reserve G,F for RealLinearSpace;

theorem Th4:
  for X be non empty set
  ex I be Function of X,product <*X*>
  st I is one-to-one & I is onto
  & for x be object st x in X holds I.x = <*x*>
  proof
    let X be non empty set;
    dom <*X*> = {1} & <*X*>.1 = X by FINSEQ_1:2,38;
    hence thesis by Th2;
  end;
