedSubgraph of G, the_Vertices_of G, {} ;
coherence
 for b1 being inducedSubgraph of G, the_Vertices_of G, {} holds b1 is spanning
proof
let G1 be inducedSubgraph of G, the_Vertices_of G, {} ; ::_thesis: G1 is spanning
 ( the_Vertices_of G c= the_Vertices_of G & {} c= G .edgesBetween (the_Vertices_of G) ) by XBOOLE_1:2;
then  the_Vertices_of G1 = the_Vertices_of G by Def37;
hence  G1 is spanning by Def33; ::_thesis: verum
end;
end;

definition
let G be _Graph;
let v be set ;
mode removeVertex of G,v is inducedSubgraph of G,((the_Vertices_of G) \ {v});
end;

definition
let G be _Graph;
let V be set ;
mode removeVertices of G,V is inducedSubgraph of G,((the_Vertices_of G) \ V);
end;

definition
let G be _Graph;
let e be set ;
mode removeEdge of G,e is inducedSubgraph of G, the_Vertices_of G,(the_Edges_of G) \ {e};
end;

definition
let G be _Graph;
let E be set ;
mode removeEdges of G,E is inducedSubgraph of G, the_Vertices_of G,(the_Edges_of G) \ E;
end;

registration
let G be _Graph;
let e be set ;
cluster  ->  spanning for inducedSubgraph of G, the_Vertices_of G,(the_Edges_of G) \ {e};
coherence
 for b1 being removeEdge of G,e holds b1 is spanning ;
end;

registration
let G be _Graph;
let E be set ;
cluster  ->  spanning for inducedSubgraph of G, the_Vertices_of G,(the_Edges_of G) \ E;
coherence
 for b1 being removeEdges of G,E holds b1 is spanning ;
end;

definition
let G be _Graph;
mode Vertex of G is Element of the_Vertices_of G;
end;

definition
let G be _Graph;
let v be Vertex of G;
funcv .edgesIn()  ->  Subset of (the_Edges_of G) equals :: GLIB_000:def 38
G .edgesInto {v};
coherence
 G .edgesInto {v} is Subset of (the_Edges_of G) ;
funcv .edgesOut()  ->  Subset of (the_Edges_of G) equals :: GLIB_000:def 39
G .edgesOutOf {v};
coherence
 G .edgesOutOf {v} is Subset of (the_Edges_of G) ;
funcv .edgesInOut()  ->  Subset of (the_Edges_of G) equals :: GLIB_000:def 40
G .edgesInOut {v};
coherence
 G .edgesInOut {v} is Subset of (the_Edges_of G) ;
end;

:: deftheorem  defines .edgesIn() GLIB_000:def_38_:_
 for G being _Graph
for v being Vertex of G holds v .edgesIn() = G .edgesInto {v};

:: deftheorem  defines .edgesOut() GLIB_000:def_39_:_
 for G being _Graph
for v being Vertex of G holds v .edgesOut() = G .edgesOutOf {v};

:: deftheorem  defines .edgesInOut() GLIB_000:def_40_:_
 for G being _Graph
for v being Vertex of G holds v .edgesInOut() = G .edgesInOut {v};

Lm8:  for G being _Graph
for v being Vertex of G
for e being set holds
( e in v .edgesIn() iff ( e in the_Edges_of G & (the_Target_of G) . e = v ) )
proof
let G be _Graph; ::_thesis: for v being Vertex of G
for e being set holds
( e in v .edgesIn() iff ( e in the_Edges_of G & (the_Target_of G) . e = v ) )
let v be Vertex of G; ::_thesis: for e being set holds
( e in v .edgesIn() iff ( e in the_Edges_of G & (the_Target_of G) . e = v ) )
let e be set ; ::_thesis: ( e in v .edgesIn() iff ( e in the_Edges_of G & (the_Target_of G) . e = v ) )
hereby  ::_thesis: ( e in the_Edges_of G & (the_Target_of G) . e = v implies e in v .edgesIn() )
assume A1: e in v .edgesIn() ; ::_thesis: ( e in the_Edges_of G & (the_Target_of G) . e = v )
then  (the_Target_of G) . e in {v} by Def26;
hence  ( e in the_Edges_of G & (the_Target_of G) . e = v ) by A1, TARSKI:def_1; ::_thesis: verum
end;
assume that
A2: e in the_Edges_of G and
A3: (the_Target_of G) . e = v ; ::_thesis: e in v .edgesIn()
 (the_Target_of G) . e in {v} by A3, TARSKI:def_1;
hence  e in v .edgesIn() by A2, Def26; ::_thesis: verum
end;

Lm9:  for G being _Graph
for v being Vertex of G
for e being set holds
( e in v .edgesOut() iff ( e in the_Edges_of G & (the_Source_of G) . e = v ) )
proof
let G be _Graph; ::_thesis: for v being Vertex of G
for e being set holds
( e in v .edgesOut() iff ( e in the_Edges_of G & (the_Source_of G) . e = v ) )
let v be Vertex of G; ::_thesis: for e being set holds
( e in v .edgesOut() iff ( e in the_Edges_of G & (the_Source_of G) . e = v ) )
let e be set ; ::_thesis: ( e in v .edgesOut() iff ( e in the_Edges_of G & (the_Source_of G) . e = v ) )
hereby  ::_thesis: ( e in the_Edges_of G & (the_Source_of G) . e = v implies e in v .edgesOut() )
assume A1: e in v .edgesOut() ; ::_thesis: ( e in the_Edges_of G & (the_Source_of G) . e = v )
then  (the_Source_of G) . e in {v} by Def27;
hence  ( e in the_Edges_of G & (the_Source_of G) . e = v ) by A1, TARSKI:def_1; ::_thesis: verum
end;
assume that
A2: e in the_Edges_of G and
A3: (the_Source_of G) . e = v ; ::_thesis: e in v .edgesOut()
 (the_Source_of G) . e in {v} by A3, TARSKI:def_1;
hence  e in v .edgesOut() by A2, Def27; ::_thesis: verum
end;

definition
let G be _Graph;
let v be Vertex of G;
let e be set ;
funcv .adj e ->  Vertex of G equals :Def41: :: GLIB_000:def 41
(the_Source_of G) . e if ( e in the_Edges_of G & (the_Target_of G) . e = v )
(the_Target_of G) . e if ( e in the_Edges_of G & (the_Source_of G) . e = v & not (the_Target_of G) . e = v )
otherwise v;
coherence
 ( ( e in the_Edges_of G & (the_Target_of G) . e = v implies (the_Source_of G) . e is Vertex of G ) & ( e in the_Edges_of G & (the_Source_of G) . e = v & not (the_Target_of G) . e = v implies (the_Target_of G) . e is Vertex of G ) & ( ( not e in the_Edges_of G or not (the_Target_of G) . e = v ) & ( not e in the_Edges_of G or not (the_Source_of G) . e = v or (the_Target_of G) . e = v ) implies v is Vertex of G ) ) by FUNCT_2:5;
consistency
 for b1 being Vertex of G st e in the_Edges_of G & (the_Target_of G) . e = v & e in the_Edges_of G & (the_Source_of G) . e = v & not (the_Target_of G) . e = v holds
( b1 = (the_Source_of G) . e iff b1 = (the_Target_of G) . e ) ;
end;

:: deftheorem Def41 defines .adj GLIB_000:def_41_:_
 for G being _Graph
for v being Vertex of G
for e being set holds
( ( e in the_Edges_of G & (the_Target_of G) . e = v implies v .adj e = (the_Source_of G) . e ) & ( e in the_Edges_of G & (the_Source_of G) . e = v & not (the_Target_of G) . e = v implies v .adj e = (the_Target_of G) . e ) & ( ( not e in the_Edges_of G or not (the_Target_of G) . e = v ) & ( not e in the_Edges_of G or not (the_Source_of G) . e = v or (the_Target_of G) . e = v ) implies v .adj e = v ) );

definition
let G be _Graph;
let v be Vertex of G;
funcv .inDegree()  ->  Cardinal equals :: GLIB_000:def 42
 card (v .edgesIn());
coherence
 card (v .edgesIn()) is Cardinal ;
funcv .outDegree()  ->  Cardinal equals :: GLIB_000:def 43
 card (v .edgesOut());
coherence
 card (v .edgesOut()) is Cardinal ;
end;

:: deftheorem  defines .inDegree() GLIB_000:def_42_:_
 for G being _Graph
for v being Vertex of G holds v .inDegree() = card (v .edgesIn());

:: deftheorem  defines .outDegree() GLIB_000:def_43_:_
 for G being _Graph
for v being Vertex of G holds v .outDegree() = card (v .edgesOut());

definition
let G be finite _Graph;
let v be Vertex of G;
:: original: .inDegree()
redefine funcv .inDegree()  ->  Element of NAT ;
coherence
 v .inDegree() is Element of NAT
proof
 v .inDegree() = card (v .edgesIn()) ;
hence  v .inDegree() is Element of NAT ; ::_thesis: verum
end;
:: original: .outDegree()
redefine funcv .outDegree()  ->  Element of NAT ;
coherence
 v .outDegree() is Element of NAT
proof
 v .outDegree() = card (v .edgesOut()) ;
hence  v .outDegree() is Element of NAT ; ::_thesis: verum
end;
end;

definition
let G be _Graph;
let v be Vertex of G;
funcv .degree()  ->  Cardinal equals :: GLIB_000:def 44
(v .inDegree()) +` (v .outDegree());
coherence
 (v .inDegree()) +` (v .outDegree()) is Cardinal ;
end;

:: deftheorem  defines .degree() GLIB_000:def_44_:_
 for G being _Graph
for v being Vertex of G holds v .degree() = (v .inDegree()) +` (v .outDegree());

definition
let G be finite _Graph;
let v be Vertex of G;
:: original: .degree()
redefine funcv .degree()  ->  Element of NAT  equals :: GLIB_000:def 45
(v .inDegree()) + (v .outDegree());
correctness
coherence
v .degree() is Element of NAT ;
compatibility
for b1 being Element of NAT holds
( b1 = v .degree() iff b1 = (v .inDegree()) + (v .outDegree()) );
proof
v .degree() = card ((v .inDegree()) +^ (v .outDegree())) by CARD_2:def_1
.= card ((v .inDegree()) + (v .outDegree())) by CARD_2:36
.= (v .inDegree()) + (v .outDegree()) by CARD_1:def_2 ;
hence  ( v .degree() is Element of NAT & ( for b1 being Element of NAT holds
( b1 = v .degree() iff b1 = (v .inDegree()) + (v .outDegree()) ) ) ) ; ::_thesis: verum
end;
end;

:: deftheorem  defines .degree() GLIB_000:def_45_:_
 for G being finite _Graph
for v being Vertex of G holds v .degree() = (v .inDegree()) + (v .outDegree());

definition
let G be _Graph;
let v be Vertex of G;
funcv .inNeighbors()  ->  Subset of (the_Vertices_of G) equals :: GLIB_000:def 46
(the_Source_of G) .: (v .edgesIn());
coherence
 (the_Source_of G) .: (v .edgesIn()) is Subset of (the_Vertices_of G) ;
funcv .outNeighbors()  ->  Subset of (the_Vertices_of G) equals :: GLIB_000:def 47
(the_Target_of G) .: (v .edgesOut());
coherence
 (the_Target_of G) .: (v .edgesOut()) is Subset of (the_Vertices_of G) ;
end;

:: deftheorem  defines .inNeighbors() GLIB_000:def_46_:_
 for G being _Graph
for v being Vertex of G holds v .inNeighbors() = (the_Source_of G) .: (v .edgesIn());

:: deftheorem  defines .outNeighbors() GLIB_000:def_47_:_
 for G being _Graph
for v being Vertex of G holds v .outNeighbors() = (the_Target_of G) .: (v .edgesOut());

definition
let G be _Graph;
let v be Vertex of G;
funcv .allNeighbors()  ->  Subset of (the_Vertices_of G) equals :: GLIB_000:def 48
(v .inNeighbors()) \/ (v .outNeighbors());
coherence
 (v .inNeighbors()) \/ (v .outNeighbors()) is Subset of (the_Vertices_of G) ;
end;

:: deftheorem  defines .allNeighbors() GLIB_000:def_48_:_
 for G being _Graph
for v being Vertex of G holds v .allNeighbors() = (v .inNeighbors()) \/ (v .outNeighbors());

definition
let G be _Graph;
let v be Vertex of G;
attrv is isolated  means :Def49: :: GLIB_000:def 49
v .edgesInOut() = {} ;
end;

:: deftheorem Def49 defines isolated GLIB_000:def_49_:_
 for G being _Graph
for v being Vertex of G holds
( v is isolated iff v .edgesInOut() = {} );

definition
let G be finite _Graph;
let v be Vertex of G;
redefine attr v is isolated  means :: GLIB_000:def 50
v .degree() = 0 ;
compatibility
 ( v is isolated iff v .degree() = 0 )
proof
hereby  ::_thesis: ( v .degree() = 0 implies v is isolated )
assume  v is isolated ; ::_thesis: v .degree() = 0
then A1: v .edgesInOut() = {} by Def49;
then  v .inDegree() = 0 by CARD_1:27, XBOOLE_1:15;
hence  v .degree() = 0 by A1, CARD_1:27, XBOOLE_1:15; ::_thesis: verum
end;
assume A2: v .degree() = 0 ; ::_thesis: v is isolated
then  v .edgesIn() = {} ;
then  v .edgesInOut() = {} by A2;
hence  v is isolated by Def49; ::_thesis: verum
end;
end;

:: deftheorem  defines isolated GLIB_000:def_50_:_
 for G being finite _Graph
for v being Vertex of G holds
( v is isolated iff v .degree() = 0 );

definition
let G be _Graph;
let v be Vertex of G;
attrv is endvertex  means :Def51: :: GLIB_000:def 51
 ex e being set st
( v .edgesInOut() = {e} & not e Joins v,v,G );
end;

:: deftheorem Def51 defines endvertex GLIB_000:def_51_:_
 for G being _Graph
for v being Vertex of G holds
( v is endvertex iff ex e being set st
( v .edgesInOut() = {e} & not e Joins v,v,G ) );

definition
let G be finite _Graph;
let v be Vertex of G;
redefine attr v is endvertex  means :: GLIB_000:def 52
v .degree() = 1;
compatibility
 ( v is endvertex iff v .degree() = 1 )
proof
hereby  ::_thesis: ( v .degree() = 1 implies v is endvertex )
assume  v is endvertex ; ::_thesis: v .degree() = 1
then consider e being set  such that
A1: v .edgesInOut() = {e} and
A2: not e Joins v,v,G by Def51;
now__::_thesis:_v_.degree()_=_1
percases ( ( v .edgesIn() = {e} & v .edgesOut() = {e} ) or ( v .edgesIn() = {} & v .edgesOut() = {e} ) or ( v .edgesIn() = {e} & v .edgesOut() = {} ) ) by A1, ZFMISC_1:37;
supposeA3: ( v .edgesIn() = {e} & v .edgesOut() = {e} ) ; ::_thesis: v .degree() = 1
then  e in v .edgesOut() by TARSKI:def_1;
then A4: (the_Source_of G) . e = v by Lm9;
A5: e in v .edgesIn() by A3, TARSKI:def_1;
then  (the_Target_of G) . e = v by Lm8;
hence  v .degree() = 1 by A2, A5, A4, Def13; ::_thesis: verum
end;
suppose ( v .edgesIn() = {} & v .edgesOut() = {e} ) ; ::_thesis: v .degree() = 1
hence  v .degree() = 1 by CARD_1:27, CARD_1:30; ::_thesis: verum
end;
suppose ( v .edgesIn() = {e} & v .edgesOut() = {} ) ; ::_thesis: v .degree() = 1
hence  v .degree() = 1 by CARD_1:27, CARD_1:30; ::_thesis: verum
end;
end;
end;
hence  v .degree() = 1 ; ::_thesis: verum
end;
assume A6: v .degree() = 1 ; ::_thesis: v is endvertex
now__::_thesis:_v_is_endvertex
percases ( card (v .edgesIn()) = 0 or card (v .edgesIn()) <> 0 ) ;
supposeA7: card (v .edgesIn()) = 0 ; ::_thesis: v is endvertex
then consider e being set  such that
A8: v .edgesOut() = {e} by A6, CARD_2:42;
A9: v .edgesIn() = {} by A7;
A10: now__::_thesis:_not_e_Joins_v,v,G
assume  e Joins v,v,G ; ::_thesis: contradiction
then  ( e in the_Edges_of G & (the_Target_of G) . e = v ) by Def13;
hence  contradiction by A9, Lm8; ::_thesis: verum
end;
 v .edgesInOut() = {e} by A9, A8;
hence  v is endvertex by A10, Def51; ::_thesis: verum
end;
suppose card (v .edgesIn()) <> 0 ; ::_thesis: v is endvertex
then  0 < card (v .edgesIn()) by NAT_1:3;
then A11: 0 + 1 <= card (v .edgesIn()) by NAT_1:13;
 card (v .edgesIn()) <= 1 by A6, NAT_1:11;
then A12: card (v .edgesIn()) = 1 by A11, XXREAL_0:1;
then consider e being set  such that
A13: v .edgesIn() = {e} by CARD_2:42;
A14: v .edgesOut() = {} by A6, A12;
A15: now__::_thesis:_not_e_Joins_v,v,G
assume  e Joins v,v,G ; ::_thesis: contradiction
then  ( e in the_Edges_of G & (the_Source_of G) . e = v ) by Def13;
hence  contradiction by A14, Lm9; ::_thesis: verum
end;
 v .edgesInOut() = {e} by A13, A14;
hence  v is endvertex by A15, Def51; ::_thesis: verum
end;
end;
end;
hence  v is endvertex ; ::_thesis: verum
end;
end;

:: deftheorem  defines endvertex GLIB_000:def_52_:_
 for G being finite _Graph
for v being Vertex of G holds
( v is endvertex iff v .degree() = 1 );

definition
let F be ManySortedSet of NAT ;
attrF is Graph-yielding  means :Def53: :: GLIB_000:def 53
 for n being Nat holds F . n is _Graph;
attrF is halting  means :Def54: :: GLIB_000:def 54
 ex n being Nat st F . n = F . (n + 1);
end;

:: deftheorem Def53 defines Graph-yielding GLIB_000:def_53_:_
 for F being ManySortedSet of NAT holds
( F is Graph-yielding iff for n being Nat holds F . n is _Graph );

:: deftheorem Def54 defines halting GLIB_000:def_54_:_
 for F being ManySortedSet of NAT holds
( F is halting iff ex n being Nat st F . n = F . (n + 1) );

definition
let F be ManySortedSet of NAT ;
funcF .Lifespan()  ->  Element of NAT  means :: GLIB_000:def 55
( F . it = F . (it + 1) & ( for n being Nat st F . n = F . (n + 1) holds
it <= n ) ) if F is halting
otherwise it = 0 ;
existence
 ( ( F is halting implies ex b1 being Element of NAT st
( F . b1 = F . (b1 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
b1 <= n ) ) ) & ( not F is halting implies ex b1 being Element of NAT st b1 = 0 ) )
proof
defpred S1[ Nat] means F . $1 = F . ($1 + 1);
hereby  ::_thesis: ( not F is halting implies ex b1 being Element of NAT st b1 = 0 )
assume  F is halting ; ::_thesis: ex IT being Element of NAT st
( S1[IT] & ( for n being Nat st S1[n] holds
IT <= n ) )
then A1: ex n being Nat st S1[n] by Def54;
 ex IT being Nat st
( S1[IT] & ( for n being Nat st S1[n] holds
IT <= n ) ) from NAT_1:sch_5(A1);
then consider IT being Nat such that
A2: ( S1[IT] & ( for n being Nat st S1[n] holds
IT <= n ) ) ;
 IT in NAT by ORDINAL1:def_12;
hence  ex IT being Element of NAT st
( S1[IT] & ( for n being Nat st S1[n] holds
IT <= n ) ) by A2; ::_thesis: verum
end;
thus  ( not F is halting implies ex b1 being Element of NAT st b1 = 0 ) ; ::_thesis: verum
end;
uniqueness
 for b1, b2 being Element of NAT holds
( ( F is halting & F . b1 = F . (b1 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
b1 <= n ) & F . b2 = F . (b2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
b2 <= n ) implies b1 = b2 ) & ( not F is halting & b1 = 0 & b2 = 0 implies b1 = b2 ) )
proof
let IT1, IT2 be Element of NAT ; ::_thesis: ( ( F is halting & F . IT1 = F . (IT1 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT1 <= n ) & F . IT2 = F . (IT2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT2 <= n ) implies IT1 = IT2 ) & ( not F is halting & IT1 = 0 & IT2 = 0 implies IT1 = IT2 ) )
hereby  ::_thesis: ( not F is halting & IT1 = 0 & IT2 = 0 implies IT1 = IT2 )
assume  F is halting ; ::_thesis: ( F . IT1 = F . (IT1 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT1 <= n ) & F . IT2 = F . (IT2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT2 <= n ) implies IT1 = IT2 )
assume A3: ( F . IT1 = F . (IT1 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT1 <= n ) ) ; ::_thesis: ( F . IT2 = F . (IT2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT2 <= n ) implies IT1 = IT2 )
assume  ( F . IT2 = F . (IT2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
IT2 <= n ) ) ; ::_thesis: IT1 = IT2
then  ( IT1 <= IT2 & IT2 <= IT1 ) by A3;
hence  IT1 = IT2 by XXREAL_0:1; ::_thesis: verum
end;
thus  ( not F is halting & IT1 = 0 & IT2 = 0 implies IT1 = IT2 ) ; ::_thesis: verum
end;
consistency
 for b1 being Element of NAT holds verum ;
end;

:: deftheorem  defines .Lifespan() GLIB_000:def_55_:_
 for F being ManySortedSet of NAT
for b2 being Element of NAT holds
( ( F is halting implies ( b2 = F .Lifespan() iff ( F . b2 = F . (b2 + 1) & ( for n being Nat st F . n = F . (n + 1) holds
b2 <= n ) ) ) ) & ( not F is halting implies ( b2 = F .Lifespan() iff b2 = 0 ) ) );

definition
let F be ManySortedSet of NAT ;
funcF .Result()  ->  set  equals :: GLIB_000:def 56
F . (F .Lifespan());
coherence
 F . (F .Lifespan()) is set ;
end;

:: deftheorem  defines .Result() GLIB_000:def_56_:_
 for F being ManySortedSet of NAT holds F .Result() = F . (F .Lifespan());

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding for set ;
existence
 ex b1 being ManySortedSet of NAT st b1 is Graph-yielding
proof
set G = the _Graph;
set F = NAT --> the _Graph;
A1: dom (NAT --> the _Graph) = NAT by FUNCOP_1:13;
reconsider F = NAT --> the _Graph as ManySortedSet of NAT ;
take  F ; ::_thesis: F is Graph-yielding
let x be Nat; :: according to GLIB_000:def_53 ::_thesis: F . x is _Graph
 x in NAT by ORDINAL1:def_12;
then  F . x in rng F by A1, FUNCT_1:3;
then  F . x in { the _Graph} by FUNCOP_1:8;
hence  F . x is _Graph by TARSKI:def_1; ::_thesis: verum
end;
end;

definition
mode GraphSeq is Graph-yielding ManySortedSet of NAT ;
end;

registration
let GSq be GraphSeq;
let x be Nat;
clusterGSq . x ->  Relation-like Function-like ;
coherence
 ( GSq . x is Function-like & GSq . x is Relation-like ) by Def53;
end;

registration
let GSq be GraphSeq;
let x be Nat;
clusterGSq . x ->  NAT -defined finite ;
coherence
 ( GSq . x is NAT -defined & GSq . x is finite ) by Def53;
end;

registration
let GSq be GraphSeq;
let x be Nat;
clusterGSq . x ->  [Graph-like] ;
coherence
 GSq . x is [Graph-like] by Def53;
end;

definition
let GSq be GraphSeq;
attrGSq is finite  means :Def57: :: GLIB_000:def 57
 for x being Nat holds GSq . x is finite ;
attrGSq is loopless  means :Def58: :: GLIB_000:def 58
 for x being Nat holds GSq . x is loopless ;
attrGSq is trivial  means :Def59: :: GLIB_000:def 59
 for x being Nat holds GSq . x is trivial ;
attrGSq is non-trivial  means :Def60: :: GLIB_000:def 60
 for x being Nat holds not GSq . x is trivial ;
attrGSq is non-multi  means :Def61: :: GLIB_000:def 61
 for x being Nat holds GSq . x is non-multi ;
attrGSq is non-Dmulti  means :Def62: :: GLIB_000:def 62
 for x being Nat holds GSq . x is non-Dmulti ;
attrGSq is simple  means :Def63: :: GLIB_000:def 63
 for x being Nat holds GSq . x is simple ;
attrGSq is Dsimple  means :Def64: :: GLIB_000:def 64
 for x being Nat holds GSq . x is Dsimple ;
end;

