Let T , S be 1-sorted structures, f be a map from T into S , and P 1 be a subset of the carrier of S . Let S , T be topological structures and let f be a map from S into T . We introduce f is a homeomorphism as a synonym of f is homeomorphism. Let T , S , V be non empty topological structures, f be a map from T into S , and g be a map from S into V . If f is a homeomorphism and g is a homeomorphism, then g f is a homeomorphism.
P is closed.