theorem
  Lin(A) = (0).V implies A = {} or A = {0.V}
proof
  assume that
A1: Lin(A) = (0).V and
A2: A <> {};
  thus A c= {0.V}
  proof
    let x be object;
    assume x in A;
    then x in Lin(A) by Th68;
    then x = 0.V by A1,RMOD_2:35;
    hence thesis by TARSKI:def 1;
  end;
  set y = the Element of A;
  let x be object;
  assume x in {0.V};
  then
A3: x = 0.V by TARSKI:def 1;
  y in A & y in Lin(A) by A2,Th68;
  hence thesis by A1,A3,RMOD_2:35;
end;
