
theorem AP2:
  for a,b,x,y be Complex holds <*a,b*>+<*x,y*> = <*a+x,b+y*>
  proof
    let a,b,x,y be Complex;
    <*a,b*>+<*x,y*>  = (<*a*>+<*x*>)^<*(b+y)*> by FPA;
    hence thesis by APB;
  end;