:: deftheorem Def57 defines finite GLIB_000:def_57_:_
 for GSq being GraphSeq holds
( GSq is finite iff for x being Nat holds GSq . x is finite );

:: deftheorem Def58 defines loopless GLIB_000:def_58_:_
 for GSq being GraphSeq holds
( GSq is loopless iff for x being Nat holds GSq . x is loopless );

:: deftheorem Def59 defines trivial GLIB_000:def_59_:_
 for GSq being GraphSeq holds
( GSq is trivial iff for x being Nat holds GSq . x is trivial );

:: deftheorem Def60 defines non-trivial GLIB_000:def_60_:_
 for GSq being GraphSeq holds
( GSq is non-trivial iff for x being Nat holds not GSq . x is trivial );

:: deftheorem Def61 defines non-multi GLIB_000:def_61_:_
 for GSq being GraphSeq holds
( GSq is non-multi iff for x being Nat holds GSq . x is non-multi );

:: deftheorem Def62 defines non-Dmulti GLIB_000:def_62_:_
 for GSq being GraphSeq holds
( GSq is non-Dmulti iff for x being Nat holds GSq . x is non-Dmulti );

:: deftheorem Def63 defines simple GLIB_000:def_63_:_
 for GSq being GraphSeq holds
( GSq is simple iff for x being Nat holds GSq . x is simple );

:: deftheorem Def64 defines Dsimple GLIB_000:def_64_:_
 for GSq being GraphSeq holds
( GSq is Dsimple iff for x being Nat holds GSq . x is Dsimple );

definition
let GSq be GraphSeq;
redefine attr GSq is halting  means :: GLIB_000:def 65
 ex n being Nat st GSq . n = GSq . (n + 1);
compatibility
 ( GSq is halting iff ex n being Nat st GSq . n = GSq . (n + 1) ) by Def54;
end;

:: deftheorem  defines halting GLIB_000:def_65_:_
 for GSq being GraphSeq holds
( GSq is halting iff ex n being Nat st GSq . n = GSq . (n + 1) );

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding halting finite loopless trivial non-multi non-Dmulti simple Dsimple for set ;
existence
 ex b1 being GraphSeq st
( b1 is halting & b1 is finite & b1 is loopless & b1 is trivial & b1 is non-multi & b1 is non-Dmulti & b1 is simple & b1 is Dsimple )
proof
set G = the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph;
set F = NAT --> the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph;
A1: dom (NAT --> the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph) = NAT by FUNCOP_1:13;
reconsider F = NAT --> the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph as ManySortedSet of NAT ;
now__::_thesis:_for_x_being_Nat_holds_F_._x_is__Graph
let x be Nat; ::_thesis: F . x is _Graph
 x in NAT by ORDINAL1:def_12;
then  F . x in rng F by A1, FUNCT_1:3;
then  F . x in { the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
hence  F . x is _Graph by TARSKI:def_1; ::_thesis: verum
end;
then reconsider F = F as GraphSeq by Def53;
 F . (1 + 1) in rng F by A1, FUNCT_1:3;
then  F . (1 + 1) in { the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
then A2: F . (1 + 1) = the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph by TARSKI:def_1;
take  F ; ::_thesis: ( F is halting & F is finite & F is loopless & F is trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple )
 F . 1 in rng F by A1, FUNCT_1:3;
then  F . 1 in { the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
then  F . 1 = the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph by TARSKI:def_1;
hence  F is halting by A2, Def54; ::_thesis: ( F is finite & F is loopless & F is trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple )
now__::_thesis:_for_x_being_Nat_holds_
(_F_._x_is_finite_&_F_._x_is_loopless_&_F_._x_is_trivial_&_F_._x_is_non-multi_&_F_._x_is_non-Dmulti_&_F_._x_is_simple_&_F_._x_is_Dsimple_)
let x be Nat; ::_thesis: ( F . x is finite & F . x is loopless & F . x is trivial & F . x is non-multi & F . x is non-Dmulti & F . x is simple & F . x is Dsimple )
 x in NAT by ORDINAL1:def_12;
then  F . x in rng F by A1, FUNCT_1:3;
then  F . x in { the finite loopless trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
hence  ( F . x is finite & F . x is loopless & F . x is trivial & F . x is non-multi & F . x is non-Dmulti & F . x is simple & F . x is Dsimple ) by TARSKI:def_1; ::_thesis: verum
end;
hence  ( F is finite & F is loopless & F is trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple ) by Def57, Def58, Def59, Def61, Def62, Def63, Def64; ::_thesis: verum
end;
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding halting finite loopless non-trivial non-multi non-Dmulti simple Dsimple for set ;
existence
 ex b1 being GraphSeq st
( b1 is halting & b1 is finite & b1 is loopless & b1 is non-trivial & b1 is non-multi & b1 is non-Dmulti & b1 is simple & b1 is Dsimple )
proof
set G = the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph;
set F = NAT --> the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph;
A3: dom (NAT --> the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph) = NAT by FUNCOP_1:13;
reconsider F = NAT --> the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph as ManySortedSet of NAT ;
now__::_thesis:_for_x_being_Nat_holds_F_._x_is__Graph
let x be Nat; ::_thesis: F . x is _Graph
 x in NAT by ORDINAL1:def_12;
then  F . x in rng F by A3, FUNCT_1:3;
then  F . x in { the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
hence  F . x is _Graph by TARSKI:def_1; ::_thesis: verum
end;
then reconsider F = F as GraphSeq by Def53;
 F . (1 + 1) in rng F by A3, FUNCT_1:3;
then  F . (1 + 1) in { the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
then A4: F . (1 + 1) = the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph by TARSKI:def_1;
take  F ; ::_thesis: ( F is halting & F is finite & F is loopless & F is non-trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple )
 F . 1 in rng F by A3, FUNCT_1:3;
then  F . 1 in { the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
then  F . 1 = the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph by TARSKI:def_1;
hence  F is halting by A4, Def54; ::_thesis: ( F is finite & F is loopless & F is non-trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple )
now__::_thesis:_for_x_being_Nat_holds_
(_F_._x_is_finite_&_F_._x_is_loopless_&_not_F_._x_is_trivial_&_F_._x_is_non-multi_&_F_._x_is_non-Dmulti_&_F_._x_is_simple_&_F_._x_is_Dsimple_)
let x be Nat; ::_thesis: ( F . x is finite & F . x is loopless & not F . x is trivial & F . x is non-multi & F . x is non-Dmulti & F . x is simple & F . x is Dsimple )
 x in NAT by ORDINAL1:def_12;
then  F . x in rng F by A3, FUNCT_1:3;
then  F . x in { the finite loopless non trivial non-multi non-Dmulti simple Dsimple _Graph} by FUNCOP_1:8;
hence  ( F . x is finite & F . x is loopless & not F . x is trivial & F . x is non-multi & F . x is non-Dmulti & F . x is simple & F . x is Dsimple ) by TARSKI:def_1; ::_thesis: verum
end;
hence  ( F is finite & F is loopless & F is non-trivial & F is non-multi & F is non-Dmulti & F is simple & F is Dsimple ) by Def57, Def58, Def60, Def61, Def62, Def63, Def64; ::_thesis: verum
end;
end;

registration
let GSq be finite GraphSeq;
let x be Nat;
clusterGSq . x ->  finite ;
coherence
 GSq . x is finite by Def57;
end;

registration
let GSq be loopless GraphSeq;
let x be Nat;
clusterGSq . x ->  loopless for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is loopless by Def58;
end;

registration
let GSq be trivial GraphSeq;
let x be Nat;
clusterGSq . x ->  trivial for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is trivial by Def59;
end;

registration
let GSq be non-trivial GraphSeq;
let x be Nat;
clusterGSq . x ->  non trivial for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
not b1 is trivial by Def60;
end;

registration
let GSq be non-multi GraphSeq;
let x be Nat;
clusterGSq . x ->  non-multi for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is non-multi by Def61;
end;

registration
let GSq be non-Dmulti GraphSeq;
let x be Nat;
clusterGSq . x ->  non-Dmulti for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is non-Dmulti by Def62;
end;

registration
let GSq be simple GraphSeq;
let x be Nat;
clusterGSq . x ->  simple for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is simple by Def63;
end;

registration
let GSq be Dsimple GraphSeq;
let x be Nat;
clusterGSq . x ->  Dsimple for _Graph;
coherence
 for b1 being _Graph st b1 = GSq . x holds
b1 is Dsimple by Def64;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding non-multi  ->  non-Dmulti for set ;
coherence
 for b1 being GraphSeq st b1 is non-multi holds
b1 is non-Dmulti
proof
let GS be GraphSeq; ::_thesis: ( GS is non-multi implies GS is non-Dmulti )
assume  GS is non-multi ; ::_thesis: GS is non-Dmulti
then reconsider GS9 = GS as non-multi GraphSeq ;
 for x being Nat holds GS9 . x is non-Dmulti ;
hence  GS is non-Dmulti by Def62; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding simple  ->  loopless non-multi for set ;
coherence
 for b1 being GraphSeq st b1 is simple holds
( b1 is loopless & b1 is non-multi )
proof
let GS be GraphSeq; ::_thesis: ( GS is simple implies ( GS is loopless & GS is non-multi ) )
assume  GS is simple ; ::_thesis: ( GS is loopless & GS is non-multi )
then reconsider GS9 = GS as simple GraphSeq ;
 for x being Nat holds GS9 . x is loopless ;
hence  GS is loopless by Def58; ::_thesis: GS is non-multi
 for x being Nat holds GS9 . x is non-multi ;
hence  GS is non-multi by Def61; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding loopless non-multi  ->  simple for set ;
coherence
 for b1 being GraphSeq st b1 is loopless & b1 is non-multi holds
b1 is simple
proof
let GS be GraphSeq; ::_thesis: ( GS is loopless & GS is non-multi implies GS is simple )
assume  ( GS is loopless & GS is non-multi ) ; ::_thesis: GS is simple
then reconsider GS9 = GS as loopless non-multi GraphSeq ;
 for x being Nat holds GS9 . x is simple ;
hence  GS is simple by Def63; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding loopless non-Dmulti  ->  Dsimple for set ;
coherence
 for b1 being GraphSeq st b1 is loopless & b1 is non-Dmulti holds
b1 is Dsimple
proof
let GS be GraphSeq; ::_thesis: ( GS is loopless & GS is non-Dmulti implies GS is Dsimple )
assume  ( GS is loopless & GS is non-Dmulti ) ; ::_thesis: GS is Dsimple
then reconsider GS9 = GS as loopless non-Dmulti GraphSeq ;
 for x being Nat holds GS9 . x is Dsimple ;
hence  GS is Dsimple by Def64; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding Dsimple  ->  loopless non-Dmulti for set ;
coherence
 for b1 being GraphSeq st b1 is Dsimple holds
( b1 is loopless & b1 is non-Dmulti )
proof
let GS be GraphSeq; ::_thesis: ( GS is Dsimple implies ( GS is loopless & GS is non-Dmulti ) )
assume  GS is Dsimple ; ::_thesis: ( GS is loopless & GS is non-Dmulti )
then reconsider GS9 = GS as Dsimple GraphSeq ;
 for x being Nat holds GS9 . x is loopless ;
hence  GS is loopless by Def58; ::_thesis: GS is non-Dmulti
 for x being Nat holds GS9 . x is non-Dmulti ;
hence  GS is non-Dmulti by Def62; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding loopless trivial  ->  finite for set ;
coherence
 for b1 being GraphSeq st b1 is trivial & b1 is loopless holds
b1 is finite
proof
let GS be GraphSeq; ::_thesis: ( GS is trivial & GS is loopless implies GS is finite )
assume  ( GS is trivial & GS is loopless ) ; ::_thesis: GS is finite
then reconsider GS9 = GS as loopless trivial GraphSeq ;
 for x being Nat holds GS9 . x is finite ;
hence  GS is finite by Def57; ::_thesis: verum
end;
end;

registration
cluster Relation-like NAT -defined Function-like V17( NAT ) Graph-yielding trivial non-Dmulti  ->  finite for set ;
coherence
 for b1 being GraphSeq st b1 is trivial & b1 is non-Dmulti holds
b1 is finite
proof
let GS be GraphSeq; ::_thesis: ( GS is trivial & GS is non-Dmulti implies GS is finite )
assume  ( GS is trivial & GS is non-Dmulti ) ; ::_thesis: GS is finite
then reconsider GS9 = GS as trivial non-Dmulti GraphSeq ;
 for x being Nat holds GS9 . x is finite ;
hence  GS is finite by Def57; ::_thesis: verum
end;
end;

begin


theorem :: GLIB_000:1
( VertexSelector = 1 & EdgeSelector = 2 & SourceSelector = 3 & TargetSelector = 4 ) ;

theorem :: GLIB_000:2
for G being _Graph holds _GraphSelectors c= dom G
proof
let G be _Graph; ::_thesis: _GraphSelectors c= dom G
now__::_thesis:_for_x_being_set_st_x_in__GraphSelectors_holds_
x_in_dom_G
let x be set ; ::_thesis: ( x in _GraphSelectors implies x in dom G )
assume  x in _GraphSelectors ; ::_thesis: x in dom G
then  ( x = VertexSelector or x = EdgeSelector or x = SourceSelector or x = TargetSelector ) by ENUMSET1:def_2;
hence  x in dom G by Def10; ::_thesis: verum
end;
hence  _GraphSelectors c= dom G by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:3
for GS being GraphStruct holds
( the_Vertices_of GS = GS . VertexSelector & the_Edges_of GS = GS . EdgeSelector & the_Source_of GS = GS . SourceSelector & the_Target_of GS = GS . TargetSelector ) ;

theorem :: GLIB_000:4
for G being _Graph holds
( dom (the_Source_of G) = the_Edges_of G & dom (the_Target_of G) = the_Edges_of G & rng (the_Source_of G) c= the_Vertices_of G & rng (the_Target_of G) c= the_Vertices_of G ) by FUNCT_2:def_1;

theorem :: GLIB_000:5
for GS being GraphStruct holds
( GS is [Graph-like] iff ( _GraphSelectors c= dom GS & not the_Vertices_of GS is empty & the_Source_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) & the_Target_of GS is Function of (the_Edges_of GS),(the_Vertices_of GS) ) ) by Lm1;

theorem :: GLIB_000:6
for V being non empty set
for E being set
for S, T being Function of E,V holds
( the_Vertices_of (createGraph (V,E,S,T)) = V & the_Edges_of (createGraph (V,E,S,T)) = E & the_Source_of (createGraph (V,E,S,T)) = S & the_Target_of (createGraph (V,E,S,T)) = T ) by FINSEQ_4:76;

theorem Th7: :: GLIB_000:7
for GS being GraphStruct
for x being set
for n being Nat holds dom (GS .set (n,x)) = (dom GS) \/ {n}
proof
let GS be GraphStruct; ::_thesis: for x being set
for n being Nat holds dom (GS .set (n,x)) = (dom GS) \/ {n}
let x be set ; ::_thesis: for n being Nat holds dom (GS .set (n,x)) = (dom GS) \/ {n}
let n be Nat; ::_thesis: dom (GS .set (n,x)) = (dom GS) \/ {n}
set G2 = GS .set (n,x);
thus  dom (GS .set (n,x)) = (dom GS) \/ (dom (n .--> x)) by FUNCT_4:def_1
.= (dom GS) \/ {n} by FUNCOP_1:13 ; ::_thesis: verum
end;

theorem Th8: :: GLIB_000:8
for GS being GraphStruct
for x being set
for n being Nat holds (GS .set (n,x)) . n = x
proof
let GS be GraphStruct; ::_thesis: for x being set
for n being Nat holds (GS .set (n,x)) . n = x
let x be set ; ::_thesis: for n being Nat holds (GS .set (n,x)) . n = x
let n be Nat; ::_thesis: (GS .set (n,x)) . n = x
set G2 = GS .set (n,x);
 dom (n .--> x) = {n} by FUNCOP_1:13;
then  n in dom (n .--> x) by TARSKI:def_1;
hence (GS .set (n,x)) . n = (n .--> x) . n by FUNCT_4:13
.= x by FUNCOP_1:72 ;
::_thesis: verum
end;

theorem Th9: :: GLIB_000:9
for GS being GraphStruct
for x being set
for n1, n2 being Nat st n1 <> n2 holds
GS . n2 = (GS .set (n1,x)) . n2
proof
let GS be GraphStruct; ::_thesis: for x being set
for n1, n2 being Nat st n1 <> n2 holds
GS . n2 = (GS .set (n1,x)) . n2
let x be set ; ::_thesis: for n1, n2 being Nat st n1 <> n2 holds
GS . n2 = (GS .set (n1,x)) . n2
let n1, n2 be Nat; ::_thesis: ( n1 <> n2 implies GS . n2 = (GS .set (n1,x)) . n2 )
assume  n1 <> n2 ; ::_thesis: GS . n2 = (GS .set (n1,x)) . n2
then  not n2 in dom (n1 .--> x) by TARSKI:def_1;
hence  GS . n2 = (GS .set (n1,x)) . n2 by FUNCT_4:11; ::_thesis: verum
end;

theorem :: GLIB_000:10
for G being _Graph
for x being set
for n being Nat st not n in _GraphSelectors holds
( the_Vertices_of G = the_Vertices_of (G .set (n,x)) & the_Edges_of G = the_Edges_of (G .set (n,x)) & the_Source_of G = the_Source_of (G .set (n,x)) & the_Target_of G = the_Target_of (G .set (n,x)) & G .set (n,x) is _Graph )
proof
let G be _Graph; ::_thesis: for x being set
for n being Nat st not n in _GraphSelectors holds
( the_Vertices_of G = the_Vertices_of (G .set (n,x)) & the_Edges_of G = the_Edges_of (G .set (n,x)) & the_Source_of G = the_Source_of (G .set (n,x)) & the_Target_of G = the_Target_of (G .set (n,x)) & G .set (n,x) is _Graph )
let x be set ; ::_thesis: for n being Nat st not n in _GraphSelectors holds
( the_Vertices_of G = the_Vertices_of (G .set (n,x)) & the_Edges_of G = the_Edges_of (G .set (n,x)) & the_Source_of G = the_Source_of (G .set (n,x)) & the_Target_of G = the_Target_of (G .set (n,x)) & G .set (n,x) is _Graph )
let n be Nat; ::_thesis: ( not n in _GraphSelectors implies ( the_Vertices_of G = the_Vertices_of (G .set (n,x)) & the_Edges_of G = the_Edges_of (G .set (n,x)) & the_Source_of G = the_Source_of (G .set (n,x)) & the_Target_of G = the_Target_of (G .set (n,x)) & G .set (n,x) is _Graph ) )
set G2 = G .set (n,x);
A1: dom G c= dom (G .set (n,x)) by FUNCT_4:10;
assume A2: not n in _GraphSelectors ; ::_thesis: ( the_Vertices_of G = the_Vertices_of (G .set (n,x)) & the_Edges_of G = the_Edges_of (G .set (n,x)) & the_Source_of G = the_Source_of (G .set (n,x)) & the_Target_of G = the_Target_of (G .set (n,x)) & G .set (n,x) is _Graph )
then  EdgeSelector <> n by ENUMSET1:def_2;
then A3: not EdgeSelector in dom (n .--> x) by TARSKI:def_1;
 TargetSelector <> n by A2, ENUMSET1:def_2;
then A4: not TargetSelector in dom (n .--> x) by TARSKI:def_1;
 SourceSelector <> n by A2, ENUMSET1:def_2;
then A5: not SourceSelector in dom (n .--> x) by TARSKI:def_1;
 VertexSelector <> n by A2, ENUMSET1:def_2;
then  not VertexSelector in dom (n .--> x) by TARSKI:def_1;
hence A6: ( the_Vertices_of (G .set (n,x)) = the_Vertices_of G & the_Edges_of (G .set (n,x)) = the_Edges_of G & the_Source_of (G .set (n,x)) = the_Source_of G & the_Target_of (G .set (n,x)) = the_Target_of G ) by A3, A5, A4, FUNCT_4:11; ::_thesis: G .set (n,x) is _Graph
A7: ( SourceSelector in dom G & TargetSelector in dom G ) by Def10;
 ( VertexSelector in dom G & EdgeSelector in dom G ) by Def10;
hence  G .set (n,x) is _Graph by A7, A1, A6, Def10; ::_thesis: verum
end;

theorem :: GLIB_000:11
for GS being GraphStruct
for x being set holds
( the_Vertices_of (GS .set (VertexSelector,x)) = x & the_Edges_of (GS .set (EdgeSelector,x)) = x & the_Source_of (GS .set (SourceSelector,x)) = x & the_Target_of (GS .set (TargetSelector,x)) = x ) by Th8;

theorem :: GLIB_000:12
for GS being GraphStruct
for x, y being set
for n1, n2 being Nat st n1 <> n2 holds
( n1 in dom ((GS .set (n1,x)) .set (n2,y)) & n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
proof
let GS be GraphStruct; ::_thesis: for x, y being set
for n1, n2 being Nat st n1 <> n2 holds
( n1 in dom ((GS .set (n1,x)) .set (n2,y)) & n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
let x, y be set ; ::_thesis: for n1, n2 being Nat st n1 <> n2 holds
( n1 in dom ((GS .set (n1,x)) .set (n2,y)) & n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
let n1, n2 be Nat; ::_thesis: ( n1 <> n2 implies ( n1 in dom ((GS .set (n1,x)) .set (n2,y)) & n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y ) )
assume A1: n1 <> n2 ; ::_thesis: ( n1 in dom ((GS .set (n1,x)) .set (n2,y)) & n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
set G2 = GS .set (n1,x);
set G3 = (GS .set (n1,x)) .set (n2,y);
A2: dom ((GS .set (n1,x)) .set (n2,y)) = (dom (GS .set (n1,x))) \/ {n2} by Th7;
 ( dom (GS .set (n1,x)) = (dom GS) \/ {n1} & n1 in {n1} ) by Th7, TARSKI:def_1;
then  n1 in dom (GS .set (n1,x)) by XBOOLE_0:def_3;
hence  n1 in dom ((GS .set (n1,x)) .set (n2,y)) by A2, XBOOLE_0:def_3; ::_thesis: ( n2 in dom ((GS .set (n1,x)) .set (n2,y)) & ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
 n2 in {n2} by TARSKI:def_1;
hence  n2 in dom ((GS .set (n1,x)) .set (n2,y)) by A2, XBOOLE_0:def_3; ::_thesis: ( ((GS .set (n1,x)) .set (n2,y)) . n1 = x & ((GS .set (n1,x)) .set (n2,y)) . n2 = y )
thus ((GS .set (n1,x)) .set (n2,y)) . n1 = (GS .set (n1,x)) . n1 by A1, Th9
.= x by Th8 ; ::_thesis: ((GS .set (n1,x)) .set (n2,y)) . n2 = y
thus  ((GS .set (n1,x)) .set (n2,y)) . n2 = y by Th8; ::_thesis: verum
end;

