:: WAYBEL_3 semantic presentation

definition
let c1 be non empty reflexive RelStr ;
let c2, c3 be Element of c1;
pred c2 is_way_below c3 means :Def1: :: WAYBEL_3:def 1
for b1 being non empty directed Subset of a1 st a3 <= sup b1 holds
ex b2 being Element of a1 st
( b2 in b1 & a2 <= b2 );
end;

:: deftheorem Def1 defines is_way_below WAYBEL_3:def 1 :
for b1 being non empty reflexive RelStr
for b2, b3 being Element of b1 holds
( b2 is_way_below b3 iff for b4 being non empty directed Subset of b1 st b3 <= sup b4 holds
ex b5 being Element of b1 st
( b5 in b4 & b2 <= b5 ) );

notation
let c1 be non empty reflexive RelStr ;
let c2, c3 be Element of c1;
synonym c2 << c3 for c2 is_way_below c3;
synonym c3 >> c2 for c2 is_way_below c3;
end;

definition
let c1 be non empty reflexive RelStr ;
let c2 be Element of c1;
attr a2 is compact means :Def2: :: WAYBEL_3:def 2
a2 is_way_below a2;
end;

:: deftheorem Def2 defines compact WAYBEL_3:def 2 :
for b1 being non empty reflexive RelStr
for b2 being Element of b1 holds
( b2 is compact iff b2 is_way_below b2 );

notation
let c1 be non empty reflexive RelStr ;
let c2 be Element of c1;
synonym isolated_from_below c2 for compact c2;
end;

theorem Th1: :: WAYBEL_3:1
for b1 being non empty reflexive antisymmetric RelStr
for b2, b3 being Element of b1 st b2 << b3 holds
b2 <= b3
proof end;

theorem Th2: :: WAYBEL_3:2
for b1 being non empty reflexive transitive RelStr
for b2, b3, b4, b5 being Element of b1 st b2 <= b3 & b3 << b4 & b4 <= b5 holds
b2 << b5
proof end;

theorem Th3: :: WAYBEL_3:3
for b1 being non empty Poset st ( b1 is with_suprema or b1 is /\-complete ) holds
for b2, b3, b4 being Element of b1 st b2 << b4 & b3 << b4 holds
( ex_sup_of {b2,b3},b1 & b2 "\/" b3 << b4 )
proof end;

theorem Th4: :: WAYBEL_3:4
for b1 being non empty reflexive antisymmetric lower-bounded RelStr
for b2 being Element of b1 holds Bottom b1 << b2
proof end;

theorem Th5: :: WAYBEL_3:5
for b1 being non empty Poset
for b2, b3, b4 being Element of b1 st b2 << b3 & b3 << b4 holds
b2 << b4
proof end;

theorem Th6: :: WAYBEL_3:6
for b1 being non empty reflexive antisymmetric RelStr
for b2, b3 being Element of b1 st b2 << b3 & b2 >> b3 holds
b2 = b3
proof end;

definition
let c1 be non empty reflexive RelStr ;
let c2 be Element of c1;
E7: { b1 where B is Element of c1 : b1 << c2 } c= the carrier of c1
proof end;
func waybelow c2 -> Subset of a1 equals :: WAYBEL_3:def 3
{ b1 where B is Element of a1 : b1 << a2 } ;
correctness
coherence
{ b1 where B is Element of c1 : b1 << c2 } is Subset of c1
;
by E7;
E8: { b1 where B is Element of c1 : b1 >> c2 } c= the carrier of c1
proof end;
func wayabove c2 -> Subset of a1 equals :: WAYBEL_3:def 4
{ b1 where B is Element of a1 : b1 >> a2 } ;
correctness
coherence
{ b1 where B is Element of c1 : b1 >> c2 } is Subset of c1
;
by E8;
end;

:: deftheorem Def3 defines waybelow WAYBEL_3:def 3 :
for b1 being non empty reflexive RelStr
for b2 being Element of b1 holds waybelow b2 = { b3 where B is Element of b1 : b3 << b2 } ;

