Let X be a set and let Y be an empty set. Let X be an empty set and let Y be a set. Let X , Y be non empty topological spaces and x be a point of X . Let T be a non empty topological structure.
T is homeomorphism.
Let S , T be non empty topological structures. Let us notice that the predicate S and T are homeomorphic is reflexive and symmetric. Next we state the proposition Let S , T , V be non empty topological spaces. Suppose S and T are homeomorphic and T and V are homeomorphic. Then S and V are homeomorphic.