theorem :: GLIB_000:13
for G being _Graph
for e, x, y being set st e Joins x,y,G holds
( x in the_Vertices_of G & y in the_Vertices_of G )
proof
let G be _Graph; ::_thesis: for e, x, y being set st e Joins x,y,G holds
( x in the_Vertices_of G & y in the_Vertices_of G )
let e, x, y be set ; ::_thesis: ( e Joins x,y,G implies ( x in the_Vertices_of G & y in the_Vertices_of G ) )
assume A1: e Joins x,y,G ; ::_thesis: ( x in the_Vertices_of G & y in the_Vertices_of G )
then A2: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by Def13;
 e in the_Edges_of G by A1, Def13;
hence  ( x in the_Vertices_of G & y in the_Vertices_of G ) by A2, FUNCT_2:5; ::_thesis: verum
end;

theorem :: GLIB_000:14
for G being _Graph
for e, x, y being set st e Joins x,y,G holds
e Joins y,x,G
proof
let G be _Graph; ::_thesis: for e, x, y being set st e Joins x,y,G holds
e Joins y,x,G
let e, x, y be set ; ::_thesis: ( e Joins x,y,G implies e Joins y,x,G )
assume A1: e Joins x,y,G ; ::_thesis: e Joins y,x,G
then A2: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by Def13;
 e in the_Edges_of G by A1, Def13;
hence  e Joins y,x,G by A2, Def13; ::_thesis: verum
end;

theorem :: GLIB_000:15
for G being _Graph
for e, x1, y1, x2, y2 being set st e Joins x1,y1,G & e Joins x2,y2,G & not ( x1 = x2 & y1 = y2 ) holds
( x1 = y2 & y1 = x2 )
proof
let G be _Graph; ::_thesis: for e, x1, y1, x2, y2 being set st e Joins x1,y1,G & e Joins x2,y2,G & not ( x1 = x2 & y1 = y2 ) holds
( x1 = y2 & y1 = x2 )
let e, x1, y1, x2, y2 be set ; ::_thesis: ( e Joins x1,y1,G & e Joins x2,y2,G & not ( x1 = x2 & y1 = y2 ) implies ( x1 = y2 & y1 = x2 ) )
assume that
A1: e Joins x1,y1,G and
A2: e Joins x2,y2,G ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
set S = (the_Source_of G) . e;
set T = (the_Target_of G) . e;
now__::_thesis:_(_(_x1_=_x2_&_y1_=_y2_)_or_(_x1_=_y2_&_y1_=_x2_)_)
percases ( ( (the_Source_of G) . e = x1 & (the_Target_of G) . e = y1 ) or ( (the_Source_of G) . e = y1 & (the_Target_of G) . e = x1 ) ) by A1, Def13;
supposeA3: ( (the_Source_of G) . e = x1 & (the_Target_of G) . e = y1 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
now__::_thesis:_(_(_x1_=_x2_&_y1_=_y2_)_or_(_x1_=_y2_&_y1_=_x2_)_)
percases ( ( (the_Source_of G) . e = x2 & (the_Target_of G) . e = y2 ) or ( (the_Source_of G) . e = y2 & (the_Target_of G) . e = x2 ) ) by A2, Def13;
suppose ( (the_Source_of G) . e = x2 & (the_Target_of G) . e = y2 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) by A3; ::_thesis: verum
end;
suppose ( (the_Source_of G) . e = y2 & (the_Target_of G) . e = x2 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) by A3; ::_thesis: verum
end;
end;
end;
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) ; ::_thesis: verum
end;
supposeA4: ( (the_Source_of G) . e = y1 & (the_Target_of G) . e = x1 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
now__::_thesis:_(_(_x1_=_x2_&_y1_=_y2_)_or_(_x1_=_y2_&_y1_=_x2_)_)
percases ( ( (the_Source_of G) . e = x2 & (the_Target_of G) . e = y2 ) or ( (the_Source_of G) . e = y2 & (the_Target_of G) . e = x2 ) ) by A2, Def13;
suppose ( (the_Source_of G) . e = x2 & (the_Target_of G) . e = y2 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) by A4; ::_thesis: verum
end;
suppose ( (the_Source_of G) . e = y2 & (the_Target_of G) . e = x2 ) ; ::_thesis: ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) )
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) by A4; ::_thesis: verum
end;
end;
end;
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) ; ::_thesis: verum
end;
end;
end;
hence  ( ( x1 = x2 & y1 = y2 ) or ( x1 = y2 & y1 = x2 ) ) ; ::_thesis: verum
end;

theorem :: GLIB_000:16
for G being _Graph
for e, x, y being set holds
( e Joins x,y,G iff ( e DJoins x,y,G or e DJoins y,x,G ) ) by Lm2;

theorem :: GLIB_000:17
for G being _Graph
for e, x, y, X, Y being set st e Joins x,y,G & ( ( x in X & y in Y ) or ( x in Y & y in X ) ) holds
e SJoins X,Y,G
proof
let G be _Graph; ::_thesis: for e, x, y, X, Y being set st e Joins x,y,G & ( ( x in X & y in Y ) or ( x in Y & y in X ) ) holds
e SJoins X,Y,G
let e, x, y, X, Y be set ; ::_thesis: ( e Joins x,y,G & ( ( x in X & y in Y ) or ( x in Y & y in X ) ) implies e SJoins X,Y,G )
assume that
A1: e Joins x,y,G and
A2: ( ( x in X & y in Y ) or ( x in Y & y in X ) ) ; ::_thesis: e SJoins X,Y,G
A3: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by A1, Def13;
 e in the_Edges_of G by A1, Def13;
hence  e SJoins X,Y,G by A2, A3, Def15; ::_thesis: verum
end;

theorem :: GLIB_000:18
for G being _Graph holds
( G is loopless iff for v, e being set holds not e Joins v,v,G )
proof
let G be _Graph; ::_thesis: ( G is loopless iff for v, e being set holds not e Joins v,v,G )
hereby  ::_thesis: ( ( for v, e being set holds not e Joins v,v,G ) implies G is loopless )
assume A1: G is loopless ; ::_thesis: for v, e being set holds not e Joins v,v,G
let v be set ; ::_thesis: for e being set holds not e Joins v,v,G
now__::_thesis:_for_e_being_set_holds_not_e_Joins_v,v,G
given e being set  such that A2: e Joins v,v,G ; ::_thesis: contradiction
A3: (the_Target_of G) . e = v by A2, Def13;
 ( e in the_Edges_of G & (the_Source_of G) . e = v ) by A2, Def13;
hence  contradiction by A1, A3, Def18; ::_thesis: verum
end;
hence  for e being set holds not e Joins v,v,G ; ::_thesis: verum
end;
assume A4: for v, e being set holds not e Joins v,v,G ; ::_thesis: G is loopless
now__::_thesis:_for_e_being_set_holds_
(_not_e_in_the_Edges_of_G_or_not_(the_Source_of_G)_._e_=_(the_Target_of_G)_._e_)
given e being set  such that A5: ( e in the_Edges_of G & (the_Source_of G) . e = (the_Target_of G) . e ) ; ::_thesis: contradiction
set v = (the_Source_of G) . e;
 e Joins (the_Source_of G) . e,(the_Source_of G) . e,G by A5, Def13;
hence  contradiction by A4; ::_thesis: verum
end;
hence  G is loopless by Def18; ::_thesis: verum
end;

theorem :: GLIB_000:19
for G being finite loopless _Graph
for v being Vertex of G holds v .degree() = card (v .edgesInOut())
proof
let G be finite loopless _Graph; ::_thesis: for v being Vertex of G holds v .degree() = card (v .edgesInOut())
let v be Vertex of G; ::_thesis: v .degree() = card (v .edgesInOut())
set In = v .edgesIn() ;
set Out = v .edgesOut() ;
now__::_thesis:_for_e_being_set_holds_not_e_in_(v_.edgesIn())_/\_(v_.edgesOut())
given e being set  such that A1: e in (v .edgesIn()) /\ (v .edgesOut()) ; ::_thesis: contradiction
 e in v .edgesOut() by A1, XBOOLE_0:def_4;
then A2: (the_Source_of G) . e = v by Lm9;
 e in v .edgesIn() by A1, XBOOLE_0:def_4;
then  (the_Target_of G) . e = v by Lm8;
hence  contradiction by A1, A2, Def18; ::_thesis: verum
end;
then  (v .edgesIn()) /\ (v .edgesOut()) = {} by XBOOLE_0:def_1;
then  v .edgesIn() misses v .edgesOut() by XBOOLE_0:def_7;
hence  v .degree() = card (v .edgesInOut()) by CARD_2:40; ::_thesis: verum
end;

theorem :: GLIB_000:20
for G being non trivial _Graph
for v being Vertex of G holds not (the_Vertices_of G) \ {v} is empty
proof
let G be non trivial _Graph; ::_thesis: for v being Vertex of G holds not (the_Vertices_of G) \ {v} is empty
let v be Vertex of G; ::_thesis: not (the_Vertices_of G) \ {v} is empty
set VG = the_Vertices_of G;
now__::_thesis:_not_(the_Vertices_of_G)_\_{v}_=_{}
assume  (the_Vertices_of G) \ {v} = {} ; ::_thesis: contradiction
then  the_Vertices_of G c= {v} by XBOOLE_1:37;
then  the_Vertices_of G = {v} by ZFMISC_1:33;
then  card (the_Vertices_of G) = 1 by CARD_1:30;
hence  contradiction by Def19; ::_thesis: verum
end;
hence  not (the_Vertices_of G) \ {v} is empty ; ::_thesis: verum
end;

theorem :: GLIB_000:21
for G being non trivial _Graph ex v1, v2 being Vertex of G st v1 <> v2
proof
let G be non trivial _Graph; ::_thesis: ex v1, v2 being Vertex of G st v1 <> v2
set VG = the_Vertices_of G;
take v1 = choose (the_Vertices_of G); ::_thesis: ex v2 being Vertex of G st v1 <> v2
set VG2 = (the_Vertices_of G) \ {v1};
now__::_thesis:_not_(the_Vertices_of_G)_\_{v1}_=_{}
assume A1: (the_Vertices_of G) \ {v1} = {} ; ::_thesis: contradiction
card (((the_Vertices_of G) \ {v1}) \/ {v1}) = (card ((the_Vertices_of G) \ {v1})) +` (card {v1}) by CARD_2:35, XBOOLE_1:79
.= 0 +` 1 by A1, CARD_1:27, CARD_1:30
.= card (0 +^ 1) by CARD_2:def_1
.= card (0 + 1) by CARD_2:36
.= 1 by CARD_1:def_2 ;
then  card (the_Vertices_of G) = 1 by XBOOLE_1:45;
hence  contradiction by Def19; ::_thesis: verum
end;
then reconsider VG2 = (the_Vertices_of G) \ {v1} as non empty set ;
set v2 = choose VG2;
A2: not choose VG2 in {v1} by XBOOLE_0:def_5;
reconsider v2 = choose VG2 as Vertex of G by XBOOLE_0:def_5;
take  v2 ; ::_thesis: v1 <> v2
thus  v1 <> v2 by A2, TARSKI:def_1; ::_thesis: verum
end;

theorem Th22: :: GLIB_000:22
for G being trivial _Graph ex v being Vertex of G st the_Vertices_of G = {v}
proof
let G be trivial _Graph; ::_thesis: ex v being Vertex of G st the_Vertices_of G = {v}
 card (the_Vertices_of G) = 1 by Def19;
then consider v being set  such that
A1: the_Vertices_of G = {v} by CARD_2:42;
reconsider v = v as Vertex of G by A1, TARSKI:def_1;
take  v ; ::_thesis: the_Vertices_of G = {v}
thus  the_Vertices_of G = {v} by A1; ::_thesis: verum
end;

theorem :: GLIB_000:23
for G being loopless trivial _Graph holds the_Edges_of G = {}
proof
let G be loopless trivial _Graph; ::_thesis: the_Edges_of G = {}
consider v being Vertex of G such that
A1: the_Vertices_of G = {v} by Th22;
now__::_thesis:_not_the_Edges_of_G_<>_{}
assume  the_Edges_of G <> {} ; ::_thesis: contradiction
then consider e being set  such that
A2: e in the_Edges_of G by XBOOLE_0:def_1;
 (the_Target_of G) . e in {v} by A1, A2, FUNCT_2:5;
then A3: (the_Target_of G) . e = v by TARSKI:def_1;
 (the_Source_of G) . e in {v} by A1, A2, FUNCT_2:5;
then  (the_Source_of G) . e = v by TARSKI:def_1;
hence  contradiction by A2, A3, Def18; ::_thesis: verum
end;
hence  the_Edges_of G = {} ; ::_thesis: verum
end;

theorem :: GLIB_000:24
for G being _Graph st the_Edges_of G = {} holds
G is simple
proof
let G be _Graph; ::_thesis: ( the_Edges_of G = {} implies G is simple )
assume A1: the_Edges_of G = {} ; ::_thesis: G is simple
then  for e being set holds
( not e in the_Edges_of G or not (the_Source_of G) . e = (the_Target_of G) . e ) ;
then A2: G is loopless by Def18;
 for e1, e2, v1, v2 being set st e1 Joins v1,v2,G & e2 Joins v1,v2,G holds
e1 = e2 by A1, Def13;
then  G is non-multi by Def20;
hence  G is simple by A2; ::_thesis: verum
end;

theorem :: GLIB_000:25
for G being finite _Graph holds G .order() >= 1
proof
let G be finite _Graph; ::_thesis: G .order() >= 1
 0 + 1 < (G .order()) + 1 by NAT_1:3, XREAL_1:8;
hence  G .order() >= 1 by NAT_1:13; ::_thesis: verum
end;

theorem :: GLIB_000:26
for G being finite _Graph holds
( G .order() = 1 iff G is trivial ) by Def19;

theorem :: GLIB_000:27
for G being finite _Graph holds
( G .order() = 1 iff ex v being Vertex of G st the_Vertices_of G = {v} )
proof
let G be finite _Graph; ::_thesis: ( G .order() = 1 iff ex v being Vertex of G st the_Vertices_of G = {v} )
hereby  ::_thesis: ( ex v being Vertex of G st the_Vertices_of G = {v} implies G .order() = 1 )
assume  G .order() = 1 ; ::_thesis: ex v being Vertex of G st the_Vertices_of G = {v}
then consider v being set  such that
A1: the_Vertices_of G = {v} by CARD_2:42;
reconsider v = v as Vertex of G by A1, TARSKI:def_1;
take v = v; ::_thesis: the_Vertices_of G = {v}
thus  the_Vertices_of G = {v} by A1; ::_thesis: verum
end;
given v being Vertex of G such that A2: the_Vertices_of G = {v} ; ::_thesis: G .order() = 1
thus  G .order() = 1 by A2, CARD_1:30; ::_thesis: verum
end;

theorem Th28: :: GLIB_000:28
for G being _Graph
for e, X being set holds
( ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ) iff e in G .edgesInOut X )
proof
let G be _Graph; ::_thesis: for e, X being set holds
( ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ) iff e in G .edgesInOut X )
let e, X be set ; ::_thesis: ( ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ) iff e in G .edgesInOut X )
hereby  ::_thesis: ( e in G .edgesInOut X implies ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ) )
assume that
A1: e in the_Edges_of G and
A2: ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ; ::_thesis: e in G .edgesInOut X
now__::_thesis:_e_in_G_.edgesInOut_X
percases ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) by A2;
suppose (the_Source_of G) . e in X ; ::_thesis: e in G .edgesInOut X
then  e in G .edgesOutOf X by A1, Def27;
hence  e in G .edgesInOut X by XBOOLE_0:def_3; ::_thesis: verum
end;
suppose (the_Target_of G) . e in X ; ::_thesis: e in G .edgesInOut X
then  e in G .edgesInto X by A1, Def26;
hence  e in G .edgesInOut X by XBOOLE_0:def_3; ::_thesis: verum
end;
end;
end;
hence  e in G .edgesInOut X ; ::_thesis: verum
end;
assume  e in G .edgesInOut X ; ::_thesis: ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) )
then  ( e in G .edgesInto X or e in G .edgesOutOf X ) by XBOOLE_0:def_3;
hence  ( e in the_Edges_of G & ( (the_Source_of G) . e in X or (the_Target_of G) . e in X ) ) by Def26, Def27; ::_thesis: verum
end;

theorem :: GLIB_000:29
for G being _Graph
for X being set holds
( G .edgesInto X c= G .edgesInOut X & G .edgesOutOf X c= G .edgesInOut X )
proof
let G be _Graph; ::_thesis: for X being set holds
( G .edgesInto X c= G .edgesInOut X & G .edgesOutOf X c= G .edgesInOut X )
let X be set ; ::_thesis: ( G .edgesInto X c= G .edgesInOut X & G .edgesOutOf X c= G .edgesInOut X )
 for z being set st z in G .edgesInto X holds
z in G .edgesInOut X by XBOOLE_0:def_3;
hence  G .edgesInto X c= G .edgesInOut X by TARSKI:def_3; ::_thesis: G .edgesOutOf X c= G .edgesInOut X
 for z being set st z in G .edgesOutOf X holds
z in G .edgesInOut X by XBOOLE_0:def_3;
hence  G .edgesOutOf X c= G .edgesInOut X by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:30
for G being _Graph holds the_Edges_of G = G .edgesInOut (the_Vertices_of G)
proof
let G be _Graph; ::_thesis: the_Edges_of G = G .edgesInOut (the_Vertices_of G)
set EG = the_Edges_of G;
set SG = the_Source_of G;
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_the_Edges_of_G_implies_x_in_G_.edgesInOut_(the_Vertices_of_G)_)_&_(_x_in_G_.edgesInOut_(the_Vertices_of_G)_implies_x_in_the_Edges_of_G_)_)
let x be set ; ::_thesis: ( ( x in the_Edges_of G implies x in G .edgesInOut (the_Vertices_of G) ) & ( x in G .edgesInOut (the_Vertices_of G) implies x in the_Edges_of G ) )
hereby  ::_thesis: ( x in G .edgesInOut (the_Vertices_of G) implies x in the_Edges_of G )
assume A1: x in the_Edges_of G ; ::_thesis: x in G .edgesInOut (the_Vertices_of G)
then  (the_Source_of G) . x in the_Vertices_of G by FUNCT_2:5;
hence  x in G .edgesInOut (the_Vertices_of G) by A1, Th28; ::_thesis: verum
end;
assume  x in G .edgesInOut (the_Vertices_of G) ; ::_thesis: x in the_Edges_of G
hence  x in the_Edges_of G ; ::_thesis: verum
end;
hence  the_Edges_of G = G .edgesInOut (the_Vertices_of G) by TARSKI:1; ::_thesis: verum
end;

theorem :: GLIB_000:31
for G being _Graph
for e, X being set holds
( ( e in the_Edges_of G & (the_Source_of G) . e in X & (the_Target_of G) . e in X ) iff e in G .edgesBetween X ) by Lm6;

theorem :: GLIB_000:32
for G being _Graph
for x, X, y, e being set st x in X & y in X & e Joins x,y,G holds
e in G .edgesBetween X
proof
let G be _Graph; ::_thesis: for x, X, y, e being set st x in X & y in X & e Joins x,y,G holds
e in G .edgesBetween X
let x, X, y, e be set ; ::_thesis: ( x in X & y in X & e Joins x,y,G implies e in G .edgesBetween X )
assume that
A1: ( x in X & y in X ) and
A2: e Joins x,y,G ; ::_thesis: e in G .edgesBetween X
A3: ( ( (the_Source_of G) . e = x & (the_Target_of G) . e = y ) or ( (the_Source_of G) . e = y & (the_Target_of G) . e = x ) ) by A2, Def13;
 e in the_Edges_of G by A2, Def13;
hence  e in G .edgesBetween X by A1, A3, Lm6; ::_thesis: verum
end;

theorem :: GLIB_000:33
for G being _Graph
for X being set holds G .edgesBetween X c= G .edgesInOut X
proof
let G be _Graph; ::_thesis: for X being set holds G .edgesBetween X c= G .edgesInOut X
let X be set ; ::_thesis: G .edgesBetween X c= G .edgesInOut X
now__::_thesis:_for_z_being_set_st_z_in_G_.edgesBetween_X_holds_
z_in_G_.edgesInOut_X
let z be set ; ::_thesis: ( z in G .edgesBetween X implies z in G .edgesInOut X )
assume  z in G .edgesBetween X ; ::_thesis: z in G .edgesInOut X
then  z in G .edgesInto X by XBOOLE_0:def_4;
hence  z in G .edgesInOut X by XBOOLE_0:def_3; ::_thesis: verum
end;
hence  G .edgesBetween X c= G .edgesInOut X by TARSKI:def_3; ::_thesis: verum
end;

theorem Th34: :: GLIB_000:34
for G being _Graph holds the_Edges_of G = G .edgesBetween (the_Vertices_of G)
proof
let G be _Graph; ::_thesis: the_Edges_of G = G .edgesBetween (the_Vertices_of G)
set EG = the_Edges_of G;
set SG = the_Source_of G;
set TG = the_Target_of G;
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_the_Edges_of_G_implies_x_in_G_.edgesBetween_(the_Vertices_of_G)_)_&_(_x_in_G_.edgesBetween_(the_Vertices_of_G)_implies_x_in_the_Edges_of_G_)_)
let x be set ; ::_thesis: ( ( x in the_Edges_of G implies x in G .edgesBetween (the_Vertices_of G) ) & ( x in G .edgesBetween (the_Vertices_of G) implies x in the_Edges_of G ) )
hereby  ::_thesis: ( x in G .edgesBetween (the_Vertices_of G) implies x in the_Edges_of G )
assume A1: x in the_Edges_of G ; ::_thesis: x in G .edgesBetween (the_Vertices_of G)
then  ( (the_Source_of G) . x in the_Vertices_of G & (the_Target_of G) . x in the_Vertices_of G ) by FUNCT_2:5;
hence  x in G .edgesBetween (the_Vertices_of G) by A1, Lm6; ::_thesis: verum
end;
assume  x in G .edgesBetween (the_Vertices_of G) ; ::_thesis: x in the_Edges_of G
hence  x in the_Edges_of G ; ::_thesis: verum
end;
hence  the_Edges_of G = G .edgesBetween (the_Vertices_of G) by TARSKI:1; ::_thesis: verum
end;

theorem Th35: :: GLIB_000:35
for G being _Graph
for X being set holds (the_Edges_of G) \ (G .edgesInOut X) = G .edgesBetween ((the_Vertices_of G) \ X)
proof
let G be _Graph; ::_thesis: for X being set holds (the_Edges_of G) \ (G .edgesInOut X) = G .edgesBetween ((the_Vertices_of G) \ X)
let X be set ; ::_thesis: (the_Edges_of G) \ (G .edgesInOut X) = G .edgesBetween ((the_Vertices_of G) \ X)
set EG = the_Edges_of G;
set VG = the_Vertices_of G;
set EIO = G .edgesInOut X;
set EB = G .edgesBetween ((the_Vertices_of G) \ X);
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_(the_Edges_of_G)_\_(G_.edgesInOut_X)_implies_x_in_G_.edgesBetween_((the_Vertices_of_G)_\_X)_)_&_(_x_in_G_.edgesBetween_((the_Vertices_of_G)_\_X)_implies_x_in_(the_Edges_of_G)_\_(G_.edgesInOut_X)_)_)
let x be set ; ::_thesis: ( ( x in (the_Edges_of G) \ (G .edgesInOut X) implies x in G .edgesBetween ((the_Vertices_of G) \ X) ) & ( x in G .edgesBetween ((the_Vertices_of G) \ X) implies x in (the_Edges_of G) \ (G .edgesInOut X) ) )
hereby  ::_thesis: ( x in G .edgesBetween ((the_Vertices_of G) \ X) implies x in (the_Edges_of G) \ (G .edgesInOut X) )
assume A1: x in (the_Edges_of G) \ (G .edgesInOut X) ; ::_thesis: x in G .edgesBetween ((the_Vertices_of G) \ X)
then A2: (the_Target_of G) . x in the_Vertices_of G by FUNCT_2:5;
A3: not x in G .edgesInOut X by A1, XBOOLE_0:def_5;
then  not (the_Target_of G) . x in X by A1, Th28;
then A4: (the_Target_of G) . x in (the_Vertices_of G) \ X by A2, XBOOLE_0:def_5;
A5: (the_Source_of G) . x in the_Vertices_of G by A1, FUNCT_2:5;
 not (the_Source_of G) . x in X by A1, A3, Th28;
then  (the_Source_of G) . x in (the_Vertices_of G) \ X by A5, XBOOLE_0:def_5;
hence  x in G .edgesBetween ((the_Vertices_of G) \ X) by A1, A4, Lm6; ::_thesis: verum
end;
assume A6: x in G .edgesBetween ((the_Vertices_of G) \ X) ; ::_thesis: x in (the_Edges_of G) \ (G .edgesInOut X)
then  (the_Target_of G) . x in (the_Vertices_of G) \ X by Lm6;
then A7: not (the_Target_of G) . x in X by XBOOLE_0:def_5;
 (the_Source_of G) . x in (the_Vertices_of G) \ X by A6, Lm6;
then  not (the_Source_of G) . x in X by XBOOLE_0:def_5;
then  not x in G .edgesInOut X by A7, Th28;
hence  x in (the_Edges_of G) \ (G .edgesInOut X) by A6, XBOOLE_0:def_5; ::_thesis: verum
end;
hence  (the_Edges_of G) \ (G .edgesInOut X) = G .edgesBetween ((the_Vertices_of G) \ X) by TARSKI:1; ::_thesis: verum
end;