:: deftheorem Def4 defines wayabove WAYBEL_3:def 4 :
for b1 being non empty reflexive RelStr
for b2 being Element of b1 holds wayabove b2 = { b3 where B is Element of b1 : b3 >> b2 } ;

theorem Th7: :: WAYBEL_3:7
for b1 being non empty reflexive RelStr
for b2, b3 being Element of b1 holds
( b2 in waybelow b3 iff b2 << b3 )
proof end;

theorem Th8: :: WAYBEL_3:8
for b1 being non empty reflexive RelStr
for b2, b3 being Element of b1 holds
( b2 in wayabove b3 iff b2 >> b3 )
proof end;

theorem Th9: :: WAYBEL_3:9
for b1 being non empty reflexive antisymmetric RelStr
for b2 being Element of b1 holds b2 is_>=_than waybelow b2
proof end;

theorem Th10: :: WAYBEL_3:10
for b1 being non empty reflexive antisymmetric RelStr
for b2 being Element of b1 holds b2 is_<=_than wayabove b2
proof end;

theorem Th11: :: WAYBEL_3:11
for b1 being non empty reflexive antisymmetric RelStr
for b2 being Element of b1 holds
( waybelow b2 c= downarrow b2 & wayabove b2 c= uparrow b2 )
proof end;

theorem Th12: :: WAYBEL_3:12
for b1 being non empty reflexive transitive RelStr
for b2, b3 being Element of b1 st b2 <= b3 holds
( waybelow b2 c= waybelow b3 & wayabove b3 c= wayabove b2 )
proof end;

registration
let c1 be non empty reflexive antisymmetric lower-bounded RelStr ;
let c2 be Element of c1;
cluster waybelow a2 -> non empty ;
coherence
not waybelow c2 is empty
proof end;
end;

registration
let c1 be non empty reflexive transitive RelStr ;
let c2 be Element of c1;
cluster waybelow a2 -> lower ;
coherence
waybelow c2 is lower
proof end;
cluster wayabove a2 -> upper ;
coherence
wayabove c2 is upper
proof end;
end;

registration
let c1 be sup-Semilattice;
let c2 be Element of c1;
cluster waybelow a2 -> directed lower ;
coherence
waybelow c2 is directed
proof end;
end;

registration
let c1 be non empty /\-complete Poset;
let c2 be Element of c1;
cluster waybelow a2 -> non empty directed lower ;
coherence
waybelow c2 is directed
proof end;
end;

registration
let c1 be non empty connected RelStr ;
cluster -> directed filtered Element of K40(the carrier of a1);
coherence
for b1 being Subset of c1 holds
( b1 is directed & b1 is filtered )
proof end;
end;

registration
cluster non empty lower-bounded up-complete -> non empty complete RelStr ;
coherence
for b1 being non empty Chain st b1 is up-complete & b1 is lower-bounded holds
b1 is complete
proof end;
end;

registration
cluster non empty complete RelStr ;
existence
ex b1 being non empty Chain st b1 is complete
proof end;
end;

theorem Th13: :: WAYBEL_3:13
for b1 being non empty up-complete Chain
for b2, b3 being Element of b1 st b2 < b3 holds
b2 << b3
proof end;

theorem Th14: :: WAYBEL_3:14
for b1 being non empty reflexive antisymmetric RelStr
for b2, b3 being Element of b1 st not b2 is compact & b2 << b3 holds
b2 < b3
proof end;

theorem Th15: :: WAYBEL_3:15
for b1 being non empty reflexive antisymmetric lower-bounded RelStr holds Bottom b1 is compact
proof end;

theorem Th16: :: WAYBEL_3:16
for b1 being non empty up-complete Poset
for b2 being non empty finite directed Subset of b1 holds sup b2 in b2
proof end;

theorem Th17: :: WAYBEL_3:17
for b1 being non empty up-complete Poset st b1 is finite holds
for b2 being Element of b1 holds b2 is compact
proof end;

theorem Th18: :: WAYBEL_3:18
for b1 being complete LATTICE
for b2, b3 being Element of b1 st b2 << b3 holds
for b4 being Subset of b1 st b3 <= sup b4 holds
ex b5 being finite Subset of b1 st
( b5 c= b4 & b2 <= sup b5 )
proof end;

theorem Th19: :: WAYBEL_3:19
for b1 being complete LATTICE
for b2, b3 being Element of b1 st ( for b4 being Subset of b1 st b3 <= sup b4 holds
ex b5 being finite Subset of b1 st
( b5 c= b4 & b2 <= sup b5 ) ) holds
b2 << b3
proof end;

theorem Th20: :: WAYBEL_3:20
for b1 being non empty reflexive transitive RelStr
for b2, b3 being Element of b1 st b2 << b3 holds
for b4 being Ideal of b1 st b3 <= sup b4 holds
b2 in b4
proof end;

theorem Th21: :: WAYBEL_3:21
for b1 being non empty up-complete Poset
for b2, b3 being Element of b1 st ( for b4 being Ideal of b1 st b3 <= sup b4 holds
b2 in b4 ) holds
b2 << b3
proof end;

