reserve F for Field,
  x for Element of F,
  V for VectSp of F,
  v for Element of V;

theorem Th24:
  for F being add-associative right_zeroed right_complementable
  non empty addLoopStr, a being Element of F holds -a = 0.F implies a = 0.F
proof
  let F be add-associative right_zeroed right_complementable non empty
  addLoopStr, a be Element of F;
  --a = a by RLVECT_1:17;
  hence thesis by RLVECT_1:12;
end;