theorem :: GLIB_000:36
for G being _Graph
for X, Y being set st X c= Y holds
G .edgesBetween X c= G .edgesBetween Y
proof
let G be _Graph; ::_thesis: for X, Y being set st X c= Y holds
G .edgesBetween X c= G .edgesBetween Y
let X, Y be set ; ::_thesis: ( X c= Y implies G .edgesBetween X c= G .edgesBetween Y )
assume A1: X c= Y ; ::_thesis: G .edgesBetween X c= G .edgesBetween Y
now__::_thesis:_for_x_being_set_st_x_in_G_.edgesBetween_X_holds_
x_in_G_.edgesBetween_Y
let x be set ; ::_thesis: ( x in G .edgesBetween X implies x in G .edgesBetween Y )
assume A2: x in G .edgesBetween X ; ::_thesis: x in G .edgesBetween Y
then  ( (the_Source_of G) . x in X & (the_Target_of G) . x in X ) by Lm6;
hence  x in G .edgesBetween Y by A1, A2, Lm6; ::_thesis: verum
end;
hence  G .edgesBetween X c= G .edgesBetween Y by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:37
for G being _Graph
for X1, X2, Y1, Y2 being set st X1 c= X2 & Y1 c= Y2 holds
G .edgesBetween (X1,Y1) c= G .edgesBetween (X2,Y2)
proof
let G be _Graph; ::_thesis: for X1, X2, Y1, Y2 being set st X1 c= X2 & Y1 c= Y2 holds
G .edgesBetween (X1,Y1) c= G .edgesBetween (X2,Y2)
let X1, X2, Y1, Y2 be set ; ::_thesis: ( X1 c= X2 & Y1 c= Y2 implies G .edgesBetween (X1,Y1) c= G .edgesBetween (X2,Y2) )
assume A1: ( X1 c= X2 & Y1 c= Y2 ) ; ::_thesis: G .edgesBetween (X1,Y1) c= G .edgesBetween (X2,Y2)
now__::_thesis:_for_e_being_set_st_e_in_G_.edgesBetween_(X1,Y1)_holds_
e_in_G_.edgesBetween_(X2,Y2)
let e be set ; ::_thesis: ( e in G .edgesBetween (X1,Y1) implies e in G .edgesBetween (X2,Y2) )
assume A2: e in G .edgesBetween (X1,Y1) ; ::_thesis: e in G .edgesBetween (X2,Y2)
then  e SJoins X1,Y1,G by Def30;
then  ( ( (the_Source_of G) . e in X1 & (the_Target_of G) . e in Y1 ) or ( (the_Source_of G) . e in Y1 & (the_Target_of G) . e in X1 ) ) by Def15;
then  e SJoins X2,Y2,G by A1, A2, Def15;
hence  e in G .edgesBetween (X2,Y2) by Def30; ::_thesis: verum
end;
hence  G .edgesBetween (X1,Y1) c= G .edgesBetween (X2,Y2) by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:38
for G being _Graph
for X1, X2, Y1, Y2 being set st X1 c= X2 & Y1 c= Y2 holds
G .edgesDBetween (X1,Y1) c= G .edgesDBetween (X2,Y2)
proof
let G be _Graph; ::_thesis: for X1, X2, Y1, Y2 being set st X1 c= X2 & Y1 c= Y2 holds
G .edgesDBetween (X1,Y1) c= G .edgesDBetween (X2,Y2)
let X1, X2, Y1, Y2 be set ; ::_thesis: ( X1 c= X2 & Y1 c= Y2 implies G .edgesDBetween (X1,Y1) c= G .edgesDBetween (X2,Y2) )
assume A1: ( X1 c= X2 & Y1 c= Y2 ) ; ::_thesis: G .edgesDBetween (X1,Y1) c= G .edgesDBetween (X2,Y2)
now__::_thesis:_for_e_being_set_st_e_in_G_.edgesDBetween_(X1,Y1)_holds_
e_in_G_.edgesDBetween_(X2,Y2)
let e be set ; ::_thesis: ( e in G .edgesDBetween (X1,Y1) implies e in G .edgesDBetween (X2,Y2) )
assume A2: e in G .edgesDBetween (X1,Y1) ; ::_thesis: e in G .edgesDBetween (X2,Y2)
then  e DSJoins X1,Y1,G by Def31;
then  ( (the_Source_of G) . e in X1 & (the_Target_of G) . e in Y1 ) by Def16;
then  e DSJoins X2,Y2,G by A1, A2, Def16;
hence  e in G .edgesDBetween (X2,Y2) by Def31; ::_thesis: verum
end;
hence  G .edgesDBetween (X1,Y1) c= G .edgesDBetween (X2,Y2) by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:39
for G being _Graph
for v being Vertex of G holds
( v .edgesIn() = G .edgesDBetween ((the_Vertices_of G),{v}) & v .edgesOut() = G .edgesDBetween ({v},(the_Vertices_of G)) )
proof
let G be _Graph; ::_thesis: for v being Vertex of G holds
( v .edgesIn() = G .edgesDBetween ((the_Vertices_of G),{v}) & v .edgesOut() = G .edgesDBetween ({v},(the_Vertices_of G)) )
let v be Vertex of G; ::_thesis: ( v .edgesIn() = G .edgesDBetween ((the_Vertices_of G),{v}) & v .edgesOut() = G .edgesDBetween ({v},(the_Vertices_of G)) )
now__::_thesis:_for_e_being_set_holds_
(_(_e_in_v_.edgesIn()_implies_e_in_G_.edgesDBetween_((the_Vertices_of_G),{v})_)_&_(_e_in_G_.edgesDBetween_((the_Vertices_of_G),{v})_implies_e_in_v_.edgesIn()_)_)
let e be set ; ::_thesis: ( ( e in v .edgesIn() implies e in G .edgesDBetween ((the_Vertices_of G),{v}) ) & ( e in G .edgesDBetween ((the_Vertices_of G),{v}) implies e in v .edgesIn() ) )
hereby  ::_thesis: ( e in G .edgesDBetween ((the_Vertices_of G),{v}) implies e in v .edgesIn() )
assume A1: e in v .edgesIn() ; ::_thesis: e in G .edgesDBetween ((the_Vertices_of G),{v})
then  (the_Target_of G) . e = v by Lm8;
then A2: (the_Target_of G) . e in {v} by TARSKI:def_1;
 (the_Source_of G) . e in the_Vertices_of G by A1, FUNCT_2:5;
then  e DSJoins the_Vertices_of G,{v},G by A1, A2, Def16;
hence  e in G .edgesDBetween ((the_Vertices_of G),{v}) by Def31; ::_thesis: verum
end;
assume A3: e in G .edgesDBetween ((the_Vertices_of G),{v}) ; ::_thesis: e in v .edgesIn()
then  e DSJoins the_Vertices_of G,{v},G by Def31;
then  (the_Target_of G) . e in {v} by Def16;
then  (the_Target_of G) . e = v by TARSKI:def_1;
hence  e in v .edgesIn() by A3, Lm8; ::_thesis: verum
end;
hence  v .edgesIn() = G .edgesDBetween ((the_Vertices_of G),{v}) by TARSKI:1; ::_thesis: v .edgesOut() = G .edgesDBetween ({v},(the_Vertices_of G))
now__::_thesis:_for_e_being_set_holds_
(_(_e_in_v_.edgesOut()_implies_e_in_G_.edgesDBetween_({v},(the_Vertices_of_G))_)_&_(_e_in_G_.edgesDBetween_({v},(the_Vertices_of_G))_implies_e_in_v_.edgesOut()_)_)
let e be set ; ::_thesis: ( ( e in v .edgesOut() implies e in G .edgesDBetween ({v},(the_Vertices_of G)) ) & ( e in G .edgesDBetween ({v},(the_Vertices_of G)) implies e in v .edgesOut() ) )
hereby  ::_thesis: ( e in G .edgesDBetween ({v},(the_Vertices_of G)) implies e in v .edgesOut() )
assume A4: e in v .edgesOut() ; ::_thesis: e in G .edgesDBetween ({v},(the_Vertices_of G))
then  (the_Source_of G) . e = v by Lm9;
then A5: (the_Source_of G) . e in {v} by TARSKI:def_1;
 (the_Target_of G) . e in the_Vertices_of G by A4, FUNCT_2:5;
then  e DSJoins {v}, the_Vertices_of G,G by A4, A5, Def16;
hence  e in G .edgesDBetween ({v},(the_Vertices_of G)) by Def31; ::_thesis: verum
end;
assume A6: e in G .edgesDBetween ({v},(the_Vertices_of G)) ; ::_thesis: e in v .edgesOut()
then  e DSJoins {v}, the_Vertices_of G,G by Def31;
then  (the_Source_of G) . e in {v} by Def16;
then  (the_Source_of G) . e = v by TARSKI:def_1;
hence  e in v .edgesOut() by A6, Lm9; ::_thesis: verum
end;
hence  v .edgesOut() = G .edgesDBetween ({v},(the_Vertices_of G)) by TARSKI:1; ::_thesis: verum
end;

theorem :: GLIB_000:40
for G being _Graph holds G is Subgraph of G by Lm4;

theorem Th41: :: GLIB_000:41
for G1, G2 being _Graph holds
( G1 is Subgraph of G2 & G2 is Subgraph of G1 iff ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) )
proof
let G1, G2 be _Graph; ::_thesis: ( G1 is Subgraph of G2 & G2 is Subgraph of G1 iff ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) )
hereby  ::_thesis: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 implies ( G1 is Subgraph of G2 & G2 is Subgraph of G1 ) )
assume that
A1: G1 is Subgraph of G2 and
A2: G2 is Subgraph of G1 ; ::_thesis: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 )
A3: ( the_Vertices_of G2 c= the_Vertices_of G1 & the_Edges_of G2 c= the_Edges_of G1 ) by A2, Def32;
 ( the_Vertices_of G1 c= the_Vertices_of G2 & the_Edges_of G1 c= the_Edges_of G2 ) by A1, Def32;
hence A4: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 ) by A3, XBOOLE_0:def_10; ::_thesis: ( the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 )
then A5: ( dom (the_Source_of G1) = the_Edges_of G1 & dom (the_Source_of G2) = the_Edges_of G1 ) by FUNCT_2:def_1;
 for e being set st e in dom (the_Source_of G1) holds
(the_Source_of G1) . e = (the_Source_of G2) . e by A1, Def32;
hence  the_Source_of G1 = the_Source_of G2 by A5, FUNCT_1:2; ::_thesis: the_Target_of G1 = the_Target_of G2
A6: ( dom (the_Target_of G1) = the_Edges_of G1 & dom (the_Target_of G2) = the_Edges_of G1 ) by A4, FUNCT_2:def_1;
 for e being set st e in dom (the_Target_of G1) holds
(the_Target_of G1) . e = (the_Target_of G2) . e by A1, Def32;
hence  the_Target_of G1 = the_Target_of G2 by A6, FUNCT_1:2; ::_thesis: verum
end;
assume that
A7: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 ) and
A8: ( the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) ; ::_thesis: ( G1 is Subgraph of G2 & G2 is Subgraph of G1 )
 for e being set st e in the_Edges_of G1 holds
( (the_Source_of G1) . e = (the_Source_of G2) . e & (the_Target_of G1) . e = (the_Target_of G2) . e ) by A8;
hence  ( G1 is Subgraph of G2 & G2 is Subgraph of G1 ) by A7, Def32; ::_thesis: verum
end;

theorem :: GLIB_000:42
for G1 being _Graph
for G2 being Subgraph of G1
for x being set holds
( ( x in the_Vertices_of G2 implies x in the_Vertices_of G1 ) & ( x in the_Edges_of G2 implies x in the_Edges_of G1 ) ) ;

theorem Th43: :: GLIB_000:43
for G1 being _Graph
for G2 being Subgraph of G1
for G3 being Subgraph of G2 holds G3 is Subgraph of G1
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for G3 being Subgraph of G2 holds G3 is Subgraph of G1
let G2 be Subgraph of G1; ::_thesis: for G3 being Subgraph of G2 holds G3 is Subgraph of G1
let G3 be Subgraph of G2; ::_thesis: G3 is Subgraph of G1
A1: the_Edges_of G2 c= the_Edges_of G1 ;
A2: the_Vertices_of G3 c= the_Vertices_of G2 ;
now__::_thesis:_(_the_Vertices_of_G3_c=_the_Vertices_of_G1_&_the_Edges_of_G3_c=_the_Edges_of_G1_&_(_for_e_being_set_st_e_in_the_Edges_of_G3_holds_
(_(the_Source_of_G3)_._e_=_(the_Source_of_G1)_._e_&_(the_Target_of_G3)_._e_=_(the_Target_of_G1)_._e_)_)_)
thus  the_Vertices_of G3 c= the_Vertices_of G1 by A2, XBOOLE_1:1; ::_thesis: ( the_Edges_of G3 c= the_Edges_of G1 & ( for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of G1) . e & (the_Target_of G3) . e = (the_Target_of G1) . e ) ) )
thus  the_Edges_of G3 c= the_Edges_of G1 by A1, XBOOLE_1:1; ::_thesis: for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of G1) . e & (the_Target_of G3) . e = (the_Target_of G1) . e )
let e be set ; ::_thesis: ( e in the_Edges_of G3 implies ( (the_Source_of G3) . e = (the_Source_of G1) . e & (the_Target_of G3) . e = (the_Target_of G1) . e ) )
assume A3: e in the_Edges_of G3 ; ::_thesis: ( (the_Source_of G3) . e = (the_Source_of G1) . e & (the_Target_of G3) . e = (the_Target_of G1) . e )
hence (the_Source_of G3) . e = (the_Source_of G2) . e by Def32
.= (the_Source_of G1) . e by A3, Def32 ;
::_thesis: (the_Target_of G3) . e = (the_Target_of G1) . e
thus (the_Target_of G3) . e = (the_Target_of G2) . e by A3, Def32
.= (the_Target_of G1) . e by A3, Def32 ; ::_thesis: verum
end;
hence  G3 is Subgraph of G1 by Def32; ::_thesis: verum
end;

theorem Th44: :: GLIB_000:44
for G being _Graph
for G1, G2 being Subgraph of G st the_Vertices_of G1 c= the_Vertices_of G2 & the_Edges_of G1 c= the_Edges_of G2 holds
G1 is Subgraph of G2
proof
let G be _Graph; ::_thesis: for G1, G2 being Subgraph of G st the_Vertices_of G1 c= the_Vertices_of G2 & the_Edges_of G1 c= the_Edges_of G2 holds
G1 is Subgraph of G2
let G1, G2 be Subgraph of G; ::_thesis: ( the_Vertices_of G1 c= the_Vertices_of G2 & the_Edges_of G1 c= the_Edges_of G2 implies G1 is Subgraph of G2 )
assume that
A1: the_Vertices_of G1 c= the_Vertices_of G2 and
A2: the_Edges_of G1 c= the_Edges_of G2 ; ::_thesis: G1 is Subgraph of G2
now__::_thesis:_for_e_being_set_st_e_in_the_Edges_of_G1_holds_
(_(the_Source_of_G1)_._e_=_(the_Source_of_G2)_._e_&_(the_Target_of_G1)_._e_=_(the_Target_of_G2)_._e_)
let e be set ; ::_thesis: ( e in the_Edges_of G1 implies ( (the_Source_of G1) . e = (the_Source_of G2) . e & (the_Target_of G1) . e = (the_Target_of G2) . e ) )
assume A3: e in the_Edges_of G1 ; ::_thesis: ( (the_Source_of G1) . e = (the_Source_of G2) . e & (the_Target_of G1) . e = (the_Target_of G2) . e )
hence (the_Source_of G1) . e = (the_Source_of G) . e by Def32
.= (the_Source_of G2) . e by A2, A3, Def32 ;
::_thesis: (the_Target_of G1) . e = (the_Target_of G2) . e
thus (the_Target_of G1) . e = (the_Target_of G) . e by A3, Def32
.= (the_Target_of G2) . e by A2, A3, Def32 ; ::_thesis: verum
end;
hence  G1 is Subgraph of G2 by A1, A2, Def32; ::_thesis: verum
end;

theorem Th45: :: GLIB_000:45
for G1 being _Graph
for G2 being Subgraph of G1 holds
( the_Source_of G2 = (the_Source_of G1) | (the_Edges_of G2) & the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G2) )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1 holds
( the_Source_of G2 = (the_Source_of G1) | (the_Edges_of G2) & the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G2) )
let G2 be Subgraph of G1; ::_thesis: ( the_Source_of G2 = (the_Source_of G1) | (the_Edges_of G2) & the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G2) )
set S2 = (the_Source_of G1) | (the_Edges_of G2);
set T2 = (the_Target_of G1) | (the_Edges_of G2);
A1: now__::_thesis:_for_x_being_set_st_x_in_dom_(the_Source_of_G2)_holds_
(the_Source_of_G2)_._x_=_((the_Source_of_G1)_|_(the_Edges_of_G2))_._x
let x be set ; ::_thesis: ( x in dom (the_Source_of G2) implies (the_Source_of G2) . x = ((the_Source_of G1) | (the_Edges_of G2)) . x )
assume A2: x in dom (the_Source_of G2) ; ::_thesis: (the_Source_of G2) . x = ((the_Source_of G1) | (the_Edges_of G2)) . x
hence (the_Source_of G2) . x = (the_Source_of G1) . x by Def32
.= ((the_Source_of G1) | (the_Edges_of G2)) . x by A2, FUNCT_1:49 ;
::_thesis: verum
end;
 dom (the_Source_of G1) = the_Edges_of G1 by FUNCT_2:def_1;
then  ( dom (the_Source_of G2) = the_Edges_of G2 & dom ((the_Source_of G1) | (the_Edges_of G2)) = the_Edges_of G2 ) by FUNCT_2:def_1, RELAT_1:62;
hence  the_Source_of G2 = (the_Source_of G1) | (the_Edges_of G2) by A1, FUNCT_1:2; ::_thesis: the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G2)
A3: now__::_thesis:_for_x_being_set_st_x_in_dom_(the_Target_of_G2)_holds_
(the_Target_of_G2)_._x_=_((the_Target_of_G1)_|_(the_Edges_of_G2))_._x
let x be set ; ::_thesis: ( x in dom (the_Target_of G2) implies (the_Target_of G2) . x = ((the_Target_of G1) | (the_Edges_of G2)) . x )
assume A4: x in dom (the_Target_of G2) ; ::_thesis: (the_Target_of G2) . x = ((the_Target_of G1) | (the_Edges_of G2)) . x
hence (the_Target_of G2) . x = (the_Target_of G1) . x by Def32
.= ((the_Target_of G1) | (the_Edges_of G2)) . x by A4, FUNCT_1:49 ;
::_thesis: verum
end;
 dom (the_Target_of G1) = the_Edges_of G1 by FUNCT_2:def_1;
then  ( dom (the_Target_of G2) = the_Edges_of G2 & dom ((the_Target_of G1) | (the_Edges_of G2)) = the_Edges_of G2 ) by FUNCT_2:def_1, RELAT_1:62;
hence  the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G2) by A3, FUNCT_1:2; ::_thesis: verum
end;

theorem :: GLIB_000:46
for G being _Graph
for V1, V2, E1, E2 being set
for G1 being inducedSubgraph of G,V1,E1
for G2 being inducedSubgraph of G,V2,E2 st V2 c= V1 & E2 c= E1 & V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 holds
G2 is Subgraph of G1
proof
let G be _Graph; ::_thesis: for V1, V2, E1, E2 being set
for G1 being inducedSubgraph of G,V1,E1
for G2 being inducedSubgraph of G,V2,E2 st V2 c= V1 & E2 c= E1 & V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 holds
G2 is Subgraph of G1
let V1, V2, E1, E2 be set ; ::_thesis: for G1 being inducedSubgraph of G,V1,E1
for G2 being inducedSubgraph of G,V2,E2 st V2 c= V1 & E2 c= E1 & V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 holds
G2 is Subgraph of G1
let G1 be inducedSubgraph of G,V1,E1; ::_thesis: for G2 being inducedSubgraph of G,V2,E2 st V2 c= V1 & E2 c= E1 & V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 holds
G2 is Subgraph of G1
let G2 be inducedSubgraph of G,V2,E2; ::_thesis: ( V2 c= V1 & E2 c= E1 & V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 implies G2 is Subgraph of G1 )
assume that
A1: ( V2 c= V1 & E2 c= E1 ) and
A2: ( V2 is non empty Subset of (the_Vertices_of G) & E2 c= G .edgesBetween V2 ) ; ::_thesis: G2 is Subgraph of G1
A3: ( the_Vertices_of G2 = V2 & the_Edges_of G2 = E2 ) by A2, Def37;
now__::_thesis:_G2_is_Subgraph_of_G1
percases ( ( V1 is non empty Subset of (the_Vertices_of G) & E1 c= G .edgesBetween V1 ) or not V1 is non empty Subset of (the_Vertices_of G) or not E1 c= G .edgesBetween V1 ) ;
suppose ( V1 is non empty Subset of (the_Vertices_of G) & E1 c= G .edgesBetween V1 ) ; ::_thesis: G2 is Subgraph of G1
then  ( the_Vertices_of G1 = V1 & the_Edges_of G1 = E1 ) by Def37;
hence  G2 is Subgraph of G1 by A1, A3, Th44; ::_thesis: verum
end;
suppose ( not V1 is non empty Subset of (the_Vertices_of G) or not E1 c= G .edgesBetween V1 ) ; ::_thesis: G2 is Subgraph of G1
then  G1 == G by Def37;
then  ( the_Vertices_of G1 = the_Vertices_of G & the_Edges_of G1 = the_Edges_of G ) by Def34;
hence  G2 is Subgraph of G1 by A3, Th44; ::_thesis: verum
end;
end;
end;
hence  G2 is Subgraph of G1 ; ::_thesis: verum
end;

theorem Th47: :: GLIB_000:47
for G1 being non trivial _Graph
for v being Vertex of G1
for G2 being removeVertex of G1,v holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ {v} & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) )
proof
let G1 be non trivial _Graph; ::_thesis: for v being Vertex of G1
for G2 being removeVertex of G1,v holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ {v} & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) )
let v be Vertex of G1; ::_thesis: for G2 being removeVertex of G1,v holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ {v} & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) )
let G2 be removeVertex of G1,v; ::_thesis: ( the_Vertices_of G2 = (the_Vertices_of G1) \ {v} & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) )
set VG = the_Vertices_of G1;
set V = (the_Vertices_of G1) \ {v};
now__::_thesis:_not_(the_Vertices_of_G1)_\_{v}_is_empty
assume  (the_Vertices_of G1) \ {v} is empty ; ::_thesis: contradiction
then  the_Vertices_of G1 c= {v} by XBOOLE_1:37;
then  the_Vertices_of G1 = {v} by ZFMISC_1:33;
then  card (the_Vertices_of G1) = 1 by CARD_1:30;
hence  contradiction by Def19; ::_thesis: verum
end;
then reconsider V = (the_Vertices_of G1) \ {v} as non empty Subset of (the_Vertices_of G1) ;
 G2 is inducedSubgraph of G1,V ;
hence  ( the_Vertices_of G2 = (the_Vertices_of G1) \ {v} & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) ) by Def37; ::_thesis: verum
end;

