
theorem Th36:
  for x be G_INTEG holds Norm(x) = 0 implies x = 0
  proof
    let x be G_INTEG;
A1: Norm(x)=(Re x+Im x*<i>)*(Re x-(Im x)*<i>) by COMPLEX1:13
    .= (Re x)^2 + (Im x)^2;
    assume Norm(x) = 0;
    hence thesis by A1,COMPLEX1:5;
  end;
