MAYBE
Trs:
 {  plus(x, 0()) -> x,
   plus(x, s(y)) -> s(plus(x, y)),
       p(s(0())) -> 0(),
      p(s(s(x))) -> s(p(s(x))),
       fac(s(x)) -> times(fac(p(s(x))), s(x)),
   times(0(), y) -> 0(),
  times(s(x), y) -> plus(times(x, y), y),
   times(x, 0()) -> 0()}
 Comment:
  We consider a duplicating trs.
  FAIL:
   Open