theorem :: GLIB_000:48
for G1 being finite non trivial _Graph
for v being Vertex of G1
for G2 being removeVertex of G1,v holds
( (G2 .order()) + 1 = G1 .order() & (G2 .size()) + (card (v .edgesInOut())) = G1 .size() )
proof
let G1 be finite non trivial _Graph; ::_thesis: for v being Vertex of G1
for G2 being removeVertex of G1,v holds
( (G2 .order()) + 1 = G1 .order() & (G2 .size()) + (card (v .edgesInOut())) = G1 .size() )
let v be Vertex of G1; ::_thesis: for G2 being removeVertex of G1,v holds
( (G2 .order()) + 1 = G1 .order() & (G2 .size()) + (card (v .edgesInOut())) = G1 .size() )
let G2 be removeVertex of G1,v; ::_thesis: ( (G2 .order()) + 1 = G1 .order() & (G2 .size()) + (card (v .edgesInOut())) = G1 .size() )
set VG1 = the_Vertices_of G1;
set VG2 = the_Vertices_of G2;
set EG1 = the_Edges_of G1;
set EG2 = the_Edges_of G2;
set EV = v .edgesInOut() ;
A1: the_Vertices_of G2 = (the_Vertices_of G1) \ {v} by Th47;
 v in {v} by TARSKI:def_1;
then  not v in the_Vertices_of G2 by A1, XBOOLE_0:def_5;
then  card (((the_Vertices_of G1) \ {v}) \/ {v}) = (G2 .order()) + 1 by A1, CARD_2:41;
hence  (G2 .order()) + 1 = G1 .order() by XBOOLE_1:45; ::_thesis: (G2 .size()) + (card (v .edgesInOut())) = G1 .size()
A2: ( the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ {v}) & G1 .edgesBetween ((the_Vertices_of G1) \ {v}) = (the_Edges_of G1) \ (v .edgesInOut()) ) by Th35, Th47;
then  the_Edges_of G1 = (the_Edges_of G2) \/ (v .edgesInOut()) by XBOOLE_1:45;
hence  (G2 .size()) + (card (v .edgesInOut())) = G1 .size() by A2, CARD_2:40, XBOOLE_1:79; ::_thesis: verum
end;

theorem Th49: :: GLIB_000:49
for G1 being _Graph
for V being set
for G2 being removeVertices of G1,V st V c< the_Vertices_of G1 holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) )
proof
let G1 be _Graph; ::_thesis: for V being set
for G2 being removeVertices of G1,V st V c< the_Vertices_of G1 holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) )
let V be set ; ::_thesis: for G2 being removeVertices of G1,V st V c< the_Vertices_of G1 holds
( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) )
let G2 be removeVertices of G1,V; ::_thesis: ( V c< the_Vertices_of G1 implies ( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) ) )
set VG2 = (the_Vertices_of G1) \ V;
assume A1: V c< the_Vertices_of G1 ; ::_thesis: ( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) )
now__::_thesis:_not_(the_Vertices_of_G1)_\_V_is_empty
assume  (the_Vertices_of G1) \ V is empty ; ::_thesis: contradiction
then  the_Vertices_of G1 c= V by XBOOLE_1:37;
hence  contradiction by A1, XBOOLE_0:def_8; ::_thesis: verum
end;
then reconsider VG2 = (the_Vertices_of G1) \ V as non empty Subset of (the_Vertices_of G1) ;
 G2 is inducedSubgraph of G1,VG2 ;
hence  ( the_Vertices_of G2 = (the_Vertices_of G1) \ V & the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) ) by Def37; ::_thesis: verum
end;

theorem :: GLIB_000:50
for G1 being finite _Graph
for V being Subset of (the_Vertices_of G1)
for G2 being removeVertices of G1,V st V <> the_Vertices_of G1 holds
( (G2 .order()) + (card V) = G1 .order() & (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() )
proof
let G1 be finite _Graph; ::_thesis: for V being Subset of (the_Vertices_of G1)
for G2 being removeVertices of G1,V st V <> the_Vertices_of G1 holds
( (G2 .order()) + (card V) = G1 .order() & (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() )
let V be Subset of (the_Vertices_of G1); ::_thesis: for G2 being removeVertices of G1,V st V <> the_Vertices_of G1 holds
( (G2 .order()) + (card V) = G1 .order() & (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() )
let G2 be removeVertices of G1,V; ::_thesis: ( V <> the_Vertices_of G1 implies ( (G2 .order()) + (card V) = G1 .order() & (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() ) )
set VG1 = the_Vertices_of G1;
set VG2 = the_Vertices_of G2;
set EG1 = the_Edges_of G1;
set EG2 = the_Edges_of G2;
A1: G1 .edgesBetween ((the_Vertices_of G1) \ V) = (the_Edges_of G1) \ (G1 .edgesInOut V) by Th35;
assume  V <> the_Vertices_of G1 ; ::_thesis: ( (G2 .order()) + (card V) = G1 .order() & (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() )
then A2: V c< the_Vertices_of G1 by XBOOLE_0:def_8;
then A3: the_Vertices_of G2 = (the_Vertices_of G1) \ V by Th49;
then  card ((the_Vertices_of G2) \/ V) = (card (the_Vertices_of G2)) + (card V) by CARD_2:40, XBOOLE_1:79;
hence  (G2 .order()) + (card V) = G1 .order() by A3, XBOOLE_1:45; ::_thesis: (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size()
A4: the_Edges_of G2 = G1 .edgesBetween ((the_Vertices_of G1) \ V) by A2, Th49;
then  the_Edges_of G1 = (the_Edges_of G2) \/ (G1 .edgesInOut V) by A1, XBOOLE_1:45;
hence  (G2 .size()) + (card (G1 .edgesInOut V)) = G1 .size() by A4, A1, CARD_2:40, XBOOLE_1:79; ::_thesis: verum
end;

theorem Th51: :: GLIB_000:51
for G1 being _Graph
for e being set
for G2 being removeEdge of G1,e holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ {e} )
proof
let G1 be _Graph; ::_thesis: for e being set
for G2 being removeEdge of G1,e holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ {e} )
let e be set ; ::_thesis: for G2 being removeEdge of G1,e holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ {e} )
let G2 be removeEdge of G1,e; ::_thesis: ( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ {e} )
set V = the_Vertices_of G1;
 the_Vertices_of G1 c= the_Vertices_of G1 ;
then reconsider V = the_Vertices_of G1 as non empty Subset of (the_Vertices_of G1) ;
set E = (the_Edges_of G1) \ {e};
reconsider E = (the_Edges_of G1) \ {e} as Subset of (G1 .edgesBetween V) by Th34;
 G2 is inducedSubgraph of G1,V,E ;
hence  ( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ {e} ) by Def37; ::_thesis: verum
end;

theorem :: GLIB_000:52
for G1 being finite _Graph
for e being set
for G2 being removeEdge of G1,e holds
( G1 .order() = G2 .order() & ( e in the_Edges_of G1 implies (G2 .size()) + 1 = G1 .size() ) )
proof
let G1 be finite _Graph; ::_thesis: for e being set
for G2 being removeEdge of G1,e holds
( G1 .order() = G2 .order() & ( e in the_Edges_of G1 implies (G2 .size()) + 1 = G1 .size() ) )
let e be set ; ::_thesis: for G2 being removeEdge of G1,e holds
( G1 .order() = G2 .order() & ( e in the_Edges_of G1 implies (G2 .size()) + 1 = G1 .size() ) )
let G2 be removeEdge of G1,e; ::_thesis: ( G1 .order() = G2 .order() & ( e in the_Edges_of G1 implies (G2 .size()) + 1 = G1 .size() ) )
A1: the_Edges_of G2 = (the_Edges_of G1) \ {e} by Th51;
thus  G1 .order() = G2 .order() by Th51; ::_thesis: ( e in the_Edges_of G1 implies (G2 .size()) + 1 = G1 .size() )
assume  e in the_Edges_of G1 ; ::_thesis: (G2 .size()) + 1 = G1 .size()
then  for x being set st x in {e} holds
x in the_Edges_of G1 by TARSKI:def_1;
then  {e} c= the_Edges_of G1 by TARSKI:def_3;
then A2: the_Edges_of G1 = (the_Edges_of G2) \/ {e} by A1, XBOOLE_1:45;
 e in {e} by TARSKI:def_1;
then  not e in the_Edges_of G2 by A1, XBOOLE_0:def_5;
hence  (G2 .size()) + 1 = G1 .size() by A2, CARD_2:41; ::_thesis: verum
end;

theorem Th53: :: GLIB_000:53
for G1 being _Graph
for E being set
for G2 being removeEdges of G1,E holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ E )
proof
let G1 be _Graph; ::_thesis: for E being set
for G2 being removeEdges of G1,E holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ E )
let E be set ; ::_thesis: for G2 being removeEdges of G1,E holds
( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ E )
let G2 be removeEdges of G1,E; ::_thesis: ( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ E )
set V = the_Vertices_of G1;
 the_Vertices_of G1 c= the_Vertices_of G1 ;
then reconsider V = the_Vertices_of G1 as non empty Subset of (the_Vertices_of G1) ;
set E2 = (the_Edges_of G1) \ E;
reconsider E2 = (the_Edges_of G1) \ E as Subset of (G1 .edgesBetween V) by Th34;
 G2 is inducedSubgraph of G1,V,E2 ;
hence  ( the_Vertices_of G2 = the_Vertices_of G1 & the_Edges_of G2 = (the_Edges_of G1) \ E ) by Def37; ::_thesis: verum
end;

theorem :: GLIB_000:54
for G1 being finite _Graph
for E being set
for G2 being removeEdges of G1,E holds G1 .order() = G2 .order() by Th53;

theorem :: GLIB_000:55
for G1 being finite _Graph
for E being Subset of (the_Edges_of G1)
for G2 being removeEdges of G1,E holds (G2 .size()) + (card E) = G1 .size()
proof
let G1 be finite _Graph; ::_thesis: for E being Subset of (the_Edges_of G1)
for G2 being removeEdges of G1,E holds (G2 .size()) + (card E) = G1 .size()
let E be Subset of (the_Edges_of G1); ::_thesis: for G2 being removeEdges of G1,E holds (G2 .size()) + (card E) = G1 .size()
let G2 be removeEdges of G1,E; ::_thesis: (G2 .size()) + (card E) = G1 .size()
A1: the_Edges_of G2 = (the_Edges_of G1) \ E by Th53;
then  the_Edges_of G1 = (the_Edges_of G2) \/ E by XBOOLE_1:45;
hence  (G2 .size()) + (card E) = G1 .size() by A1, CARD_2:40, XBOOLE_1:79; ::_thesis: verum
end;

theorem :: GLIB_000:56
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesIn() iff ( e in the_Edges_of G & (the_Target_of G) . e = v ) ) by Lm8;

theorem :: GLIB_000:57
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesIn() iff ex x being set st e DJoins x,v,G )
proof
let G be _Graph; ::_thesis: for e being set
for v being Vertex of G holds
( e in v .edgesIn() iff ex x being set st e DJoins x,v,G )
let e be set ; ::_thesis: for v being Vertex of G holds
( e in v .edgesIn() iff ex x being set st e DJoins x,v,G )
let v be Vertex of G; ::_thesis: ( e in v .edgesIn() iff ex x being set st e DJoins x,v,G )
hereby  ::_thesis: ( ex x being set st e DJoins x,v,G implies e in v .edgesIn() )
set x = (the_Source_of G) . e;
assume A1: e in v .edgesIn() ; ::_thesis: ex x being set st e DJoins x,v,G
take x = (the_Source_of G) . e; ::_thesis: e DJoins x,v,G
 (the_Target_of G) . e = v by A1, Lm8;
hence  e DJoins x,v,G by A1, Def14; ::_thesis: verum
end;
given x being set  such that A2: e DJoins x,v,G ; ::_thesis: e in v .edgesIn()
 ( e in the_Edges_of G & (the_Target_of G) . e = v ) by A2, Def14;
hence  e in v .edgesIn() by Lm8; ::_thesis: verum
end;

theorem :: GLIB_000:58
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesOut() iff ( e in the_Edges_of G & (the_Source_of G) . e = v ) ) by Lm9;

theorem :: GLIB_000:59
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesOut() iff ex x being set st e DJoins v,x,G )
proof
let G be _Graph; ::_thesis: for e being set
for v being Vertex of G holds
( e in v .edgesOut() iff ex x being set st e DJoins v,x,G )
let e be set ; ::_thesis: for v being Vertex of G holds
( e in v .edgesOut() iff ex x being set st e DJoins v,x,G )
let v be Vertex of G; ::_thesis: ( e in v .edgesOut() iff ex x being set st e DJoins v,x,G )
hereby  ::_thesis: ( ex x being set st e DJoins v,x,G implies e in v .edgesOut() )
set x = (the_Target_of G) . e;
assume A1: e in v .edgesOut() ; ::_thesis: ex x being set st e DJoins v,x,G
take x = (the_Target_of G) . e; ::_thesis: e DJoins v,x,G
 (the_Source_of G) . e = v by A1, Lm9;
hence  e DJoins v,x,G by A1, Def14; ::_thesis: verum
end;
given x being set  such that A2: e DJoins v,x,G ; ::_thesis: e in v .edgesOut()
 ( e in the_Edges_of G & (the_Source_of G) . e = v ) by A2, Def14;
hence  e in v .edgesOut() by Lm9; ::_thesis: verum
end;

theorem :: GLIB_000:60
for G being _Graph
for v being Vertex of G holds v .edgesInOut() = (v .edgesIn()) \/ (v .edgesOut()) ;

theorem Th61: :: GLIB_000:61
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesInOut() iff ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) ) )
proof
let G be _Graph; ::_thesis: for e being set
for v being Vertex of G holds
( e in v .edgesInOut() iff ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) ) )
let e be set ; ::_thesis: for v being Vertex of G holds
( e in v .edgesInOut() iff ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) ) )
let v be Vertex of G; ::_thesis: ( e in v .edgesInOut() iff ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) ) )
hereby  ::_thesis: ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) implies e in v .edgesInOut() )
assume A1: e in v .edgesInOut() ; ::_thesis: ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) )
hence  e in the_Edges_of G ; ::_thesis: ( (the_Source_of G) . e = v or (the_Target_of G) . e = v )
 ( e in v .edgesIn() or e in v .edgesOut() ) by A1, XBOOLE_0:def_3;
hence  ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) by Lm8, Lm9; ::_thesis: verum
end;
assume  ( e in the_Edges_of G & ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) ) ; ::_thesis: e in v .edgesInOut()
then  ( e in v .edgesIn() or e in v .edgesOut() ) by Lm8, Lm9;
hence  e in v .edgesInOut() by XBOOLE_0:def_3; ::_thesis: verum
end;

theorem Th62: :: GLIB_000:62
for G being _Graph
for e, x being set
for v1 being Vertex of G st e Joins v1,x,G holds
e in v1 .edgesInOut()
proof
let G be _Graph; ::_thesis: for e, x being set
for v1 being Vertex of G st e Joins v1,x,G holds
e in v1 .edgesInOut()
let e, x be set ; ::_thesis: for v1 being Vertex of G st e Joins v1,x,G holds
e in v1 .edgesInOut()
let v1 be Vertex of G; ::_thesis: ( e Joins v1,x,G implies e in v1 .edgesInOut() )
assume A1: e Joins v1,x,G ; ::_thesis: e in v1 .edgesInOut()
then A2: ( ( (the_Source_of G) . e = v1 & (the_Target_of G) . e = x ) or ( (the_Source_of G) . e = x & (the_Target_of G) . e = v1 ) ) by Def13;
 e in the_Edges_of G by A1, Def13;
hence  e in v1 .edgesInOut() by A2, Th61; ::_thesis: verum
end;

theorem Th63: :: GLIB_000:63
for G being _Graph
for e being set
for v1, v2 being Vertex of G holds
( not e Joins v1,v2,G or ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
proof
let G be _Graph; ::_thesis: for e being set
for v1, v2 being Vertex of G holds
( not e Joins v1,v2,G or ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
let e be set ; ::_thesis: for v1, v2 being Vertex of G holds
( not e Joins v1,v2,G or ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
let v1, v2 be Vertex of G; ::_thesis: ( not e Joins v1,v2,G or ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
assume A1: e Joins v1,v2,G ; ::_thesis: ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
then A2: e in the_Edges_of G by Def13;
now__::_thesis:_(_(_e_in_v1_.edgesIn()_&_e_in_v2_.edgesOut()_)_or_(_e_in_v2_.edgesIn()_&_e_in_v1_.edgesOut()_)_)
percases ( ( (the_Source_of G) . e = v1 & (the_Target_of G) . e = v2 ) or ( (the_Source_of G) . e = v2 & (the_Target_of G) . e = v1 ) ) by A1, Def13;
suppose ( (the_Source_of G) . e = v1 & (the_Target_of G) . e = v2 ) ; ::_thesis: ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
hence  ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) ) by A2, Lm8, Lm9; ::_thesis: verum
end;
suppose ( (the_Source_of G) . e = v2 & (the_Target_of G) . e = v1 ) ; ::_thesis: ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) )
hence  ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) ) by A2, Lm8, Lm9; ::_thesis: verum
end;
end;
end;
hence  ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) ) ; ::_thesis: verum
end;

theorem :: GLIB_000:64
for G being _Graph
for e being set
for v1 being Vertex of G holds
( e in v1 .edgesInOut() iff ex v2 being Vertex of G st e Joins v1,v2,G )
proof
let G be _Graph; ::_thesis: for e being set
for v1 being Vertex of G holds
( e in v1 .edgesInOut() iff ex v2 being Vertex of G st e Joins v1,v2,G )
let e be set ; ::_thesis: for v1 being Vertex of G holds
( e in v1 .edgesInOut() iff ex v2 being Vertex of G st e Joins v1,v2,G )
let v1 be Vertex of G; ::_thesis: ( e in v1 .edgesInOut() iff ex v2 being Vertex of G st e Joins v1,v2,G )
hereby  ::_thesis: ( ex v2 being Vertex of G st e Joins v1,v2,G implies e in v1 .edgesInOut() )
assume A1: e in v1 .edgesInOut() ; ::_thesis: ex v2 being Vertex of G st e Joins v1,v2,G
now__::_thesis:_ex_v2_being_Vertex_of_G_st_e_Joins_v1,v2,G
percases ( (the_Source_of G) . e = v1 or (the_Target_of G) . e = v1 ) by A1, Th61;
supposeA2: (the_Source_of G) . e = v1 ; ::_thesis: ex v2 being Vertex of G st e Joins v1,v2,G
set v2 = (the_Target_of G) . e;
reconsider v2 = (the_Target_of G) . e as Vertex of G by A1, FUNCT_2:5;
take v2 = v2; ::_thesis: e Joins v1,v2,G
thus  e Joins v1,v2,G by A1, A2, Def13; ::_thesis: verum
end;
supposeA3: (the_Target_of G) . e = v1 ; ::_thesis: ex v2 being Vertex of G st e Joins v1,v2,G
set v2 = (the_Source_of G) . e;
reconsider v2 = (the_Source_of G) . e as Vertex of G by A1, FUNCT_2:5;
take v2 = v2; ::_thesis: e Joins v1,v2,G
thus  e Joins v1,v2,G by A1, A3, Def13; ::_thesis: verum
end;
end;
end;
hence  ex v2 being Vertex of G st e Joins v1,v2,G ; ::_thesis: verum
end;
given v2 being Vertex of G such that A4: e Joins v1,v2,G ; ::_thesis: e in v1 .edgesInOut()
thus  e in v1 .edgesInOut() by A4, Th62; ::_thesis: verum
end;

theorem :: GLIB_000:65
for G being _Graph
for e, x, y being set
for v being Vertex of G st e in v .edgesInOut() & e Joins x,y,G & not v = x holds
v = y
proof
let G be _Graph; ::_thesis: for e, x, y being set
for v being Vertex of G st e in v .edgesInOut() & e Joins x,y,G & not v = x holds
v = y
let e, x, y be set ; ::_thesis: for v being Vertex of G st e in v .edgesInOut() & e Joins x,y,G & not v = x holds
v = y
let v be Vertex of G; ::_thesis: ( e in v .edgesInOut() & e Joins x,y,G & not v = x implies v = y )
assume that
A1: e in v .edgesInOut() and
A2: e Joins x,y,G ; ::_thesis: ( v = x or v = y )
now__::_thesis:_(_v_<>_x_implies_v_=_y_)
assume A3: v <> x ; ::_thesis: v = y
now__::_thesis:_v_=_y
percases ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) by A1, Th61;
suppose (the_Source_of G) . e = v ; ::_thesis: v = y
hence  v = y by A2, A3, Def13; ::_thesis: verum
end;
suppose (the_Target_of G) . e = v ; ::_thesis: v = y
hence  v = y by A2, A3, Def13; ::_thesis: verum
end;
end;
end;
hence  v = y ; ::_thesis: verum
end;
hence  ( v = x or v = y ) ; ::_thesis: verum
end;

theorem :: GLIB_000:66
for G being _Graph
for e being set
for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( v1 .adj e = v2 & v2 .adj e = v1 )
proof
let G be _Graph; ::_thesis: for e being set
for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( v1 .adj e = v2 & v2 .adj e = v1 )
let e be set ; ::_thesis: for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( v1 .adj e = v2 & v2 .adj e = v1 )
let v1, v2 be Vertex of G; ::_thesis: ( e Joins v1,v2,G implies ( v1 .adj e = v2 & v2 .adj e = v1 ) )
assume A1: e Joins v1,v2,G ; ::_thesis: ( v1 .adj e = v2 & v2 .adj e = v1 )
then A2: e in v1 .edgesInOut() by Th62;
now__::_thesis:_(_v1_.adj_e_=_v2_&_v2_.adj_e_=_v1_)
percases ( ( (the_Source_of G) . e = v2 & (the_Target_of G) . e = v1 ) or ( (the_Source_of G) . e = v1 & (the_Target_of G) . e = v2 ) ) by A1, Def13;
supposeA3: ( (the_Source_of G) . e = v2 & (the_Target_of G) . e = v1 ) ; ::_thesis: ( v1 .adj e = v2 & v2 .adj e = v1 )
hence  v1 .adj e = v2 by A2, Def41; ::_thesis: v2 .adj e = v1
now__::_thesis:_v2_.adj_e_=_v1
percases ( v1 = v2 or v1 <> v2 ) ;
suppose v1 = v2 ; ::_thesis: v2 .adj e = v1
hence  v2 .adj e = v1 by A2, A3, Def41; ::_thesis: verum
end;
suppose v1 <> v2 ; ::_thesis: v2 .adj e = v1
hence  v2 .adj e = v1 by A2, A3, Def41; ::_thesis: verum
end;
end;
end;
hence  v2 .adj e = v1 ; ::_thesis: verum
end;
supposeA4: ( (the_Source_of G) . e = v1 & (the_Target_of G) . e = v2 ) ; ::_thesis: ( v1 .adj e = v2 & v2 .adj e = v1 )
now__::_thesis:_v1_.adj_e_=_v2
percases ( v1 = v2 or v1 <> v2 ) ;
suppose v1 = v2 ; ::_thesis: v1 .adj e = v2
hence  v1 .adj e = v2 by A2, A4, Def41; ::_thesis: verum
end;
suppose v1 <> v2 ; ::_thesis: v1 .adj e = v2
hence  v1 .adj e = v2 by A2, A4, Def41; ::_thesis: verum
end;
end;
end;
hence  v1 .adj e = v2 ; ::_thesis: v2 .adj e = v1
thus  v2 .adj e = v1 by A2, A4, Def41; ::_thesis: verum
end;
end;
end;
hence  ( v1 .adj e = v2 & v2 .adj e = v1 ) ; ::_thesis: verum
end;

