scheme :: TOPGEN_3:sch 2
TopDefByClosureOp{ F1() -> set , F2( object ) -> set } :
ex T being strict TopSpace st
( the carrier of T = F1() & ( for A being Subset of T holds Cl A = F2(A) ) )
provided
A1: F2({}) = {} and
A2: for A being Subset of F1() holds
( A c= F2(A) & F2(A) c= F1() ) and
A3: for A, B being Subset of F1() holds F2((A \/ B)) = F2(A) \/ F2(B) and
A4: for A being Subset of F1() holds F2(F2(A)) = F2(A)