
theorem Th1:
  for L being add-associative right_zeroed right_complementable
  non empty addLoopStr, a, b being Element of L holds a - b + b = a
proof
  let L be add-associative right_zeroed right_complementable non empty
  addLoopStr, a, b be Element of L;
  thus a-b+b = a+(-b+b) by RLVECT_1:def 3
    .= a+0.L by RLVECT_1:5
    .= a by RLVECT_1:def 4;
end;