theorem Th22: :: WAYBEL_3:22
for b1 being lower-bounded LATTICE st b1 is meet-continuous holds
for b2, b3 being Element of b1 holds
( b2 << b3 iff for b4 being Ideal of b1 st b3 = sup b4 holds
b2 in b4 )
proof end;

theorem Th23: :: WAYBEL_3:23
for b1 being complete LATTICE holds
( ( for b2 being Element of b1 holds b2 is compact ) iff for b2 being non empty Subset of b1 ex b3 being Element of b1 st
( b3 in b2 & ( for b4 being Element of b1 st b4 in b2 holds
not b3 < b4 ) ) )
proof end;

definition
let c1 be non empty reflexive RelStr ;
attr a1 is satisfying_axiom_of_approximation means :Def5: :: WAYBEL_3:def 5
for b1 being Element of a1 holds b1 = sup (waybelow b1);
end;

:: deftheorem Def5 defines satisfying_axiom_of_approximation WAYBEL_3:def 5 :
for b1 being non empty reflexive RelStr holds
( b1 is satisfying_axiom_of_approximation iff for b2 being Element of b1 holds b2 = sup (waybelow b2) );

registration
cluster non empty trivial reflexive -> non empty reflexive satisfying_axiom_of_approximation RelStr ;
coherence
for b1 being non empty reflexive RelStr st b1 is trivial holds
b1 is satisfying_axiom_of_approximation
proof end;
end;

definition
let c1 be non empty reflexive RelStr ;
attr a1 is continuous means :Def6: :: WAYBEL_3:def 6
( ( for b1 being Element of a1 holds
( not waybelow b1 is empty & waybelow b1 is directed ) ) & a1 is up-complete & a1 is satisfying_axiom_of_approximation );
end;

:: deftheorem Def6 defines continuous WAYBEL_3:def 6 :
for b1 being non empty reflexive RelStr holds
( b1 is continuous iff ( ( for b2 being Element of b1 holds
( not waybelow b2 is empty & waybelow b2 is directed ) ) & b1 is up-complete & b1 is satisfying_axiom_of_approximation ) );

registration
cluster non empty reflexive continuous -> non empty reflexive up-complete satisfying_axiom_of_approximation RelStr ;
coherence
for b1 being non empty reflexive RelStr st b1 is continuous holds
( b1 is up-complete & b1 is satisfying_axiom_of_approximation )
by Def6;
cluster lower-bounded up-complete satisfying_axiom_of_approximation -> lower-bounded continuous RelStr ;
coherence
for b1 being lower-bounded sup-Semilattice st b1 is up-complete & b1 is satisfying_axiom_of_approximation holds
b1 is continuous
proof end;
end;

registration
cluster strict complete up-complete satisfying_axiom_of_approximation continuous RelStr ;
existence
ex b1 being LATTICE st
( b1 is continuous & b1 is complete & b1 is strict )
proof end;
end;

registration
let c1 be non empty reflexive continuous RelStr ;
let c2 be Element of c1;
cluster waybelow a2 -> non empty directed ;
coherence
( not waybelow c2 is empty & waybelow c2 is directed )
by Def6;
end;

theorem Th24: :: WAYBEL_3:24
for b1 being up-complete Semilattice st ( for b2 being Element of b1 holds
( not waybelow b2 is empty & waybelow b2 is directed ) ) holds
( b1 is satisfying_axiom_of_approximation iff for b2, b3 being Element of b1 st not b2 <= b3 holds
ex b4 being Element of b1 st
( b4 << b2 & not b4 <= b3 ) )
proof end;

theorem Th25: :: WAYBEL_3:25
for b1 being continuous LATTICE
for b2, b3 being Element of b1 holds
( b2 <= b3 iff waybelow b2 c= waybelow b3 )
proof end;

registration
cluster non empty complete -> non empty satisfying_axiom_of_approximation RelStr ;
coherence
for b1 being non empty Chain st b1 is complete holds
b1 is satisfying_axiom_of_approximation
proof end;
end;

theorem Th26: :: WAYBEL_3:26
for b1 being complete LATTICE st ( for b2 being Element of b1 holds b2 is compact ) holds
b1 is satisfying_axiom_of_approximation
proof end;

definition
let c1 be Relation;
attr a1 is non-Empty means :Def7: :: WAYBEL_3:def 7
for b1 being 1-sorted st b1 in rng a1 holds
not b1 is empty;
attr a1 is reflexive-yielding means :Def8: :: WAYBEL_3:def 8
for b1 being RelStr st b1 in rng a1 holds
b1 is reflexive;
end;

