:: TOPGEN_1 semantic presentation

begin

theorem :: TOPGEN_1:1
for T being ( ( ) ( ) 1-sorted )
for A, B being ( ( ) ( ) Subset of ) holds
( A : ( ( ) ( ) Subset of ) meets B : ( ( ) ( ) Subset of ) ` : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) 1-sorted ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) iff A : ( ( ) ( ) Subset of ) \ B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) 1-sorted ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) <> {} : ( ( ) ( ) set ) ) ;

theorem :: TOPGEN_1:2
for T being ( ( ) ( ) 1-sorted ) holds
( T : ( ( ) ( ) 1-sorted ) is countable iff card ([#] T : ( ( ) ( ) 1-sorted ) ) : ( ( ) ( non proper ) Element of K10( the carrier of b1 : ( ( ) ( ) 1-sorted ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( cardinal ) ( ordinal cardinal ) set ) c= omega : ( ( ) ( ordinal non finite cardinal limit_cardinal ) set ) ) ;

registration
let T be ( ( finite ) ( finite ) 1-sorted ) ;
cluster [#] T : ( ( finite ) ( finite ) 1-sorted ) : ( ( ) ( non proper ) Element of K10( the carrier of T : ( ( finite ) ( finite ) 1-sorted ) : ( ( ) ( finite ) set ) ) : ( ( ) ( non empty ) set ) ) -> finite ;
end;

registration
cluster finite -> countable for ( ( ) ( ) 1-sorted ) ;
end;

registration
cluster non empty countable for ( ( ) ( ) 1-sorted ) ;
cluster non empty TopSpace-like countable for ( ( ) ( ) TopStruct ) ;
end;

registration
let T be ( ( countable ) ( countable ) 1-sorted ) ;
cluster [#] T : ( ( countable ) ( countable ) 1-sorted ) : ( ( ) ( non proper ) Element of K10( the carrier of T : ( ( countable ) ( countable ) 1-sorted ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) -> countable ;
end;

registration
cluster non empty TopSpace-like T_1 for ( ( ) ( ) TopStruct ) ;
end;

begin

theorem :: TOPGEN_1:3
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds Int A : ( ( ) ( ) Subset of ) : ( ( ) ( open ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = (Cl (A : ( ( ) ( ) Subset of ) `) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ` : ( ( ) ( open ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let F be ( ( ) ( ) Subset-Family of ) ;
func Fr F -> ( ( ) ( ) Subset-Family of ) means :: TOPGEN_1:def 1
for A being ( ( ) ( ) Subset of ) holds
( A : ( ( ) ( ) Subset of ) in it : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) iff ex B being ( ( ) ( ) Subset of ) st
( A : ( ( ) ( ) Subset of ) = Fr B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & B : ( ( ) ( ) Subset of ) in F : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ) );
end;

theorem :: TOPGEN_1:4
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) = {} : ( ( ) ( ) set ) holds
Fr F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) = {} : ( ( ) ( ) set ) ;

theorem :: TOPGEN_1:5
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of )
for A being ( ( ) ( ) Subset of ) st F : ( ( ) ( ) Subset-Family of ) = {A : ( ( ) ( ) Subset of ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) Element of K10(K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) holds
Fr F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) = {(Fr A : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) Element of K10(K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:6
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for F, G being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) c= G : ( ( ) ( ) Subset-Family of ) holds
Fr F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) c= Fr G : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) ;

theorem :: TOPGEN_1:7
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for F, G being ( ( ) ( ) Subset-Family of ) holds Fr (F : ( ( ) ( ) Subset-Family of ) \/ G : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Element of K10(K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset-Family of ) = (Fr F : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) \/ (Fr G : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10(K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:8
for T being ( ( ) ( ) TopStruct )
for A being ( ( ) ( ) Subset of ) holds Fr A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = (Cl A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) \ (Int A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( ) ( ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:9
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Fr A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) iff for U being ( ( ) ( ) Subset of ) st U : ( ( ) ( ) Subset of ) is open & p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in U : ( ( ) ( ) Subset of ) holds
( A : ( ( ) ( ) Subset of ) meets U : ( ( ) ( ) Subset of ) & U : ( ( ) ( ) Subset of ) \ A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) <> {} : ( ( ) ( ) set ) ) ) ;