theorem :: GLIB_000:67
for G being _Graph
for e being set
for v being Vertex of G holds
( e in v .edgesInOut() iff e Joins v,v .adj e,G )
proof
let G be _Graph; ::_thesis: for e being set
for v being Vertex of G holds
( e in v .edgesInOut() iff e Joins v,v .adj e,G )
let e be set ; ::_thesis: for v being Vertex of G holds
( e in v .edgesInOut() iff e Joins v,v .adj e,G )
let v be Vertex of G; ::_thesis: ( e in v .edgesInOut() iff e Joins v,v .adj e,G )
hereby  ::_thesis: ( e Joins v,v .adj e,G implies e in v .edgesInOut() )
assume A1: e in v .edgesInOut() ; ::_thesis: e Joins v,v .adj e,G
then A2: ( (the_Source_of G) . e = v or (the_Target_of G) . e = v ) by Th61;
now__::_thesis:_e_Joins_v,v_.adj_e,G
percases ( (the_Target_of G) . e = v or (the_Target_of G) . e <> v ) ;
supposeA3: (the_Target_of G) . e = v ; ::_thesis: e Joins v,v .adj e,G
then  v .adj e = (the_Source_of G) . e by A1, Def41;
hence  e Joins v,v .adj e,G by A1, A3, Def13; ::_thesis: verum
end;
supposeA4: (the_Target_of G) . e <> v ; ::_thesis: e Joins v,v .adj e,G
then  v .adj e = (the_Target_of G) . e by A1, A2, Def41;
hence  e Joins v,v .adj e,G by A1, A2, A4, Def13; ::_thesis: verum
end;
end;
end;
hence  e Joins v,v .adj e,G ; ::_thesis: verum
end;
assume  e Joins v,v .adj e,G ; ::_thesis: e in v .edgesInOut()
hence  e in v .edgesInOut() by Th62; ::_thesis: verum
end;

theorem :: GLIB_000:68
for G being finite _Graph
for e being set
for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( 1 <= v1 .degree() & 1 <= v2 .degree() )
proof
let G be finite _Graph; ::_thesis: for e being set
for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( 1 <= v1 .degree() & 1 <= v2 .degree() )
let e be set ; ::_thesis: for v1, v2 being Vertex of G st e Joins v1,v2,G holds
( 1 <= v1 .degree() & 1 <= v2 .degree() )
let v1, v2 be Vertex of G; ::_thesis: ( e Joins v1,v2,G implies ( 1 <= v1 .degree() & 1 <= v2 .degree() ) )
assume A1: e Joins v1,v2,G ; ::_thesis: ( 1 <= v1 .degree() & 1 <= v2 .degree() )
now__::_thesis:_(_1_<=_v1_.degree()_&_1_<=_v2_.degree()_)
percases ( ( e in v1 .edgesIn() & e in v2 .edgesOut() ) or ( e in v2 .edgesIn() & e in v1 .edgesOut() ) ) by A1, Th63;
supposeA2: ( e in v1 .edgesIn() & e in v2 .edgesOut() ) ; ::_thesis: ( 1 <= v1 .degree() & 1 <= v2 .degree() )
then  for x being set st x in {e} holds
x in v1 .edgesIn() by TARSKI:def_1;
then  {e} c= v1 .edgesIn() by TARSKI:def_3;
then  card {e} <= card (v1 .edgesIn()) by NAT_1:43;
then  1 <= v1 .inDegree() by CARD_1:30;
hence  1 <= v1 .degree() by NAT_1:12; ::_thesis: 1 <= v2 .degree()
 for x being set st x in {e} holds
x in v2 .edgesOut() by A2, TARSKI:def_1;
then  {e} c= v2 .edgesOut() by TARSKI:def_3;
then  card {e} <= card (v2 .edgesOut()) by NAT_1:43;
then  1 <= v2 .outDegree() by CARD_1:30;
hence  1 <= v2 .degree() by NAT_1:12; ::_thesis: verum
end;
supposeA3: ( e in v2 .edgesIn() & e in v1 .edgesOut() ) ; ::_thesis: ( 1 <= v1 .degree() & 1 <= v2 .degree() )
then  for x being set st x in {e} holds
x in v1 .edgesOut() by TARSKI:def_1;
then  {e} c= v1 .edgesOut() by TARSKI:def_3;
then  card {e} <= card (v1 .edgesOut()) by NAT_1:43;
then  1 <= v1 .outDegree() by CARD_1:30;
hence  1 <= v1 .degree() by NAT_1:12; ::_thesis: 1 <= v2 .degree()
 for x being set st x in {e} holds
x in v2 .edgesIn() by A3, TARSKI:def_1;
then  {e} c= v2 .edgesIn() by TARSKI:def_3;
then  card {e} <= card (v2 .edgesIn()) by NAT_1:43;
then  1 <= v2 .inDegree() by CARD_1:30;
hence  1 <= v2 .degree() by NAT_1:12; ::_thesis: verum
end;
end;
end;
hence  ( 1 <= v1 .degree() & 1 <= v2 .degree() ) ; ::_thesis: verum
end;

theorem Th69: :: GLIB_000:69
for G being _Graph
for x being set
for v being Vertex of G holds
( x in v .inNeighbors() iff ex e being set st e DJoins x,v,G )
proof
let G be _Graph; ::_thesis: for x being set
for v being Vertex of G holds
( x in v .inNeighbors() iff ex e being set st e DJoins x,v,G )
let x be set ; ::_thesis: for v being Vertex of G holds
( x in v .inNeighbors() iff ex e being set st e DJoins x,v,G )
let v be Vertex of G; ::_thesis: ( x in v .inNeighbors() iff ex e being set st e DJoins x,v,G )
hereby  ::_thesis: ( ex e being set st e DJoins x,v,G implies x in v .inNeighbors() )
assume  x in v .inNeighbors() ; ::_thesis: ex e being set st e DJoins x,v,G
then consider e being set  such that
A1: e in dom (the_Source_of G) and
A2: e in v .edgesIn() and
A3: x = (the_Source_of G) . e by FUNCT_1:def_6;
take e = e; ::_thesis: e DJoins x,v,G
 (the_Target_of G) . e = v by A2, Lm8;
hence  e DJoins x,v,G by A1, A3, Def14; ::_thesis: verum
end;
given e being set  such that A4: e DJoins x,v,G ; ::_thesis: x in v .inNeighbors()
A5: e in the_Edges_of G by A4, Def14;
then A6: e in dom (the_Source_of G) by FUNCT_2:def_1;
 (the_Target_of G) . e = v by A4, Def14;
then A7: e in v .edgesIn() by A5, Lm8;
 (the_Source_of G) . e = x by A4, Def14;
hence  x in v .inNeighbors() by A7, A6, FUNCT_1:def_6; ::_thesis: verum
end;

theorem Th70: :: GLIB_000:70
for G being _Graph
for x being set
for v being Vertex of G holds
( x in v .outNeighbors() iff ex e being set st e DJoins v,x,G )
proof
let G be _Graph; ::_thesis: for x being set
for v being Vertex of G holds
( x in v .outNeighbors() iff ex e being set st e DJoins v,x,G )
let x be set ; ::_thesis: for v being Vertex of G holds
( x in v .outNeighbors() iff ex e being set st e DJoins v,x,G )
let v be Vertex of G; ::_thesis: ( x in v .outNeighbors() iff ex e being set st e DJoins v,x,G )
hereby  ::_thesis: ( ex e being set st e DJoins v,x,G implies x in v .outNeighbors() )
assume  x in v .outNeighbors() ; ::_thesis: ex e being set st e DJoins v,x,G
then consider e being set  such that
A1: e in dom (the_Target_of G) and
A2: e in v .edgesOut() and
A3: x = (the_Target_of G) . e by FUNCT_1:def_6;
take e = e; ::_thesis: e DJoins v,x,G
 (the_Source_of G) . e = v by A2, Lm9;
hence  e DJoins v,x,G by A1, A3, Def14; ::_thesis: verum
end;
given e being set  such that A4: e DJoins v,x,G ; ::_thesis: x in v .outNeighbors()
A5: e in the_Edges_of G by A4, Def14;
then A6: e in dom (the_Target_of G) by FUNCT_2:def_1;
 (the_Source_of G) . e = v by A4, Def14;
then A7: e in v .edgesOut() by A5, Lm9;
 (the_Target_of G) . e = x by A4, Def14;
hence  x in v .outNeighbors() by A7, A6, FUNCT_1:def_6; ::_thesis: verum
end;

theorem Th71: :: GLIB_000:71
for G being _Graph
for x being set
for v being Vertex of G holds
( x in v .allNeighbors() iff ex e being set st e Joins v,x,G )
proof
let G be _Graph; ::_thesis: for x being set
for v being Vertex of G holds
( x in v .allNeighbors() iff ex e being set st e Joins v,x,G )
let x be set ; ::_thesis: for v being Vertex of G holds
( x in v .allNeighbors() iff ex e being set st e Joins v,x,G )
let v be Vertex of G; ::_thesis: ( x in v .allNeighbors() iff ex e being set st e Joins v,x,G )
hereby  ::_thesis: ( ex e being set st e Joins v,x,G implies x in v .allNeighbors() )
assume A1: x in v .allNeighbors() ; ::_thesis: ex e being set st e Joins v,x,G
now__::_thesis:_ex_e_being_set_st_e_Joins_v,x,G
percases ( x in v .inNeighbors() or x in v .outNeighbors() ) by A1, XBOOLE_0:def_3;
suppose x in v .inNeighbors() ; ::_thesis: ex e being set st e Joins v,x,G
then consider e being set  such that
A2: e DJoins x,v,G by Th69;
take e = e; ::_thesis: e Joins v,x,G
thus  e Joins v,x,G by A2, Lm2; ::_thesis: verum
end;
suppose x in v .outNeighbors() ; ::_thesis: ex e being set st e Joins v,x,G
then consider e being set  such that
A3: e DJoins v,x,G by Th70;
take e = e; ::_thesis: e Joins v,x,G
thus  e Joins v,x,G by A3, Lm2; ::_thesis: verum
end;
end;
end;
hence  ex e being set st e Joins v,x,G ; ::_thesis: verum
end;
assume  ex e being set st e Joins v,x,G ; ::_thesis: x in v .allNeighbors()
then consider e being set  such that
A4: e Joins v,x,G ;
now__::_thesis:_x_in_(v_.inNeighbors())_\/_(v_.outNeighbors())
percases ( e DJoins x,v,G or e DJoins v,x,G ) by A4, Lm2;
suppose e DJoins x,v,G ; ::_thesis: x in (v .inNeighbors()) \/ (v .outNeighbors())
then  x in v .inNeighbors() by Th69;
hence  x in (v .inNeighbors()) \/ (v .outNeighbors()) by XBOOLE_0:def_3; ::_thesis: verum
end;
suppose e DJoins v,x,G ; ::_thesis: x in (v .inNeighbors()) \/ (v .outNeighbors())
then  x in v .outNeighbors() by Th70;
hence  x in (v .inNeighbors()) \/ (v .outNeighbors()) by XBOOLE_0:def_3; ::_thesis: verum
end;
end;
end;
hence  x in v .allNeighbors() ; ::_thesis: verum
end;

theorem Th72: :: GLIB_000:72
for G1 being _Graph
for G2 being Subgraph of G1
for x, y, e being set holds
( ( e Joins x,y,G2 implies e Joins x,y,G1 ) & ( e DJoins x,y,G2 implies e DJoins x,y,G1 ) & ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for x, y, e being set holds
( ( e Joins x,y,G2 implies e Joins x,y,G1 ) & ( e DJoins x,y,G2 implies e DJoins x,y,G1 ) & ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
let G2 be Subgraph of G1; ::_thesis: for x, y, e being set holds
( ( e Joins x,y,G2 implies e Joins x,y,G1 ) & ( e DJoins x,y,G2 implies e DJoins x,y,G1 ) & ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
let x, y, e be set ; ::_thesis: ( ( e Joins x,y,G2 implies e Joins x,y,G1 ) & ( e DJoins x,y,G2 implies e DJoins x,y,G1 ) & ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
thus  ( e Joins x,y,G2 implies e Joins x,y,G1 ) by Lm5; ::_thesis: ( ( e DJoins x,y,G2 implies e DJoins x,y,G1 ) & ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
hereby  ::_thesis: ( ( e SJoins x,y,G2 implies e SJoins x,y,G1 ) & ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 ) )
assume A1: e DJoins x,y,G2 ; ::_thesis: e DJoins x,y,G1
then A2: e in the_Edges_of G2 by Def14;
 (the_Target_of G2) . e = y by A1, Def14;
then A3: (the_Target_of G1) . e = y by A2, Def32;
 (the_Source_of G2) . e = x by A1, Def14;
then  (the_Source_of G1) . e = x by A2, Def32;
hence  e DJoins x,y,G1 by A2, A3, Def14; ::_thesis: verum
end;
hereby  ::_thesis: ( e DSJoins x,y,G2 implies e DSJoins x,y,G1 )
assume A4: e SJoins x,y,G2 ; ::_thesis: e SJoins x,y,G1
then A5: ( ( (the_Source_of G2) . e in x & (the_Target_of G2) . e in y ) or ( (the_Source_of G2) . e in y & (the_Target_of G2) . e in x ) ) by Def15;
A6: e in the_Edges_of G2 by A4, Def15;
then  ( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) by Def32;
hence  e SJoins x,y,G1 by A6, A5, Def15; ::_thesis: verum
end;
assume A7: e DSJoins x,y,G2 ; ::_thesis: e DSJoins x,y,G1
then A8: ( (the_Source_of G2) . e in x & (the_Target_of G2) . e in y ) by Def16;
A9: e in the_Edges_of G2 by A7, Def16;
then  ( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) by Def32;
hence  e DSJoins x,y,G1 by A9, A8, Def16; ::_thesis: verum
end;

theorem :: GLIB_000:73
for G1 being _Graph
for G2 being Subgraph of G1
for x, y, e being set st e in the_Edges_of G2 holds
( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for x, y, e being set st e in the_Edges_of G2 holds
( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
let G2 be Subgraph of G1; ::_thesis: for x, y, e being set st e in the_Edges_of G2 holds
( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
let x, y, e be set ; ::_thesis: ( e in the_Edges_of G2 implies ( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) ) )
assume A1: e in the_Edges_of G2 ; ::_thesis: ( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
hereby  ::_thesis: ( ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
assume  e Joins x,y,G1 ; ::_thesis: e Joins x,y,G2
then A2: ( ( (the_Source_of G1) . e = x & (the_Target_of G1) . e = y ) or ( (the_Source_of G1) . e = y & (the_Target_of G1) . e = x ) ) by Def13;
 ( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) by A1, Def32;
hence  e Joins x,y,G2 by A1, A2, Def13; ::_thesis: verum
end;
 (the_Target_of G2) . e = ((the_Target_of G1) | (the_Edges_of G2)) . e by Th45;
then A3: (the_Target_of G2) . e = (the_Target_of G1) . e by A1, FUNCT_1:49;
hereby  ::_thesis: ( ( e SJoins x,y,G1 implies e SJoins x,y,G2 ) & ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 ) )
assume A4: e DJoins x,y,G1 ; ::_thesis: e DJoins x,y,G2
then  (the_Target_of G1) . e = y by Def14;
then A5: (the_Target_of G2) . e = y by A1, Def32;
 (the_Source_of G1) . e = x by A4, Def14;
then  (the_Source_of G2) . e = x by A1, Def32;
hence  e DJoins x,y,G2 by A1, A5, Def14; ::_thesis: verum
end;
hereby  ::_thesis: ( e DSJoins x,y,G1 implies e DSJoins x,y,G2 )
 (the_Target_of G2) . e = ((the_Target_of G1) | (the_Edges_of G2)) . e by Th45;
then A6: (the_Target_of G2) . e = (the_Target_of G1) . e by A1, FUNCT_1:49;
assume  e SJoins x,y,G1 ; ::_thesis: e SJoins x,y,G2
then A7: ( ( (the_Source_of G1) . e in x & (the_Target_of G1) . e in y ) or ( (the_Source_of G1) . e in y & (the_Target_of G1) . e in x ) ) by Def15;
 (the_Source_of G2) . e = ((the_Source_of G1) | (the_Edges_of G2)) . e by Th45;
then  (the_Source_of G2) . e = (the_Source_of G1) . e by A1, FUNCT_1:49;
hence  e SJoins x,y,G2 by A1, A7, A6, Def15; ::_thesis: verum
end;
assume  e DSJoins x,y,G1 ; ::_thesis: e DSJoins x,y,G2
then A8: ( (the_Source_of G1) . e in x & (the_Target_of G1) . e in y ) by Def16;
 (the_Source_of G2) . e = ((the_Source_of G1) | (the_Edges_of G2)) . e by Th45;
then  (the_Source_of G2) . e = (the_Source_of G1) . e by A1, FUNCT_1:49;
hence  e DSJoins x,y,G2 by A1, A8, A3, Def16; ::_thesis: verum
end;

theorem :: GLIB_000:74
for G1 being _Graph
for G2 being spanning Subgraph of G1
for G3 being spanning Subgraph of G2 holds G3 is spanning Subgraph of G1
proof
let G1 be _Graph; ::_thesis: for G2 being spanning Subgraph of G1
for G3 being spanning Subgraph of G2 holds G3 is spanning Subgraph of G1
let G2 be spanning Subgraph of G1; ::_thesis: for G3 being spanning Subgraph of G2 holds G3 is spanning Subgraph of G1
let G3 be spanning Subgraph of G2; ::_thesis: G3 is spanning Subgraph of G1
the_Vertices_of G3 = the_Vertices_of G2 by Def33
.= the_Vertices_of G1 by Def33 ;
hence  G3 is spanning Subgraph of G1 by Def33, Th43; ::_thesis: verum
end;

theorem :: GLIB_000:75
for G1 being finite _Graph
for G2 being Subgraph of G1 holds
( G2 .order() <= G1 .order() & G2 .size() <= G1 .size() )
proof
let G1 be finite _Graph; ::_thesis: for G2 being Subgraph of G1 holds
( G2 .order() <= G1 .order() & G2 .size() <= G1 .size() )
let G2 be Subgraph of G1; ::_thesis: ( G2 .order() <= G1 .order() & G2 .size() <= G1 .size() )
 card (the_Vertices_of G2) <= card (the_Vertices_of G1) by NAT_1:43;
hence  G2 .order() <= G1 .order() ; ::_thesis: G2 .size() <= G1 .size()
 card (the_Edges_of G2) <= card (the_Edges_of G1) by NAT_1:43;
hence  G2 .size() <= G1 .size() ; ::_thesis: verum
end;

theorem :: GLIB_000:76
for G1 being _Graph
for G2 being Subgraph of G1
for X being set holds
( G2 .edgesInto X c= G1 .edgesInto X & G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for X being set holds
( G2 .edgesInto X c= G1 .edgesInto X & G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
let G2 be Subgraph of G1; ::_thesis: for X being set holds
( G2 .edgesInto X c= G1 .edgesInto X & G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
let X be set ; ::_thesis: ( G2 .edgesInto X c= G1 .edgesInto X & G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
now__::_thesis:_for_e_being_set_st_e_in_G2_.edgesInto_X_holds_
e_in_G1_.edgesInto_X
let e be set ; ::_thesis: ( e in G2 .edgesInto X implies e in G1 .edgesInto X )
assume A1: e in G2 .edgesInto X ; ::_thesis: e in G1 .edgesInto X
then A2: (the_Target_of G2) . e = (the_Target_of G1) . e by Def32;
 ( e in the_Edges_of G2 & (the_Target_of G2) . e in X ) by A1, Def26;
hence  e in G1 .edgesInto X by A2, Def26; ::_thesis: verum
end;
hence A3: G2 .edgesInto X c= G1 .edgesInto X by TARSKI:def_3; ::_thesis: ( G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
then A4: G2 .edgesInto X c= G1 .edgesInOut X by XBOOLE_1:10;
now__::_thesis:_for_e_being_set_st_e_in_G2_.edgesOutOf_X_holds_
e_in_G1_.edgesOutOf_X
let e be set ; ::_thesis: ( e in G2 .edgesOutOf X implies e in G1 .edgesOutOf X )
assume A5: e in G2 .edgesOutOf X ; ::_thesis: e in G1 .edgesOutOf X
then A6: (the_Source_of G2) . e = (the_Source_of G1) . e by Def32;
 ( e in the_Edges_of G2 & (the_Source_of G2) . e in X ) by A5, Def27;
hence  e in G1 .edgesOutOf X by A6, Def27; ::_thesis: verum
end;
hence A7: G2 .edgesOutOf X c= G1 .edgesOutOf X by TARSKI:def_3; ::_thesis: ( G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )
then  G2 .edgesOutOf X c= G1 .edgesInOut X by XBOOLE_1:10;
hence  G2 .edgesInOut X c= G1 .edgesInOut X by A4, XBOOLE_1:8; ::_thesis: G2 .edgesBetween X c= G1 .edgesBetween X
thus  G2 .edgesBetween X c= G1 .edgesBetween X by A3, A7, XBOOLE_1:27; ::_thesis: verum
end;

theorem :: GLIB_000:77
for G1 being _Graph
for G2 being Subgraph of G1
for X, Y being set holds
( G2 .edgesBetween (X,Y) c= G1 .edgesBetween (X,Y) & G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y) )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for X, Y being set holds
( G2 .edgesBetween (X,Y) c= G1 .edgesBetween (X,Y) & G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y) )
let G2 be Subgraph of G1; ::_thesis: for X, Y being set holds
( G2 .edgesBetween (X,Y) c= G1 .edgesBetween (X,Y) & G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y) )
let X, Y be set ; ::_thesis: ( G2 .edgesBetween (X,Y) c= G1 .edgesBetween (X,Y) & G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y) )
now__::_thesis:_for_x_being_set_st_x_in_G2_.edgesBetween_(X,Y)_holds_
x_in_G1_.edgesBetween_(X,Y)
let x be set ; ::_thesis: ( x in G2 .edgesBetween (X,Y) implies x in G1 .edgesBetween (X,Y) )
assume  x in G2 .edgesBetween (X,Y) ; ::_thesis: x in G1 .edgesBetween (X,Y)
then  x SJoins X,Y,G2 by Def30;
then  x SJoins X,Y,G1 by Th72;
hence  x in G1 .edgesBetween (X,Y) by Def30; ::_thesis: verum
end;
hence  G2 .edgesBetween (X,Y) c= G1 .edgesBetween (X,Y) by TARSKI:def_3; ::_thesis: G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y)
now__::_thesis:_for_x_being_set_st_x_in_G2_.edgesDBetween_(X,Y)_holds_
x_in_G1_.edgesDBetween_(X,Y)
let x be set ; ::_thesis: ( x in G2 .edgesDBetween (X,Y) implies x in G1 .edgesDBetween (X,Y) )
assume  x in G2 .edgesDBetween (X,Y) ; ::_thesis: x in G1 .edgesDBetween (X,Y)
then  x DSJoins X,Y,G2 by Def31;
then  x DSJoins X,Y,G1 by Th72;
hence  x in G1 .edgesDBetween (X,Y) by Def31; ::_thesis: verum
end;
hence  G2 .edgesDBetween (X,Y) c= G1 .edgesDBetween (X,Y) by TARSKI:def_3; ::_thesis: verum
end;

