
theorem Th31:
  for V being RealUnitarySpace, W1,W2 being Subspace of V holds (0).W1 = (0).W2
proof
  let V be RealUnitarySpace;
  let W1,W2 be Subspace of V;
  (0).W1 = (0).V by Th30;
  hence thesis by Th30;
end;
