
theorem ::p.122 lemma 3.4.(iii)
  for T being T_0-TopSpace st T is injective ex M being non empty set st
  T is_Retract_of product (M --> Sierpinski_Space)
proof
  let T be T_0-TopSpace;
  assume
A1: T is injective;
  ex M being non empty set, f being Function of T, product (M -->
  Sierpinski_Space) st corestr(f) is being_homeomorphism by Th18;
  hence thesis by A1,Th11;
end;