theorem Th78: :: GLIB_000:78
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 implies ( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() ) )
assume A1: v1 = v2 ; ::_thesis: ( v2 .edgesIn() c= v1 .edgesIn() & v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
now__::_thesis:_for_x_being_set_st_x_in_v2_.edgesIn()_holds_
x_in_v1_.edgesIn()
let x be set ; ::_thesis: ( x in v2 .edgesIn() implies x in v1 .edgesIn() )
assume A2: x in v2 .edgesIn() ; ::_thesis: x in v1 .edgesIn()
then  (the_Target_of G2) . x = v2 by Lm8;
then A3: (the_Target_of G1) . x = v1 by A1, A2, Def32;
 x in the_Edges_of G2 by A2;
hence  x in v1 .edgesIn() by A3, Lm8; ::_thesis: verum
end;
hence  v2 .edgesIn() c= v1 .edgesIn() by TARSKI:def_3; ::_thesis: ( v2 .edgesOut() c= v1 .edgesOut() & v2 .edgesInOut() c= v1 .edgesInOut() )
now__::_thesis:_for_x_being_set_st_x_in_v2_.edgesOut()_holds_
x_in_v1_.edgesOut()
let x be set ; ::_thesis: ( x in v2 .edgesOut() implies x in v1 .edgesOut() )
assume A4: x in v2 .edgesOut() ; ::_thesis: x in v1 .edgesOut()
then  (the_Source_of G2) . x = v2 by Lm9;
then A5: (the_Source_of G1) . x = v1 by A1, A4, Def32;
 x in the_Edges_of G2 by A4;
hence  x in v1 .edgesOut() by A5, Lm9; ::_thesis: verum
end;
hence  v2 .edgesOut() c= v1 .edgesOut() by TARSKI:def_3; ::_thesis: v2 .edgesInOut() c= v1 .edgesInOut()
now__::_thesis:_for_x_being_set_st_x_in_v2_.edgesInOut()_holds_
x_in_v1_.edgesInOut()
let x be set ; ::_thesis: ( x in v2 .edgesInOut() implies x in v1 .edgesInOut() )
assume A6: x in v2 .edgesInOut() ; ::_thesis: x in v1 .edgesInOut()
then  ( (the_Source_of G2) . x = v2 or (the_Target_of G2) . x = v2 ) by Th61;
then A7: ( (the_Source_of G1) . x = v1 or (the_Target_of G1) . x = v1 ) by A1, A6, Def32;
 x in the_Edges_of G2 by A6;
hence  x in v1 .edgesInOut() by A7, Th61; ::_thesis: verum
end;
hence  v2 .edgesInOut() c= v1 .edgesInOut() by TARSKI:def_3; ::_thesis: verum
end;

theorem Th79: :: GLIB_000:79
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 holds
( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 implies ( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) ) )
assume A1: v1 = v2 ; ::_thesis: ( v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) & v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_v2_.edgesIn()_implies_x_in_(v1_.edgesIn())_/\_(the_Edges_of_G2)_)_&_(_x_in_(v1_.edgesIn())_/\_(the_Edges_of_G2)_implies_x_in_v2_.edgesIn()_)_)
let x be set ; ::_thesis: ( ( x in v2 .edgesIn() implies x in (v1 .edgesIn()) /\ (the_Edges_of G2) ) & ( x in (v1 .edgesIn()) /\ (the_Edges_of G2) implies x in v2 .edgesIn() ) )
hereby  ::_thesis: ( x in (v1 .edgesIn()) /\ (the_Edges_of G2) implies x in v2 .edgesIn() )
assume A2: x in v2 .edgesIn() ; ::_thesis: x in (v1 .edgesIn()) /\ (the_Edges_of G2)
 v2 .edgesIn() c= v1 .edgesIn() by A1, Th78;
hence  x in (v1 .edgesIn()) /\ (the_Edges_of G2) by A2, XBOOLE_0:def_4; ::_thesis: verum
end;
assume A3: x in (v1 .edgesIn()) /\ (the_Edges_of G2) ; ::_thesis: x in v2 .edgesIn()
then A4: x in the_Edges_of G2 by XBOOLE_0:def_4;
 x in v1 .edgesIn() by A3, XBOOLE_0:def_4;
then  (the_Target_of G1) . x = v1 by Lm8;
then  (the_Target_of G2) . x = v2 by A1, A4, Def32;
hence  x in v2 .edgesIn() by A4, Lm8; ::_thesis: verum
end;
hence A5: v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) by TARSKI:1; ::_thesis: ( v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) & v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) )
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_v2_.edgesOut()_implies_x_in_(v1_.edgesOut())_/\_(the_Edges_of_G2)_)_&_(_x_in_(v1_.edgesOut())_/\_(the_Edges_of_G2)_implies_x_in_v2_.edgesOut()_)_)
let x be set ; ::_thesis: ( ( x in v2 .edgesOut() implies x in (v1 .edgesOut()) /\ (the_Edges_of G2) ) & ( x in (v1 .edgesOut()) /\ (the_Edges_of G2) implies x in v2 .edgesOut() ) )
hereby  ::_thesis: ( x in (v1 .edgesOut()) /\ (the_Edges_of G2) implies x in v2 .edgesOut() )
assume A6: x in v2 .edgesOut() ; ::_thesis: x in (v1 .edgesOut()) /\ (the_Edges_of G2)
 v2 .edgesOut() c= v1 .edgesOut() by A1, Th78;
hence  x in (v1 .edgesOut()) /\ (the_Edges_of G2) by A6, XBOOLE_0:def_4; ::_thesis: verum
end;
assume A7: x in (v1 .edgesOut()) /\ (the_Edges_of G2) ; ::_thesis: x in v2 .edgesOut()
then A8: x in the_Edges_of G2 by XBOOLE_0:def_4;
 x in v1 .edgesOut() by A7, XBOOLE_0:def_4;
then  (the_Source_of G1) . x = v1 by Lm9;
then  (the_Source_of G2) . x = v2 by A1, A8, Def32;
hence  x in v2 .edgesOut() by A8, Lm9; ::_thesis: verum
end;
hence A9: v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) by TARSKI:1; ::_thesis: v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2)
now__::_thesis:_for_x_being_set_holds_
(_(_x_in_(v1_.edgesInOut())_/\_(the_Edges_of_G2)_implies_x_in_v2_.edgesInOut()_)_&_(_x_in_v2_.edgesInOut()_implies_x_in_(v1_.edgesInOut())_/\_(the_Edges_of_G2)_)_)
let x be set ; ::_thesis: ( ( x in (v1 .edgesInOut()) /\ (the_Edges_of G2) implies x in v2 .edgesInOut() ) & ( x in v2 .edgesInOut() implies x in (v1 .edgesInOut()) /\ (the_Edges_of G2) ) )
hereby  ::_thesis: ( x in v2 .edgesInOut() implies x in (v1 .edgesInOut()) /\ (the_Edges_of G2) )
assume A10: x in (v1 .edgesInOut()) /\ (the_Edges_of G2) ; ::_thesis: x in v2 .edgesInOut()
then A11: x in the_Edges_of G2 by XBOOLE_0:def_4;
A12: x in v1 .edgesInOut() by A10, XBOOLE_0:def_4;
now__::_thesis:_x_in_v2_.edgesInOut()
percases ( x in v1 .edgesIn() or x in v1 .edgesOut() ) by A12, XBOOLE_0:def_3;
suppose x in v1 .edgesIn() ; ::_thesis: x in v2 .edgesInOut()
then  x in (v1 .edgesIn()) /\ (the_Edges_of G2) by A11, XBOOLE_0:def_4;
hence  x in v2 .edgesInOut() by A5, XBOOLE_0:def_3; ::_thesis: verum
end;
suppose x in v1 .edgesOut() ; ::_thesis: x in v2 .edgesInOut()
then  x in (v1 .edgesOut()) /\ (the_Edges_of G2) by A11, XBOOLE_0:def_4;
hence  x in v2 .edgesInOut() by A9, XBOOLE_0:def_3; ::_thesis: verum
end;
end;
end;
hence  x in v2 .edgesInOut() ; ::_thesis: verum
end;
assume A13: x in v2 .edgesInOut() ; ::_thesis: x in (v1 .edgesInOut()) /\ (the_Edges_of G2)
now__::_thesis:_x_in_(v1_.edgesInOut())_/\_(the_Edges_of_G2)
percases ( x in (v1 .edgesIn()) /\ (the_Edges_of G2) or x in (v1 .edgesOut()) /\ (the_Edges_of G2) ) by A5, A9, A13, XBOOLE_0:def_3;
supposeA14: x in (v1 .edgesIn()) /\ (the_Edges_of G2) ; ::_thesis: x in (v1 .edgesInOut()) /\ (the_Edges_of G2)
then  x in v1 .edgesIn() by XBOOLE_0:def_4;
then A15: x in (v1 .edgesIn()) \/ (v1 .edgesOut()) by XBOOLE_0:def_3;
 x in the_Edges_of G2 by A14, XBOOLE_0:def_4;
hence  x in (v1 .edgesInOut()) /\ (the_Edges_of G2) by A15, XBOOLE_0:def_4; ::_thesis: verum
end;
supposeA16: x in (v1 .edgesOut()) /\ (the_Edges_of G2) ; ::_thesis: x in (v1 .edgesInOut()) /\ (the_Edges_of G2)
then  x in v1 .edgesOut() by XBOOLE_0:def_4;
then A17: x in (v1 .edgesIn()) \/ (v1 .edgesOut()) by XBOOLE_0:def_3;
 x in the_Edges_of G2 by A16, XBOOLE_0:def_4;
hence  x in (v1 .edgesInOut()) /\ (the_Edges_of G2) by A17, XBOOLE_0:def_4; ::_thesis: verum
end;
end;
end;
hence  x in (v1 .edgesInOut()) /\ (the_Edges_of G2) ; ::_thesis: verum
end;
hence  v2 .edgesInOut() = (v1 .edgesInOut()) /\ (the_Edges_of G2) by TARSKI:1; ::_thesis: verum
end;

theorem :: GLIB_000:80
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2
for e being set st v1 = v2 & e in the_Edges_of G2 holds
v1 .adj e = v2 .adj e
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2
for e being set st v1 = v2 & e in the_Edges_of G2 holds
v1 .adj e = v2 .adj e
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2
for e being set st v1 = v2 & e in the_Edges_of G2 holds
v1 .adj e = v2 .adj e
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2
for e being set st v1 = v2 & e in the_Edges_of G2 holds
v1 .adj e = v2 .adj e
let v2 be Vertex of G2; ::_thesis: for e being set st v1 = v2 & e in the_Edges_of G2 holds
v1 .adj e = v2 .adj e
let e be set ; ::_thesis: ( v1 = v2 & e in the_Edges_of G2 implies v1 .adj e = v2 .adj e )
assume that
A1: v1 = v2 and
A2: e in the_Edges_of G2 ; ::_thesis: v1 .adj e = v2 .adj e
A3: ( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) by A2, Def32;
now__::_thesis:_v1_.adj_e_=_v2_.adj_e
percases ( (the_Target_of G1) . e = v1 or ( (the_Source_of G1) . e = v1 & (the_Target_of G1) . e <> v1 ) or ( (the_Source_of G1) . e <> v1 & (the_Target_of G1) . e <> v1 ) ) ;
supposeA4: (the_Target_of G1) . e = v1 ; ::_thesis: v1 .adj e = v2 .adj e
hence v1 .adj e = (the_Source_of G1) . e by A2, Def41
.= v2 .adj e by A1, A2, A3, A4, Def41 ;
::_thesis: verum
end;
supposeA5: ( (the_Source_of G1) . e = v1 & (the_Target_of G1) . e <> v1 ) ; ::_thesis: v1 .adj e = v2 .adj e
hence v1 .adj e = (the_Target_of G1) . e by A2, Def41
.= v2 .adj e by A1, A2, A3, A5, Def41 ;
::_thesis: verum
end;
supposeA6: ( (the_Source_of G1) . e <> v1 & (the_Target_of G1) . e <> v1 ) ; ::_thesis: v1 .adj e = v2 .adj e
hence v1 .adj e = v2 by A1, Def41
.= v2 .adj e by A1, A3, A6, Def41 ;
::_thesis: verum
end;
end;
end;
hence  v1 .adj e = v2 .adj e ; ::_thesis: verum
end;

theorem :: GLIB_000:81
for G1 being finite _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
proof
let G1 be finite _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 implies ( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() ) )
assume A1: v1 = v2 ; ::_thesis: ( v2 .inDegree() <= v1 .inDegree() & v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
then  v2 .edgesIn() = (v1 .edgesIn()) /\ (the_Edges_of G2) by Th79;
hence A2: v2 .inDegree() <= v1 .inDegree() by NAT_1:43, XBOOLE_1:17; ::_thesis: ( v2 .outDegree() <= v1 .outDegree() & v2 .degree() <= v1 .degree() )
A3: v2 .edgesOut() = (v1 .edgesOut()) /\ (the_Edges_of G2) by A1, Th79;
hence  v2 .outDegree() <= v1 .outDegree() by NAT_1:43, XBOOLE_1:17; ::_thesis: v2 .degree() <= v1 .degree()
 v2 .outDegree() <= card (v1 .edgesOut()) by A3, NAT_1:43, XBOOLE_1:17;
hence  v2 .degree() <= v1 .degree() by A2, XREAL_1:7; ::_thesis: verum
end;

theorem :: GLIB_000:82
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 implies ( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() ) )
assume A1: v1 = v2 ; ::_thesis: ( v2 .inNeighbors() c= v1 .inNeighbors() & v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
now__::_thesis:_for_v_being_set_st_v_in_v2_.inNeighbors()_holds_
v_in_v1_.inNeighbors()
let v be set ; ::_thesis: ( v in v2 .inNeighbors() implies v in v1 .inNeighbors() )
assume  v in v2 .inNeighbors() ; ::_thesis: v in v1 .inNeighbors()
then consider e being set  such that
A2: e DJoins v,v2,G2 by Th69;
 e DJoins v,v1,G1 by A1, A2, Th72;
hence  v in v1 .inNeighbors() by Th69; ::_thesis: verum
end;
hence  v2 .inNeighbors() c= v1 .inNeighbors() by TARSKI:def_3; ::_thesis: ( v2 .outNeighbors() c= v1 .outNeighbors() & v2 .allNeighbors() c= v1 .allNeighbors() )
now__::_thesis:_for_v_being_set_st_v_in_v2_.outNeighbors()_holds_
v_in_v1_.outNeighbors()
let v be set ; ::_thesis: ( v in v2 .outNeighbors() implies v in v1 .outNeighbors() )
assume  v in v2 .outNeighbors() ; ::_thesis: v in v1 .outNeighbors()
then consider e being set  such that
A3: e DJoins v2,v,G2 by Th70;
 e DJoins v1,v,G1 by A1, A3, Th72;
hence  v in v1 .outNeighbors() by Th70; ::_thesis: verum
end;
hence  v2 .outNeighbors() c= v1 .outNeighbors() by TARSKI:def_3; ::_thesis: v2 .allNeighbors() c= v1 .allNeighbors()
now__::_thesis:_for_v_being_set_st_v_in_v2_.allNeighbors()_holds_
v_in_v1_.allNeighbors()
let v be set ; ::_thesis: ( v in v2 .allNeighbors() implies v in v1 .allNeighbors() )
assume  v in v2 .allNeighbors() ; ::_thesis: v in v1 .allNeighbors()
then consider e being set  such that
A4: e Joins v2,v,G2 by Th71;
 e Joins v1,v,G1 by A1, A4, Lm5;
hence  v in v1 .allNeighbors() by Th71; ::_thesis: verum
end;
hence  v2 .allNeighbors() c= v1 .allNeighbors() by TARSKI:def_3; ::_thesis: verum
end;

theorem :: GLIB_000:83
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is isolated holds
v2 is isolated
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is isolated holds
v2 is isolated
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is isolated holds
v2 is isolated
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 & v1 is isolated holds
v2 is isolated
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 & v1 is isolated implies v2 is isolated )
assume  ( v1 = v2 & v1 is isolated ) ; ::_thesis: v2 is isolated
then  ( v1 .edgesInOut() = {} & v2 .edgesInOut() c= v1 .edgesInOut() ) by Def49, Th78;
then  v2 .edgesInOut() = {} ;
hence  v2 is isolated by Def49; ::_thesis: verum
end;

theorem :: GLIB_000:84
for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is endvertex & not v2 is endvertex holds
v2 is isolated
proof
let G1 be _Graph; ::_thesis: for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is endvertex & not v2 is endvertex holds
v2 is isolated
let G2 be Subgraph of G1; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 is endvertex & not v2 is endvertex holds
v2 is isolated
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 & v1 is endvertex & not v2 is endvertex holds
v2 is isolated
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 & v1 is endvertex & not v2 is endvertex implies v2 is isolated )
assume that
A1: v1 = v2 and
A2: v1 is endvertex ; ::_thesis: ( v2 is endvertex or v2 is isolated )
consider e being set  such that
A3: v1 .edgesInOut() = {e} and
A4: not e Joins v1,v1,G1 by A2, Def51;
 v2 .edgesInOut() c= v1 .edgesInOut() by A1, Th78;
then A5: ( v2 .edgesInOut() = {} or v2 .edgesInOut() = {e} ) by A3, ZFMISC_1:33;
now__::_thesis:_(_not_v2_is_isolated_implies_v2_is_endvertex_)
assume A6: not v2 is isolated ; ::_thesis: v2 is endvertex
 not e Joins v2,v2,G2 by A1, A4, Lm5;
hence  v2 is endvertex by A5, A6, Def49, Def51; ::_thesis: verum
end;
hence  ( v2 is endvertex or v2 is isolated ) ; ::_thesis: verum
end;

theorem Th85: :: GLIB_000:85
for G1, G2, G3 being _Graph st G1 == G2 & G2 == G3 holds
G1 == G3
proof
let G1, G2, G3 be _Graph; ::_thesis: ( G1 == G2 & G2 == G3 implies G1 == G3 )
assume that
A1: G1 == G2 and
A2: G2 == G3 ; ::_thesis: G1 == G3
A3: ( the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) by A1, Def34;
A4: ( the_Source_of G2 = the_Source_of G3 & the_Target_of G2 = the_Target_of G3 ) by A2, Def34;
A5: ( the_Vertices_of G2 = the_Vertices_of G3 & the_Edges_of G2 = the_Edges_of G3 ) by A2, Def34;
 ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 ) by A1, Def34;
hence  G1 == G3 by A3, A5, A4, Def34; ::_thesis: verum
end;

theorem Th86: :: GLIB_000:86
for G being _Graph
for G1, G2 being Subgraph of G st the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 holds
G1 == G2
proof
let G be _Graph; ::_thesis: for G1, G2 being Subgraph of G st the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 holds
G1 == G2
let G1, G2 be Subgraph of G; ::_thesis: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 implies G1 == G2 )
assume that
A1: the_Vertices_of G1 = the_Vertices_of G2 and
A2: the_Edges_of G1 = the_Edges_of G2 ; ::_thesis: G1 == G2
A3: ( dom (the_Target_of G1) = the_Edges_of G1 & dom (the_Target_of G2) = the_Edges_of G2 ) by FUNCT_2:def_1;
now__::_thesis:_for_e_being_set_st_e_in_the_Edges_of_G1_holds_
(the_Target_of_G1)_._e_=_(the_Target_of_G2)_._e
let e be set ; ::_thesis: ( e in the_Edges_of G1 implies (the_Target_of G1) . e = (the_Target_of G2) . e )
assume A4: e in the_Edges_of G1 ; ::_thesis: (the_Target_of G1) . e = (the_Target_of G2) . e
then  (the_Target_of G1) . e = (the_Target_of G) . e by Def32;
hence  (the_Target_of G1) . e = (the_Target_of G2) . e by A2, A4, Def32; ::_thesis: verum
end;
then A5: the_Target_of G1 = the_Target_of G2 by A2, A3, FUNCT_1:2;
A6: now__::_thesis:_for_e_being_set_st_e_in_the_Edges_of_G1_holds_
(the_Source_of_G1)_._e_=_(the_Source_of_G2)_._e
let e be set ; ::_thesis: ( e in the_Edges_of G1 implies (the_Source_of G1) . e = (the_Source_of G2) . e )
assume A7: e in the_Edges_of G1 ; ::_thesis: (the_Source_of G1) . e = (the_Source_of G2) . e
then  (the_Source_of G1) . e = (the_Source_of G) . e by Def32;
hence  (the_Source_of G1) . e = (the_Source_of G2) . e by A2, A7, Def32; ::_thesis: verum
end;
 ( dom (the_Source_of G1) = the_Edges_of G1 & dom (the_Source_of G2) = the_Edges_of G2 ) by FUNCT_2:def_1;
then  the_Source_of G1 = the_Source_of G2 by A2, A6, FUNCT_1:2;
hence  G1 == G2 by A1, A2, A5, Def34; ::_thesis: verum
end;

theorem Th87: :: GLIB_000:87
for G1, G2 being _Graph holds
( G1 == G2 iff ( G1 is Subgraph of G2 & G2 is Subgraph of G1 ) )
proof
let G1, G2 be _Graph; ::_thesis: ( G1 == G2 iff ( G1 is Subgraph of G2 & G2 is Subgraph of G1 ) )
 ( G1 is Subgraph of G2 & G2 is Subgraph of G1 iff ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 & the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) ) by Th41;
hence  ( G1 == G2 iff ( G1 is Subgraph of G2 & G2 is Subgraph of G1 ) ) by Def34; ::_thesis: verum
end;

theorem Th88: :: GLIB_000:88
for G1, G2 being _Graph
for e, x, y, X, Y being set st G1 == G2 holds
( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins X,Y,G1 implies e SJoins X,Y,G2 ) & ( e DSJoins X,Y,G1 implies e DSJoins X,Y,G2 ) )
proof
let G1, G2 be _Graph; ::_thesis: for e, x, y, X, Y being set st G1 == G2 holds
( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins X,Y,G1 implies e SJoins X,Y,G2 ) & ( e DSJoins X,Y,G1 implies e DSJoins X,Y,G2 ) )
let e, x, y, X, Y be set ; ::_thesis: ( G1 == G2 implies ( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins X,Y,G1 implies e SJoins X,Y,G2 ) & ( e DSJoins X,Y,G1 implies e DSJoins X,Y,G2 ) ) )
assume  G1 == G2 ; ::_thesis: ( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins X,Y,G1 implies e SJoins X,Y,G2 ) & ( e DSJoins X,Y,G1 implies e DSJoins X,Y,G2 ) )
then  G1 is Subgraph of G2 by Th87;
hence  ( ( e Joins x,y,G1 implies e Joins x,y,G2 ) & ( e DJoins x,y,G1 implies e DJoins x,y,G2 ) & ( e SJoins X,Y,G1 implies e SJoins X,Y,G2 ) & ( e DSJoins X,Y,G1 implies e DSJoins X,Y,G2 ) ) by Th72; ::_thesis: verum
end;

