
theorem
  for T being non empty TopSpace st T is sequential holds T is Frechet
iff for A,B being Subset of T holds Cl_Seq({}T) = {} & A c= Cl_Seq(A) & Cl_Seq(
A \/ B) = Cl_Seq(A) \/ Cl_Seq(B) & Cl_Seq(Cl_Seq(A)) = Cl_Seq(A) by Th21,Th22;
