theorem
  for V being Abelian add-associative right_zeroed
  right_complementable non empty addLoopStr, v,u being Element of V
  holds v - u + u = v
  proof
    let V be Abelian add-associative right_zeroed
    right_complementable non empty addLoopStr, v,u be Element of V;
    thus v - u + u = v - (u-u) by RLVECT_1:29
    .= v - 0.V by RLVECT_1:5
    .= v;
  end;
