reserve V for non empty RLSStruct;
reserve x,y,y1 for set;
reserve v for VECTOR of V;
reserve a,b for Real;

theorem
  for V being add-associative right_zeroed right_complementable non
  empty addLoopStr, v,w being Element of V holds - (v - w) = w + (- v)
proof
  let V be add-associative right_zeroed right_complementable non empty
  addLoopStr;
  let v,w be Element of V;
  thus - (v - w) = --w + -v by Lm3
    .= w + -v;
end;
