% problem-set/topology/point.set/lemma16.clauses
% created : 08/08/88
% revised : 08/17/89

% description : 
% 
% lemma 16: The closure of a subset ya of a subspace y of space x is 
% 	the same as its closure in x under topology xt.

% representation : 
%
% See axioms.decl for a full explanation.

% denial: 

top_space(X,T).
subset_s(A,Y).
-eq_s(closure(A,X,T),intersect(Y,closure(A,Y,subspace_top(X,T,Y)))).