theorem :: TOPGEN_1:10
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Fr A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) iff for B being ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of )
for U being ( ( ) ( ) Subset of ) st U : ( ( ) ( ) Subset of ) in B : ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) holds
( A : ( ( ) ( ) Subset of ) meets U : ( ( ) ( ) Subset of ) & U : ( ( ) ( ) Subset of ) \ A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) <> {} : ( ( ) ( ) set ) ) ) ;

theorem :: TOPGEN_1:11
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Fr A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) iff ex B being ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) st
for U being ( ( ) ( ) Subset of ) st U : ( ( ) ( ) Subset of ) in B : ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) holds
( A : ( ( ) ( ) Subset of ) meets U : ( ( ) ( ) Subset of ) & U : ( ( ) ( ) Subset of ) \ A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) <> {} : ( ( ) ( ) set ) ) ) ;

theorem :: TOPGEN_1:12
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A, B being ( ( ) ( ) Subset of ) holds Fr (A : ( ( ) ( ) Subset of ) /\ B : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) c= ((Cl A : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) /\ (Fr B : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) \/ ((Fr A : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) /\ (Cl B : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:13
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) = ((Int A : ( ( ) ( ) Subset of ) ) : ( ( ) ( open ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) \/ (Fr A : ( ( ) ( ) Subset of ) ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) \/ (Int (A : ( ( ) ( ) Subset of ) `) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ) : ( ( ) ( open ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:14
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds
( ( A : ( ( ) ( ) Subset of ) is open & A : ( ( ) ( ) Subset of ) is closed ) iff Fr A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = {} : ( ( ) ( ) set ) ) ;

begin

definition
let T be ( ( ) ( ) TopStruct ) ;
let A be ( ( ) ( ) Subset of ) ;
let x be ( ( ) ( ) set ) ;
pred x is_an_accumulation_point_of A means :: TOPGEN_1:def 2
x : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) in Cl (A : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) \ {x : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) set ) ) : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:15
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) set ) st x : ( ( ) ( ) set ) is_an_accumulation_point_of A : ( ( ) ( ) Subset of ) holds
x : ( ( ) ( ) set ) is ( ( ) ( ) Point of ( ( ) ( ) set ) ) ;

definition
let T be ( ( ) ( ) TopStruct ) ;
let A be ( ( ) ( ) Subset of ) ;
func Der A -> ( ( ) ( ) Subset of ) means :: TOPGEN_1:def 3
for x being ( ( ) ( ) set ) st x : ( ( ) ( ) set ) in the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) holds
( x : ( ( ) ( ) set ) in it : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) iff x : ( ( ) ( ) set ) is_an_accumulation_point_of A : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) );
end;

theorem :: TOPGEN_1:16
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) set ) holds
( x : ( ( ) ( ) set ) in Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) iff x : ( ( ) ( ) set ) is_an_accumulation_point_of A : ( ( ) ( ) Subset of ) ) ;

theorem :: TOPGEN_1:17
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) iff for U being ( ( open ) ( open ) Subset of ) st x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in U : ( ( open ) ( open ) Subset of ) holds
ex y being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) st
( y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in A : ( ( ) ( ) Subset of ) /\ U : ( ( open ) ( open ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) <> y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) ) ;

theorem :: TOPGEN_1:18
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) iff for B being ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of )
for U being ( ( ) ( ) Subset of ) st U : ( ( ) ( ) Subset of ) in B : ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) holds
ex y being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) st
( y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in A : ( ( ) ( ) Subset of ) /\ U : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) <> y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) ) ;

