MAYBE
MAYBE
TRS:
 {
  ack(s(x), s(y)) -> ack(x, ack(s(x), y)),
   ack(s(x), 0()) -> ack(x, s(0())),
      ack(0(), y) -> s(y)
 }
 DUP: We consider a duplicating system.
  Trs:
   {
    ack(s(x), s(y)) -> ack(x, ack(s(x), y)),
     ack(s(x), 0()) -> ack(x, s(0())),
        ack(0(), y) -> s(y)
   }
  Fail