theorem MOB16:
  for b be non trivial Nat, a be non zero Integer holds
    b |-count a <> 0 iff b divides a
proof
  let b be non trivial Nat, a be non zero Integer;
  b |-count |.a.| <> 0 iff b divides |.a.|
  proof
    b <> 1 & a <> 0 by NAT_2:def 1;
    hence thesis by NAT_3:27;
  end;
  hence thesis by INT_2:16;
end;