theorem :: TOPGEN_1:19
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) iff ex B being ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) st
for U being ( ( ) ( ) Subset of ) st U : ( ( ) ( ) Subset of ) in B : ( ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) ( V115(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ,b3 : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) V129(b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) ) Basis of ) holds
ex y being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) st
( y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in A : ( ( ) ( ) Subset of ) /\ U : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & x : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) <> y : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) ) ) ;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
let x be ( ( ) ( ) set ) ;
pred x is_isolated_in A means :: TOPGEN_1:def 4
( x : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) in A : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & not x : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) is_an_accumulation_point_of A : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) );
end;

theorem :: TOPGEN_1:20
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) set ) holds
( p : ( ( ) ( ) set ) in A : ( ( ) ( ) Subset of ) \ (Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) iff p : ( ( ) ( ) set ) is_isolated_in A : ( ( ) ( ) Subset of ) ) ;

theorem :: TOPGEN_1:21
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) is_an_accumulation_point_of A : ( ( ) ( ) Subset of ) iff for U being ( ( open ) ( open ) Subset of ) st p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in U : ( ( open ) ( open ) Subset of ) holds
ex q being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) st
( q : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) <> p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) & q : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in A : ( ( ) ( ) Subset of ) & q : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) in U : ( ( open ) ( open ) Subset of ) ) ) ;

theorem :: TOPGEN_1:22
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for p being ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) holds
( p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) is_isolated_in A : ( ( ) ( ) Subset of ) iff ex G being ( ( open ) ( open ) Subset of ) st G : ( ( open ) ( open ) Subset of ) /\ A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = {p : ( ( ) ( ) Point of ( ( ) ( non empty ) set ) ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) set ) ) ;

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let p be ( ( ) ( ) Point of ( ( ) ( ) set ) ) ;
attr p is isolated means :: TOPGEN_1:def 5
p : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) is_isolated_in [#] T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty non proper ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:23
errorfrm ;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let F be ( ( ) ( ) Subset-Family of ) ;
func Der F -> ( ( ) ( ) Subset-Family of ) means :: TOPGEN_1:def 6
for A being ( ( ) ( ) Subset of ) holds
( A : ( ( ) ( ) Subset of ) in it : ( ( ) ( ) Element of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) iff ex B being ( ( ) ( ) Subset of ) st
( A : ( ( ) ( ) Subset of ) = Der B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) & B : ( ( ) ( ) Subset of ) in F : ( ( ) ( ) Element of K10(K10(T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ) );
end;

theorem :: TOPGEN_1:24
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) = {} : ( ( ) ( ) set ) holds
Der F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) = {} : ( ( ) ( ) set ) ;

theorem :: TOPGEN_1:25
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of )
for F being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) = {A : ( ( ) ( ) Subset of ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) Element of K10(K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) holds
Der F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) = {(Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) } : ( ( ) ( non empty V2() 1 : ( ( ) ( non empty ) set ) -element ) Element of K10(K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:26
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F, G being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) c= G : ( ( ) ( ) Subset-Family of ) holds
Der F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) c= Der G : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Subset-Family of ) ;

theorem :: TOPGEN_1:27
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F, G being ( ( ) ( ) Subset-Family of ) holds Der (F : ( ( ) ( ) Subset-Family of ) \/ G : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Element of K10(K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset-Family of ) = (Der F : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) \/ (Der G : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10(K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:28
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) c= Cl A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:29
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds Cl A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = A : ( ( ) ( ) Subset of ) \/ (Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:30
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A, B being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) c= B : ( ( ) ( ) Subset of ) holds
Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) c= Der B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) ;

theorem :: TOPGEN_1:31
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A, B being ( ( ) ( ) Subset of ) holds Der (A : ( ( ) ( ) Subset of ) \/ B : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset of ) = (Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) \/ (Der B : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:32
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) st T : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) is T_1 holds
Der (Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) c= Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) ;

theorem :: TOPGEN_1:33
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) st T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) is T_1 holds
Cl (Der A : ( ( ) ( ) Subset of ) ) : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) ;