:: deftheorem Def7 defines non-Empty WAYBEL_3:def 7 :
for b1 being Relation holds
( b1 is non-Empty iff for b2 being 1-sorted st b2 in rng b1 holds
not b2 is empty );

:: deftheorem Def8 defines reflexive-yielding WAYBEL_3:def 8 :
for b1 being Relation holds
( b1 is reflexive-yielding iff for b2 being RelStr st b2 in rng b1 holds
b2 is reflexive );

registration
let c1 be set ;
cluster RelStr-yielding non-Empty reflexive-yielding ManySortedSet of a1;
existence
ex b1 being ManySortedSet of c1 st
( b1 is RelStr-yielding & b1 is non-Empty & b1 is reflexive-yielding )
proof end;
end;

registration
let c1 be set ;
let c2 be RelStr-yielding non-Empty ManySortedSet of c1;
cluster product a2 -> non empty ;
coherence
not product c2 is empty
proof end;
end;

definition
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty ManySortedSet of c1;
let c3 be Element of c1;
redefine func . as c2 . c3 -> non empty RelStr ;
coherence
c2 . c3 is non empty RelStr
proof end;
end;

registration
let c1 be set ;
let c2 be RelStr-yielding non-Empty ManySortedSet of c1;
cluster product a2 -> non empty constituted-Functions ;
coherence
product c2 is constituted-Functions
proof end;
end;

definition
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty ManySortedSet of c1;
let c3 be Element of (product c2);
let c4 be Element of c1;
redefine func . as c3 . c4 -> Element of (a2 . a4);
coherence
c3 . c4 is Element of (c2 . c4)
proof end;
end;

definition
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty ManySortedSet of c1;
let c3 be Element of c1;
let c4 be Subset of (product c2);
redefine func pi as pi c4,c3 -> Subset of (a2 . a3);
coherence
pi c4,c3 is Subset of (c2 . c3)
proof end;
end;

theorem Th27: :: WAYBEL_3:27
for b1 being non empty set
for b2 being RelStr-yielding non-Empty ManySortedSet of b1
for b3 being Function holds
( b3 is Element of (product b2) iff ( dom b3 = b1 & ( for b4 being Element of b1 holds b3 . b4 is Element of (b2 . b4) ) ) )
proof end;

theorem Th28: :: WAYBEL_3:28
for b1 being non empty set
for b2 being RelStr-yielding non-Empty ManySortedSet of b1
for b3, b4 being Element of (product b2) holds
( b3 <= b4 iff for b5 being Element of b1 holds b3 . b5 <= b4 . b5 )
proof end;

definition
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty reflexive-yielding ManySortedSet of c1;
let c3 be Element of c1;
redefine func . as c2 . c3 -> non empty reflexive RelStr ;
coherence
c2 . c3 is non empty reflexive RelStr
proof end;
end;

registration
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty reflexive-yielding ManySortedSet of c1;
cluster product a2 -> non empty reflexive constituted-Functions ;
coherence
product c2 is reflexive
proof end;
end;

definition
let c1 be non empty set ;
let c2 be RelStr-yielding non-Empty reflexive-yielding ManySortedSet of c1;
let c3 be Element of (product c2);
let c4 be Element of c1;
redefine func . as c3 . c4 -> Element of (a2 . a4);
coherence
c3 . c4 is Element of (c2 . c4)
proof end;
end;

theorem Th29: :: WAYBEL_3:29
for b1 being non empty set
for b2 being RelStr-yielding non-Empty ManySortedSet of b1 st ( for b3 being Element of b1 holds b2 . b3 is transitive ) holds
product b2 is transitive
proof end;

theorem Th30: :: WAYBEL_3:30
for b1 being non empty set
for b2 being RelStr-yielding non-Empty ManySortedSet of b1 st ( for b3 being Element of b1 holds b2 . b3 is antisymmetric ) holds
product b2 is antisymmetric
proof end;

theorem Th31: :: WAYBEL_3:31
for b1 being non empty set
for b2 being RelStr-yielding non-Empty reflexive-yielding ManySortedSet of b1 st ( for b3 being Element of b1 holds b2 . b3 is complete LATTICE ) holds
product b2 is complete LATTICE
proof end;

theorem Th32: :: WAYBEL_3:32
for b1 being non empty set
for b2 being RelStr-yielding non-Empty reflexive-yielding ManySortedSet of b1 st ( for b3 being Element of b1 holds b2 . b3 is complete LATTICE ) holds
for b3 being Subset of (product b2)
for b4 being Element of b1 holds (sup b3) . b4 = sup (pi b3,b4)
proof end;

