
theorem Th34:
  for x, y be G_RAT holds Norm(x*y) = Norm(x)*Norm(y)
  proof
    let x, y be G_RAT;
    thus Norm(x*y) = (x * y) * ((x *') * (y *')) by COMPLEX1:35
    .= Norm(x) * Norm(y);
  end;