registration
let T be ( ( non empty TopSpace-like T_1 ) ( non empty TopSpace-like T_1 ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
cluster Der A : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like T_1 ) ( non empty TopSpace-like T_1 ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset of ) -> closed ;
end;

theorem :: TOPGEN_1:34
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of ) holds union (Der F : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) c= Der (union F : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset of ) ;

theorem :: TOPGEN_1:35
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A, B being ( ( ) ( ) Subset of )
for x being ( ( ) ( ) set ) st A : ( ( ) ( ) Subset of ) c= B : ( ( ) ( ) Subset of ) & x : ( ( ) ( ) set ) is_an_accumulation_point_of A : ( ( ) ( ) Subset of ) holds
x : ( ( ) ( ) set ) is_an_accumulation_point_of B : ( ( ) ( ) Subset of ) ;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
attr A is dense-in-itself means :: TOPGEN_1:def 7
A : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) c= Der A : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset of ) ;
end;

definition
let T be ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ;
attr T is dense-in-itself means :: TOPGEN_1:def 8
[#] T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty non proper ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) is dense-in-itself ;
end;

theorem :: TOPGEN_1:36
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) st T : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) is T_1 & A : ( ( ) ( ) Subset of ) is dense-in-itself holds
Cl A : ( ( ) ( ) Subset of ) : ( ( ) ( closed ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) is dense-in-itself ;

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let F be ( ( ) ( ) Subset-Family of ) ;
attr F is dense-in-itself means :: TOPGEN_1:def 9
for A being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) in F : ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty V105() V106() V107() V108() ) ( non empty V105() V106() V107() V108() ) L7()) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) holds
A : ( ( ) ( ) Subset of ) is dense-in-itself ;
end;

theorem :: TOPGEN_1:37
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) is dense-in-itself holds
union F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) c= union (Der F : ( ( ) ( ) Subset-Family of ) ) : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:38
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace)
for F being ( ( ) ( ) Subset-Family of ) st F : ( ( ) ( ) Subset-Family of ) is dense-in-itself holds
union F : ( ( ) ( ) Subset-Family of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) is dense-in-itself ;

theorem :: TOPGEN_1:39
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) holds Fr ({} T : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ) : ( ( ) ( empty proper ordinal cardinal {} : ( ( ) ( ) set ) -element open boundary nowhere_dense ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed boundary nowhere_dense ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = {} : ( ( ) ( ) set ) ;

registration
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let A be ( ( open closed ) ( open closed ) Subset of ) ;
cluster Fr A : ( ( open closed ) ( open closed ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed boundary nowhere_dense ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) -> empty ;
end;

registration
let T be ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopSpace) ;
cluster non open for ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) ;
cluster non closed for ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

registration
let T be ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopSpace) ;
let A be ( ( non open ) ( non open ) Subset of ) ;
cluster Fr A : ( ( non open ) ( non open ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) -> non empty ;
end;

registration
let T be ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopSpace) ;
let A be ( ( non closed ) ( non closed ) Subset of ) ;
cluster Fr A : ( ( non closed ) ( non closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) -> non empty ;
end;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
attr A is perfect means :: TOPGEN_1:def 10
( A : ( ( non closed ) ( non closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) is closed & A : ( ( non closed ) ( non closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) is dense-in-itself );
end;

registration
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
cluster perfect -> closed dense-in-itself for ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) ;
cluster closed dense-in-itself -> perfect for ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:40
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) holds Der ({} T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ) : ( ( ) ( empty ordinal cardinal {} : ( ( ) ( ) set ) -element open boundary nowhere_dense ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( ) Subset of ) = {} T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( empty ordinal cardinal {} : ( ( ) ( ) set ) -element open boundary nowhere_dense ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:41
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace)
for A being ( ( ) ( ) Subset of ) holds
( A : ( ( ) ( ) Subset of ) is perfect iff Der A : ( ( ) ( ) Subset of ) : ( ( ) ( ) Subset of ) = A : ( ( ) ( ) Subset of ) ) ;