theorem Th33: :: WAYBEL_3:33
for b1 being non empty set
for b2 being RelStr-yielding non-Empty reflexive-yielding ManySortedSet of b1 st ( for b3 being Element of b1 holds b2 . b3 is complete LATTICE ) holds
for b3, b4 being Element of (product b2) holds
( b3 << b4 iff ( ( for b5 being Element of b1 holds b3 . b5 << b4 . b5 ) & ex b5 being finite Subset of b1 st
for b6 being Element of b1 st not b6 in b5 holds
b3 . b6 = Bottom (b2 . b6) ) )
proof end;

theorem Th34: :: WAYBEL_3:34
for b1 being non empty TopSpace
for b2, b3 being Element of (InclPoset the topology of b1) st b2 is_way_below b3 holds
for b4 being Subset-Family of b1 st b4 is open & b3 c= union b4 holds
ex b5 being finite Subset of b4 st b2 c= union b5
proof end;

theorem Th35: :: WAYBEL_3:35
for b1 being non empty TopSpace
for b2, b3 being Element of (InclPoset the topology of b1) st ( for b4 being Subset-Family of b1 st b4 is open & b3 c= union b4 holds
ex b5 being finite Subset of b4 st b2 c= union b5 ) holds
b2 is_way_below b3
proof end;

theorem Th36: :: WAYBEL_3:36
for b1 being non empty TopSpace
for b2 being Element of (InclPoset the topology of b1)
for b3 being Subset of b1 st b2 = b3 holds
( b2 is compact iff b3 is compact )
proof end;

theorem Th37: :: WAYBEL_3:37
for b1 being non empty TopSpace
for b2 being Element of (InclPoset the topology of b1) st b2 = the carrier of b1 holds
( b2 is compact iff b1 is compact )
proof end;

definition
let c1 be non empty TopSpace;
attr a1 is locally-compact means :Def9: :: WAYBEL_3:def 9
for b1 being Point of a1
for b2 being Subset of a1 st b1 in b2 & b2 is open holds
ex b3 being Subset of a1 st
( b1 in Int b3 & b3 c= b2 & b3 is compact );
end;

:: deftheorem Def9 defines locally-compact WAYBEL_3:def 9 :
for b1 being non empty TopSpace holds
( b1 is locally-compact iff for b2 being Point of b1
for b3 being Subset of b1 st b2 in b3 & b3 is open holds
ex b4 being Subset of b1 st
( b2 in Int b4 & b4 c= b3 & b4 is compact ) );

registration
cluster non empty compact being_T2 -> non empty being_T3 being_T4 locally-compact TopStruct ;
coherence
for b1 being non empty TopSpace st b1 is compact & b1 is being_T2 holds
( b1 is being_T3 & b1 is being_T4 & b1 is locally-compact )
proof end;
end;

theorem Th38: :: WAYBEL_3:38
for b1 being set holds 1TopSp {b1} is being_T2
proof end;

registration
cluster non empty compact being_T2 being_T3 being_T4 locally-compact TopStruct ;
existence
ex b1 being non empty TopSpace st
( b1 is compact & b1 is being_T2 )
proof end;
end;

theorem Th39: :: WAYBEL_3:39
for b1 being non empty TopSpace
for b2, b3 being Element of (InclPoset the topology of b1) st ex b4 being Subset of b1 st
( b2 c= b4 & b4 c= b3 & b4 is compact ) holds
b2 << b3
proof end;

theorem Th40: :: WAYBEL_3:40
for b1 being non empty TopSpace st b1 is locally-compact holds
for b2, b3 being Element of (InclPoset the topology of b1) st b2 << b3 holds
ex b4 being Subset of b1 st
( b2 c= b4 & b4 c= b3 & b4 is compact )
proof end;

theorem Th41: :: WAYBEL_3:41
for b1 being non empty TopSpace st b1 is locally-compact & b1 is_T2 holds
for b2, b3 being Element of (InclPoset the topology of b1) st b2 << b3 holds
ex b4 being Subset of b1 st
( b4 = b2 & Cl b4 c= b3 & Cl b4 is compact )
proof end;

theorem Th42: :: WAYBEL_3:42
for b1 being non empty TopSpace st b1 is_T3 & InclPoset the topology of b1 is continuous holds
b1 is locally-compact
proof end;

theorem Th43: :: WAYBEL_3:43
for b1 being non empty TopSpace st b1 is locally-compact holds
InclPoset the topology of b1 is continuous
proof end;