MAYBE
Trs:
 {             plus(0(), x) -> x,
              plus(s(x), y) -> s(plus(x, y)),
              times(0(), y) -> 0(),
             times(s(x), y) -> plus(y, times(x, y)),
                tower(x, y) -> towerIter(0(), x, y, s(0())),
              ge(0(), s(x)) -> false(),
             ge(s(x), s(y)) -> ge(x, y),
                 ge(x, 0()) -> true(),
   help(true(), c, x, y, z) -> z,
  help(false(), c, x, y, z) -> towerIter(s(c), x, y, exp(y, z)),
                exp(x, 0()) -> s(0()),
               exp(x, s(y)) -> times(x, exp(x, y)),
      towerIter(c, x, y, z) -> help(ge(c, x), c, x, y, z)}
 Comment:
  We consider a duplicating trs.
  FAIL:
   Open