MAYBE
MAYBE
TRS:
 {
            i(0()) -> 0(),
           i(i(x)) -> x,
        i(+(x, y)) -> +(i(x), i(y)),
         +(x, 0()) -> x,
        +(x, i(x)) -> 0(),
     +(x, +(y, z)) -> +(+(x, y), z),
         +(0(), y) -> y,
        +(i(x), x) -> 0(),
  +(+(x, y), i(y)) -> x,
  +(+(x, i(y)), y) -> x
 }
 Fail