
theorem Th36:
  for V,W be VectSp of F_Complex, v,u be Vector of V, w,t be
Vector of W for f be sesquilinear-Form of V,W holds f.(v-u,w-t) = f.(v,w) - f.(
  v,t) -(f.(u,w) - f.(u,t))
proof
  let V,W be VectSp of F_Complex, v1,w1 be Vector of V, w,w2 be Vector of W;
  let f be sesquilinear-Form of V,W;
  set v3 = f.(v1,w) , v4 = f.(v1,w2), v5 = f.(w1,w), v6 = f.(w1,w2);
  thus f.(v1-w1,w-w2) = f.(v1,w-w2) - f.(w1,w-w2) by BILINEAR:35
    .= v3 - v4 - f.(w1,w-w2) by Th35
    .= v3 - v4 - (v5 - v6) by Th35;
end;