theorem :: TOPGEN_1:42
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) holds {} T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( empty ordinal cardinal {} : ( ( ) ( ) set ) -element open boundary nowhere_dense ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) is perfect ;

registration
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
cluster empty -> perfect for ( ( ) ( ) Element of K10( the carrier of T : ( ( non empty TopSpace-like non discrete ) ( non empty V47() TopSpace-like non discrete ) TopStruct ) : ( ( ) ( non empty V2() ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

registration
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
cluster perfect for ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
attr A is scattered means :: TOPGEN_1:def 11
for B being ( ( ) ( ) Subset of ) holds
( B : ( ( ) ( ) Subset of ) is empty or not B : ( ( ) ( ) Subset of ) c= A : ( ( non closed ) ( non closed ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) or not B : ( ( ) ( ) Subset of ) is dense-in-itself );
end;

registration
let T be ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) ;
cluster non empty scattered -> non dense-in-itself for ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;
cluster non empty dense-in-itself -> non scattered for ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:43
for T being ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) holds {} T : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( empty ordinal cardinal {} : ( ( ) ( ) set ) -element open closed boundary nowhere_dense dense-in-itself perfect ) Element of K10( the carrier of b1 : ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) is scattered ;

registration
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
cluster empty -> scattered for ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:44
for T being ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) st T : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) is T_1 holds
ex A, B being ( ( ) ( ) Subset of ) st
( A : ( ( ) ( ) Subset of ) \/ B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = [#] T : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty non proper open dense non boundary ) Element of K10( the carrier of b1 : ( ( non empty TopSpace-like ) ( non empty TopSpace-like ) TopSpace) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) & A : ( ( ) ( ) Subset of ) misses B : ( ( ) ( ) Subset of ) & A : ( ( ) ( ) Subset of ) is perfect & B : ( ( ) ( ) Subset of ) is scattered ) ;

registration
let T be ( ( TopSpace-like discrete ) ( TopSpace-like discrete ) TopSpace) ;
let A be ( ( ) ( ) Subset of ) ;
cluster Fr A : ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like discrete ) ( TopSpace-like discrete ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( closed ) Element of K10( the carrier of T : ( ( TopSpace-like discrete ) ( TopSpace-like discrete ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) -> empty ;
end;

registration
let T be ( ( TopSpace-like discrete ) ( TopSpace-like discrete ) TopSpace) ;
cluster -> open closed for ( ( ) ( ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;
end;

theorem :: TOPGEN_1:45
for T being ( ( TopSpace-like discrete ) ( TopSpace-like discrete ) TopSpace)
for A being ( ( ) ( open closed ) Subset of ) holds Der A : ( ( ) ( open closed ) Subset of ) : ( ( ) ( open closed ) Subset of ) = {} : ( ( ) ( ) set ) ;

registration
let T be ( ( non empty TopSpace-like discrete ) ( non empty TopSpace-like T_1 T_2 V64() normal discrete ) TopSpace) ;
let A be ( ( ) ( open closed ) Subset of ) ;
cluster Der A : ( ( ) ( open closed ) Element of K10( the carrier of T : ( ( non empty TopSpace-like discrete ) ( non empty TopSpace-like T_1 T_2 V64() normal discrete ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( open closed ) Subset of ) -> empty ;
end;

begin

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
func density T -> ( ( cardinal ) ( ordinal cardinal ) number ) means :: TOPGEN_1:def 12
( ex A being ( ( ) ( ) Subset of ) st
( A : ( ( ) ( ) Subset of ) is dense & it : ( ( ) ( open closed ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) = card A : ( ( ) ( ) Subset of ) : ( ( cardinal ) ( ordinal cardinal ) set ) ) & ( for B being ( ( ) ( ) Subset of ) st B : ( ( ) ( ) Subset of ) is dense holds
it : ( ( ) ( open closed ) Element of K10( the carrier of T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) c= card B : ( ( ) ( ) Subset of ) : ( ( cardinal ) ( ordinal cardinal ) set ) ) );
end;

