 reserve n,k for Nat;
 reserve L for comRing;
 reserve R for domRing;
 reserve x0 for positive Real;

theorem Th12:
  for L be non degenerated domRing, n be non zero Nat,
    a be non zero Element of L st Char L = 0 holds n*a <> 0.L
    proof
      let L be non degenerated domRing;
      let n be non zero Nat, a be non zero Element of L;
      n*a = n'*'a by RING_3:def 2;
      hence thesis by REALALG2:25;
    end;