theorem :: GLIB_000:89
for G1, G2 being _Graph st G1 == G2 holds
( ( G1 is finite implies G2 is finite ) & ( G1 is loopless implies G2 is loopless ) & ( G1 is trivial implies G2 is trivial ) & ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
proof
let G1, G2 be _Graph; ::_thesis: ( G1 == G2 implies ( ( G1 is finite implies G2 is finite ) & ( G1 is loopless implies G2 is loopless ) & ( G1 is trivial implies G2 is trivial ) & ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) ) )
assume A1: G1 == G2 ; ::_thesis: ( ( G1 is finite implies G2 is finite ) & ( G1 is loopless implies G2 is loopless ) & ( G1 is trivial implies G2 is trivial ) & ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
then A2: the_Edges_of G1 = the_Edges_of G2 by Def34;
A3: the_Vertices_of G1 = the_Vertices_of G2 by A1, Def34;
hence  ( G1 is finite implies G2 is finite ) by A2, Def17; ::_thesis: ( ( G1 is loopless implies G2 is loopless ) & ( G1 is trivial implies G2 is trivial ) & ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
A4: ( the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) by A1, Def34;
A5: now__::_thesis:_(_G1_is_loopless_implies_G2_is_loopless_)
assume  G1 is loopless ; ::_thesis: G2 is loopless
then  for e being set holds
( not e in the_Edges_of G2 or not (the_Source_of G2) . e = (the_Target_of G2) . e ) by A2, A4, Def18;
hence  G2 is loopless by Def18; ::_thesis: verum
end;
hence  ( G1 is loopless implies G2 is loopless ) ; ::_thesis: ( ( G1 is trivial implies G2 is trivial ) & ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
hereby  ::_thesis: ( ( G1 is non-multi implies G2 is non-multi ) & ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
assume  G1 is trivial ; ::_thesis: G2 is trivial
then  card (the_Vertices_of G2) = 1 by A3, Def19;
hence  G2 is trivial by Def19; ::_thesis: verum
end;
A6: now__::_thesis:_(_G1_is_non-multi_implies_G2_is_non-multi_)
assume A7: G1 is non-multi ; ::_thesis: G2 is non-multi
now__::_thesis:_for_e1,_e2,_v1,_v2_being_set_st_e1_Joins_v1,v2,G2_&_e2_Joins_v1,v2,G2_holds_
e1_=_e2
let e1, e2, v1, v2 be set ; ::_thesis: ( e1 Joins v1,v2,G2 & e2 Joins v1,v2,G2 implies e1 = e2 )
assume  ( e1 Joins v1,v2,G2 & e2 Joins v1,v2,G2 ) ; ::_thesis: e1 = e2
then  ( e1 Joins v1,v2,G1 & e2 Joins v1,v2,G1 ) by A1, Th88;
hence  e1 = e2 by A7, Def20; ::_thesis: verum
end;
hence  G2 is non-multi by Def20; ::_thesis: verum
end;
hence  ( G1 is non-multi implies G2 is non-multi ) ; ::_thesis: ( ( G1 is non-Dmulti implies G2 is non-Dmulti ) & ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
A8: now__::_thesis:_(_G1_is_non-Dmulti_implies_G2_is_non-Dmulti_)
assume A9: G1 is non-Dmulti ; ::_thesis: G2 is non-Dmulti
now__::_thesis:_for_e1,_e2,_v1,_v2_being_set_st_e1_DJoins_v1,v2,G2_&_e2_DJoins_v1,v2,G2_holds_
e1_=_e2
let e1, e2, v1, v2 be set ; ::_thesis: ( e1 DJoins v1,v2,G2 & e2 DJoins v1,v2,G2 implies e1 = e2 )
assume  ( e1 DJoins v1,v2,G2 & e2 DJoins v1,v2,G2 ) ; ::_thesis: e1 = e2
then  ( e1 DJoins v1,v2,G1 & e2 DJoins v1,v2,G1 ) by A1, Th88;
hence  e1 = e2 by A9, Def21; ::_thesis: verum
end;
hence  G2 is non-Dmulti by Def21; ::_thesis: verum
end;
hence  ( G1 is non-Dmulti implies G2 is non-Dmulti ) ; ::_thesis: ( ( G1 is simple implies G2 is simple ) & ( G1 is Dsimple implies G2 is Dsimple ) )
thus  ( G1 is simple implies G2 is simple ) by A5, A6; ::_thesis: ( G1 is Dsimple implies G2 is Dsimple )
thus  ( G1 is Dsimple implies G2 is Dsimple ) by A5, A8; ::_thesis: verum
end;

theorem Th90: :: GLIB_000:90
for G1, G2 being _Graph
for X, Y being set st G1 == G2 holds
( G1 .order() = G2 .order() & G1 .size() = G2 .size() & G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
proof
let G1, G2 be _Graph; ::_thesis: for X, Y being set st G1 == G2 holds
( G1 .order() = G2 .order() & G1 .size() = G2 .size() & G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
let X, Y be set ; ::_thesis: ( G1 == G2 implies ( G1 .order() = G2 .order() & G1 .size() = G2 .size() & G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) ) )
assume A1: G1 == G2 ; ::_thesis: ( G1 .order() = G2 .order() & G1 .size() = G2 .size() & G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
hence  G1 .order() = G2 .order() by Def34; ::_thesis: ( G1 .size() = G2 .size() & G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
thus  G1 .size() = G2 .size() by A1, Def34; ::_thesis: ( G1 .edgesInto X = G2 .edgesInto X & G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
A2: the_Edges_of G1 = the_Edges_of G2 by A1, Def34;
A3: the_Target_of G1 = the_Target_of G2 by A1, Def34;
A4: now__::_thesis:_for_e_being_set_holds_
(_e_in_G1_.edgesInto_X_iff_e_in_G2_.edgesInto_X_)
let e be set ; ::_thesis: ( e in G1 .edgesInto X iff e in G2 .edgesInto X )
 ( e in G1 .edgesInto X iff ( e in the_Edges_of G2 & (the_Target_of G2) . e in X ) ) by A2, A3, Def26;
hence  ( e in G1 .edgesInto X iff e in G2 .edgesInto X ) by Def26; ::_thesis: verum
end;
hence A5: G1 .edgesInto X = G2 .edgesInto X by TARSKI:1; ::_thesis: ( G1 .edgesOutOf X = G2 .edgesOutOf X & G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
A6: the_Source_of G1 = the_Source_of G2 by A1, Def34;
A7: now__::_thesis:_for_e_being_set_holds_
(_e_in_G1_.edgesOutOf_X_iff_e_in_G2_.edgesOutOf_X_)
let e be set ; ::_thesis: ( e in G1 .edgesOutOf X iff e in G2 .edgesOutOf X )
 ( e in G1 .edgesOutOf X iff ( e in the_Edges_of G2 & (the_Source_of G2) . e in X ) ) by A2, A6, Def27;
hence  ( e in G1 .edgesOutOf X iff e in G2 .edgesOutOf X ) by Def27; ::_thesis: verum
end;
hence A8: G1 .edgesOutOf X = G2 .edgesOutOf X by TARSKI:1; ::_thesis: ( G1 .edgesInOut X = G2 .edgesInOut X & G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
thus  G1 .edgesInOut X = G2 .edgesInOut X by A5, A7, TARSKI:1; ::_thesis: ( G1 .edgesBetween X = G2 .edgesBetween X & G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) )
thus  G1 .edgesBetween X = G2 .edgesBetween X by A4, A8, TARSKI:1; ::_thesis: G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y)
now__::_thesis:_for_e_being_set_holds_
(_e_in_G2_.edgesDBetween_(X,Y)_iff_e_in_G1_.edgesDBetween_(X,Y)_)
let e be set ; ::_thesis: ( e in G2 .edgesDBetween (X,Y) iff e in G1 .edgesDBetween (X,Y) )
 ( e in G1 .edgesDBetween (X,Y) iff e DSJoins X,Y,G1 ) by Def31;
then  ( e in G1 .edgesDBetween (X,Y) iff e DSJoins X,Y,G2 ) by A1, Th88;
hence  ( e in G2 .edgesDBetween (X,Y) iff e in G1 .edgesDBetween (X,Y) ) by Def31; ::_thesis: verum
end;
hence  G1 .edgesDBetween (X,Y) = G2 .edgesDBetween (X,Y) by TARSKI:1; ::_thesis: verum
end;

theorem Th91: :: GLIB_000:91
for G1, G2, G3 being _Graph st G1 == G2 & G3 is Subgraph of G1 holds
G3 is Subgraph of G2
proof
let G1, G2, G3 be _Graph; ::_thesis: ( G1 == G2 & G3 is Subgraph of G1 implies G3 is Subgraph of G2 )
assume that
A1: G1 == G2 and
A2: G3 is Subgraph of G1 ; ::_thesis: G3 is Subgraph of G2
 the_Vertices_of G3 c= the_Vertices_of G1 by A2, Def32;
hence  the_Vertices_of G3 c= the_Vertices_of G2 by A1, Def34; :: according to GLIB_000:def_32 ::_thesis: ( the_Edges_of G3 c= the_Edges_of G2 & ( for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of G2) . e & (the_Target_of G3) . e = (the_Target_of G2) . e ) ) )
 the_Edges_of G3 c= the_Edges_of G1 by A2, Def32;
hence  the_Edges_of G3 c= the_Edges_of G2 by A1, Def34; ::_thesis: for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of G2) . e & (the_Target_of G3) . e = (the_Target_of G2) . e )
let e be set ; ::_thesis: ( e in the_Edges_of G3 implies ( (the_Source_of G3) . e = (the_Source_of G2) . e & (the_Target_of G3) . e = (the_Target_of G2) . e ) )
assume A3: e in the_Edges_of G3 ; ::_thesis: ( (the_Source_of G3) . e = (the_Source_of G2) . e & (the_Target_of G3) . e = (the_Target_of G2) . e )
hence (the_Source_of G3) . e = (the_Source_of G1) . e by A2, Def32
.= (the_Source_of G2) . e by A1, Def34 ;
::_thesis: (the_Target_of G3) . e = (the_Target_of G2) . e
thus (the_Target_of G3) . e = (the_Target_of G1) . e by A2, A3, Def32
.= (the_Target_of G2) . e by A1, Def34 ; ::_thesis: verum
end;

theorem :: GLIB_000:92
for G1, G2, G3 being _Graph st G1 == G2 & G1 is Subgraph of G3 holds
G2 is Subgraph of G3
proof
let G1, G2, G3 be _Graph; ::_thesis: ( G1 == G2 & G1 is Subgraph of G3 implies G2 is Subgraph of G3 )
assume that
A1: G1 == G2 and
A2: G1 is Subgraph of G3 ; ::_thesis: G2 is Subgraph of G3
A3: the_Edges_of G1 = the_Edges_of G2 by A1, Def34;
A4: ( the_Source_of G1 = the_Source_of G2 & the_Target_of G1 = the_Target_of G2 ) by A1, Def34;
 the_Vertices_of G1 = the_Vertices_of G2 by A1, Def34;
hence  ( the_Vertices_of G2 c= the_Vertices_of G3 & the_Edges_of G2 c= the_Edges_of G3 ) by A2, A3, Def32; :: according to GLIB_000:def_32 ::_thesis: for e being set st e in the_Edges_of G2 holds
( (the_Source_of G2) . e = (the_Source_of G3) . e & (the_Target_of G2) . e = (the_Target_of G3) . e )
let e be set ; ::_thesis: ( e in the_Edges_of G2 implies ( (the_Source_of G2) . e = (the_Source_of G3) . e & (the_Target_of G2) . e = (the_Target_of G3) . e ) )
assume  e in the_Edges_of G2 ; ::_thesis: ( (the_Source_of G2) . e = (the_Source_of G3) . e & (the_Target_of G2) . e = (the_Target_of G3) . e )
hence  ( (the_Source_of G2) . e = (the_Source_of G3) . e & (the_Target_of G2) . e = (the_Target_of G3) . e ) by A2, A3, A4, Def32; ::_thesis: verum
end;

theorem :: GLIB_000:93
for G being _Graph
for V, E being set
for G1, G2 being inducedSubgraph of G,V,E holds G1 == G2
proof
let G be _Graph; ::_thesis: for V, E being set
for G1, G2 being inducedSubgraph of G,V,E holds G1 == G2
let V, E be set ; ::_thesis: for G1, G2 being inducedSubgraph of G,V,E holds G1 == G2
let G1, G2 be inducedSubgraph of G,V,E; ::_thesis: G1 == G2
now__::_thesis:_G1_==_G2
percases ( ( V is non empty Subset of (the_Vertices_of G) & E c= G .edgesBetween V ) or not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) ;
supposeA1: ( V is non empty Subset of (the_Vertices_of G) & E c= G .edgesBetween V ) ; ::_thesis: G1 == G2
then A2: ( the_Edges_of G1 = E & the_Edges_of G2 = E ) by Def37;
 ( the_Vertices_of G1 = V & the_Vertices_of G2 = V ) by A1, Def37;
hence  G1 == G2 by A2, Th86; ::_thesis: verum
end;
suppose ( not V is non empty Subset of (the_Vertices_of G) or not E c= G .edgesBetween V ) ; ::_thesis: G1 == G2
then  ( G1 == G & G2 == G ) by Def37;
hence  G1 == G2 by Th85; ::_thesis: verum
end;
end;
end;
hence  G1 == G2 ; ::_thesis: verum
end;

theorem :: GLIB_000:94
for G1 being _Graph
for G2 being inducedSubgraph of G1,(the_Vertices_of G1) holds G1 == G2
proof
let G1 be _Graph; ::_thesis: for G2 being inducedSubgraph of G1,(the_Vertices_of G1) holds G1 == G2
let G2 be inducedSubgraph of G1,(the_Vertices_of G1); ::_thesis: G1 == G2
A1: the_Vertices_of G1 c= the_Vertices_of G1 ;
then  the_Edges_of G2 = G1 .edgesBetween (the_Vertices_of G1) by Def37;
then A2: the_Edges_of G2 = the_Edges_of G1 by Th34;
then  the_Source_of G2 = (the_Source_of G1) | (the_Edges_of G1) by Th45;
then  the_Source_of G2 = (the_Source_of G1) | (dom (the_Source_of G1)) ;
then A3: the_Source_of G2 = the_Source_of G1 ;
 the_Target_of G2 = (the_Target_of G1) | (the_Edges_of G1) by A2, Th45;
then  the_Target_of G2 = (the_Target_of G1) | (dom (the_Target_of G1)) ;
then A4: the_Target_of G2 = the_Target_of G1 ;
 the_Vertices_of G2 = the_Vertices_of G1 by A1, Def37;
hence  G1 == G2 by A2, A3, A4, Def34; ::_thesis: verum
end;

theorem :: GLIB_000:95
for G1, G2 being _Graph
for V, E being set
for G3 being inducedSubgraph of G1,V,E st G1 == G2 holds
G3 is inducedSubgraph of G2,V,E
proof
let G1, G2 be _Graph; ::_thesis: for V, E being set
for G3 being inducedSubgraph of G1,V,E st G1 == G2 holds
G3 is inducedSubgraph of G2,V,E
let V, E be set ; ::_thesis: for G3 being inducedSubgraph of G1,V,E st G1 == G2 holds
G3 is inducedSubgraph of G2,V,E
let G3 be inducedSubgraph of G1,V,E; ::_thesis: ( G1 == G2 implies G3 is inducedSubgraph of G2,V,E )
assume A1: G1 == G2 ; ::_thesis: G3 is inducedSubgraph of G2,V,E
now__::_thesis:_G3_is_inducedSubgraph_of_G2,V,E
percases ( ( V is non empty Subset of (the_Vertices_of G1) & E c= G1 .edgesBetween V ) or not V is non empty Subset of (the_Vertices_of G1) or not E c= G1 .edgesBetween V ) ;
supposeA2: ( V is non empty Subset of (the_Vertices_of G1) & E c= G1 .edgesBetween V ) ; ::_thesis: G3 is inducedSubgraph of G2,V,E
then A3: ( the_Vertices_of G3 = V & the_Edges_of G3 = E ) by Def37;
A4: G3 is Subgraph of G2 by A1, Th91;
 ( V is non empty Subset of (the_Vertices_of G2) & E c= G2 .edgesBetween V ) by A1, A2, Def34, Th90;
hence  G3 is inducedSubgraph of G2,V,E by A3, A4, Def37; ::_thesis: verum
end;
supposeA5: ( not V is non empty Subset of (the_Vertices_of G1) or not E c= G1 .edgesBetween V ) ; ::_thesis: G3 is inducedSubgraph of G2,V,E
then A6: ( not V is non empty Subset of (the_Vertices_of G2) or not E c= G2 .edgesBetween V ) by A1, Def34, Th90;
 G3 == G1 by A5, Def37;
then A7: G3 == G2 by A1, Th85;
then  G3 is Subgraph of G2 by Th87;
hence  G3 is inducedSubgraph of G2,V,E by A6, A7, Def37; ::_thesis: verum
end;
end;
end;
hence  G3 is inducedSubgraph of G2,V,E ; ::_thesis: verum
end;

theorem Th96: :: GLIB_000:96
for G1, G2 being _Graph
for e being set
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
proof
let G1, G2 be _Graph; ::_thesis: for e being set
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
let e be set ; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 & G1 == G2 implies ( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() ) )
assume that
A1: v1 = v2 and
A2: G1 == G2 ; ::_thesis: ( v1 .edgesIn() = v2 .edgesIn() & v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus A3: v1 .edgesIn() = v2 .edgesIn() by A1, A2, Th90; ::_thesis: ( v1 .edgesOut() = v2 .edgesOut() & v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus A4: v1 .edgesOut() = v2 .edgesOut() by A1, A2, Th90; ::_thesis: ( v1 .edgesInOut() = v2 .edgesInOut() & v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus  v1 .edgesInOut() = v2 .edgesInOut() by A1, A2, Th90; ::_thesis: ( v1 .adj e = v2 .adj e & v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
now__::_thesis:_v1_.adj_e_=_v2_.adj_e
percases ( ( e in the_Edges_of G1 & (the_Target_of G1) . e = v1 ) or ( e in the_Edges_of G1 & (the_Source_of G1) . e = v1 & not (the_Target_of G1) . e = v1 ) or ( ( not e in the_Edges_of G1 or not (the_Target_of G1) . e = v1 ) & ( not e in the_Edges_of G1 or not (the_Source_of G1) . e = v1 or (the_Target_of G1) . e = v1 ) ) ) ;
supposeA5: ( e in the_Edges_of G1 & (the_Target_of G1) . e = v1 ) ; ::_thesis: v1 .adj e = v2 .adj e
then A6: ( e in the_Edges_of G2 & (the_Target_of G2) . e = v2 ) by A1, A2, Def34;
thus v1 .adj e = (the_Source_of G1) . e by A5, Def41
.= (the_Source_of G2) . e by A2, Def34
.= v2 .adj e by A6, Def41 ; ::_thesis: verum
end;
supposeA7: ( e in the_Edges_of G1 & (the_Source_of G1) . e = v1 & not (the_Target_of G1) . e = v1 ) ; ::_thesis: v1 .adj e = v2 .adj e
then A8: not (the_Target_of G2) . e = v2 by A1, A2, Def34;
A9: ( e in the_Edges_of G2 & (the_Source_of G2) . e = v2 ) by A1, A2, A7, Def34;
thus v1 .adj e = (the_Target_of G1) . e by A7, Def41
.= (the_Target_of G2) . e by A2, Def34
.= v2 .adj e by A9, A8, Def41 ; ::_thesis: verum
end;
supposeA10: ( ( not e in the_Edges_of G1 or not (the_Target_of G1) . e = v1 ) & ( not e in the_Edges_of G1 or not (the_Source_of G1) . e = v1 or (the_Target_of G1) . e = v1 ) ) ; ::_thesis: v1 .adj e = v2 .adj e
then A11: ( ( not e in the_Edges_of G2 or not (the_Target_of G2) . e = v2 ) & ( not e in the_Edges_of G2 or not (the_Source_of G2) . e = v2 or (the_Target_of G2) . e = v2 ) ) by A1, A2, Def34;
thus v1 .adj e = v2 by A1, A10, Def41
.= v2 .adj e by A11, Def41 ; ::_thesis: verum
end;
end;
end;
hence  v1 .adj e = v2 .adj e ; ::_thesis: ( v1 .inDegree() = v2 .inDegree() & v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus  v1 .inDegree() = v2 .inDegree() by A1, A2, Th90; ::_thesis: ( v1 .outDegree() = v2 .outDegree() & v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus  v1 .outDegree() = v2 .outDegree() by A1, A2, Th90; ::_thesis: ( v1 .degree() = v2 .degree() & v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
hence  v1 .degree() = v2 .degree() by A1, A2, Th90; ::_thesis: ( v1 .inNeighbors() = v2 .inNeighbors() & v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus  v1 .inNeighbors() = v2 .inNeighbors() by A2, A3, Def34; ::_thesis: ( v1 .outNeighbors() = v2 .outNeighbors() & v1 .allNeighbors() = v2 .allNeighbors() )
thus  v1 .outNeighbors() = v2 .outNeighbors() by A2, A4, Def34; ::_thesis: v1 .allNeighbors() = v2 .allNeighbors()
hence  v1 .allNeighbors() = v2 .allNeighbors() by A2, A3, Def34; ::_thesis: verum
end;

theorem :: GLIB_000:97
for G1, G2 being _Graph
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( ( v1 is isolated implies v2 is isolated ) & ( v1 is endvertex implies v2 is endvertex ) )
proof
let G1, G2 be _Graph; ::_thesis: for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( ( v1 is isolated implies v2 is isolated ) & ( v1 is endvertex implies v2 is endvertex ) )
let v1 be Vertex of G1; ::_thesis: for v2 being Vertex of G2 st v1 = v2 & G1 == G2 holds
( ( v1 is isolated implies v2 is isolated ) & ( v1 is endvertex implies v2 is endvertex ) )
let v2 be Vertex of G2; ::_thesis: ( v1 = v2 & G1 == G2 implies ( ( v1 is isolated implies v2 is isolated ) & ( v1 is endvertex implies v2 is endvertex ) ) )
assume A1: ( v1 = v2 & G1 == G2 ) ; ::_thesis: ( ( v1 is isolated implies v2 is isolated ) & ( v1 is endvertex implies v2 is endvertex ) )
hereby  ::_thesis: ( v1 is endvertex implies v2 is endvertex )
assume  v1 is isolated ; ::_thesis: v2 is isolated
then  v1 .edgesInOut() = {} by Def49;
then  v2 .edgesInOut() = {} by A1, Th96;
hence  v2 is isolated by Def49; ::_thesis: verum
end;
assume  v1 is endvertex ; ::_thesis: v2 is endvertex
then consider e being set  such that
A2: ( v1 .edgesInOut() = {e} & not e Joins v1,v1,G1 ) by Def51;
 ( v2 .edgesInOut() = {e} & not e Joins v2,v2,G2 ) by A1, A2, Th88, Th96;
hence  v2 is endvertex by Def51; ::_thesis: verum
end;

theorem Th98: :: GLIB_000:98
for G being _Graph
for G1, G2 being Subgraph of G holds
( not G1 c< G2 or the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
proof
let G be _Graph; ::_thesis: for G1, G2 being Subgraph of G holds
( not G1 c< G2 or the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
let G1, G2 be Subgraph of G; ::_thesis: ( not G1 c< G2 or the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
assume A1: G1 c< G2 ; ::_thesis: ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
then  G1 c= G2 by Def36;
then A2: G1 is Subgraph of G2 by Def35;
then A3: the_Vertices_of G1 c= the_Vertices_of G2 by Def32;
A4: the_Edges_of G1 c= the_Edges_of G2 by A2, Def32;
A5: not G1 == G2 by A1, Def36;
now__::_thesis:_(_the_Vertices_of_G1_c<_the_Vertices_of_G2_or_the_Edges_of_G1_c<_the_Edges_of_G2_)
percases ( the_Vertices_of G1 <> the_Vertices_of G2 or the_Edges_of G1 <> the_Edges_of G2 ) by A5, Th86;
suppose the_Vertices_of G1 <> the_Vertices_of G2 ; ::_thesis: ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
hence  ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 ) by A3, XBOOLE_0:def_8; ::_thesis: verum
end;
suppose the_Edges_of G1 <> the_Edges_of G2 ; ::_thesis: ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 )
hence  ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 ) by A4, XBOOLE_0:def_8; ::_thesis: verum
end;
end;
end;
hence  ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 ) ; ::_thesis: verum
end;

theorem :: GLIB_000:99
for G being _Graph
for G1, G2 being Subgraph of G holds
( not G1 c< G2 or ex v being set st
( v in the_Vertices_of G2 & not v in the_Vertices_of G1 ) or ex e being set st
( e in the_Edges_of G2 & not e in the_Edges_of G1 ) )
proof
let G be _Graph; ::_thesis: for G1, G2 being Subgraph of G holds
( not G1 c< G2 or ex v being set st
( v in the_Vertices_of G2 & not v in the_Vertices_of G1 ) or ex e being set st
( e in the_Edges_of G2 & not e in the_Edges_of G1 ) )
let G1, G2 be Subgraph of G; ::_thesis: ( not G1 c< G2 or ex v being set st
( v in the_Vertices_of G2 & not v in the_Vertices_of G1 ) or ex e being set st
( e in the_Edges_of G2 & not e in the_Edges_of G1 ) )
assume  G1 c< G2 ; ::_thesis: ( ex v being set st
( v in the_Vertices_of G2 & not v in the_Vertices_of G1 ) or ex e being set st
( e in the_Edges_of G2 & not e in the_Edges_of G1 ) )
then  ( the_Vertices_of G1 c< the_Vertices_of G2 or the_Edges_of G1 c< the_Edges_of G2 ) by Th98;
hence  ( ex v being set st
( v in the_Vertices_of G2 & not v in the_Vertices_of G1 ) or ex e being set st
( e in the_Edges_of G2 & not e in the_Edges_of G1 ) ) by XBOOLE_0:6; ::_thesis: verum
end;