% problem-set/topology/point.set/lemma18.clauses % created : 08/08/88 % revised : 08/17/89 % description : % % lemma 18: For any subset xa of topological space (x,xt), closure(xa) % equals xa union limit_pt_set(xa). % representation : % % See axioms.decl for a full explanation. % denial: top_space(X,T). subset_s(A,X). -eq_s(closure(A,X,T),join(A,limit_pt_set(A))).