definition
let T be ( ( TopSpace-like ) ( TopSpace-like ) TopSpace) ;
attr T is separable means :: TOPGEN_1:def 13
density T : ( ( TopSpace-like ) ( TopSpace-like ) TopStruct ) : ( ( cardinal ) ( ordinal cardinal ) number ) c= omega : ( ( ) ( ordinal non finite cardinal limit_cardinal ) set ) ;
end;

theorem :: TOPGEN_1:46
for T being ( ( TopSpace-like countable ) ( TopSpace-like countable ) TopSpace) holds T : ( ( TopSpace-like countable ) ( TopSpace-like countable ) TopSpace) is separable ;

registration
cluster TopSpace-like countable -> TopSpace-like separable for ( ( ) ( ) TopStruct ) ;
end;

begin

theorem :: TOPGEN_1:47
for A being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) = RAT : ( ( ) ( ) set ) holds
A : ( ( ) ( ) Subset of ) ` : ( ( ) ( ) Element of K10( the carrier of R^1 : ( ( TopSpace-like ) ( non empty strict TopSpace-like V114() ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = IRRAT : ( ( ) ( ) Element of K10(REAL : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) ;

theorem :: TOPGEN_1:48
for A being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) = IRRAT : ( ( ) ( ) Element of K10(REAL : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) holds
A : ( ( ) ( ) Subset of ) ` : ( ( ) ( ) Element of K10( the carrier of R^1 : ( ( TopSpace-like ) ( non empty strict TopSpace-like V114() ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = RAT : ( ( ) ( ) set ) ;

theorem :: TOPGEN_1:49
for A being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) = RAT : ( ( ) ( ) set ) holds
Int A : ( ( ) ( ) Subset of ) : ( ( ) ( open ) Element of K10( the carrier of R^1 : ( ( TopSpace-like ) ( non empty strict TopSpace-like V114() ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = {} : ( ( ) ( ) set ) ;

theorem :: TOPGEN_1:50
for A being ( ( ) ( ) Subset of ) st A : ( ( ) ( ) Subset of ) = IRRAT : ( ( ) ( ) Element of K10(REAL : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) holds
Int A : ( ( ) ( ) Subset of ) : ( ( ) ( open ) Element of K10( the carrier of R^1 : ( ( TopSpace-like ) ( non empty strict TopSpace-like V114() ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) = {} : ( ( ) ( ) set ) ;

theorem :: TOPGEN_1:51
RAT : ( ( ) ( ) set ) is ( ( dense ) ( dense ) Subset of ) ;

theorem :: TOPGEN_1:52
IRRAT : ( ( ) ( ) Element of K10(REAL : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) is ( ( dense ) ( dense ) Subset of ) ;

theorem :: TOPGEN_1:53
RAT : ( ( ) ( ) set ) is ( ( boundary ) ( boundary ) Subset of ) ;

theorem :: TOPGEN_1:54
IRRAT : ( ( ) ( ) Element of K10(REAL : ( ( ) ( ) set ) ) : ( ( ) ( non empty ) set ) ) is ( ( boundary ) ( boundary ) Subset of ) ;

theorem :: TOPGEN_1:55
REAL : ( ( ) ( ) set ) is ( ( non boundary ) ( non boundary ) Subset of ) ;

theorem :: TOPGEN_1:56
ex A, B being ( ( ) ( ) Subset of ) st
( A : ( ( ) ( ) Subset of ) is boundary & B : ( ( ) ( ) Subset of ) is boundary & not A : ( ( ) ( ) Subset of ) \/ B : ( ( ) ( ) Subset of ) : ( ( ) ( ) Element of K10( the carrier of R^1 : ( ( TopSpace-like ) ( non empty strict TopSpace-like V114() ) TopStruct ) : ( ( ) ( non empty ) set ) ) : ( ( ) ( non empty ) set ) ) is boundary ) ;