TRS: { -(x, 0()) -> x, -(s(x), s(y)) -> -(x, y), p(s(x)) -> x, f(s(x), y) -> f(p(-(s(x), y)), p(-(y, s(x)))), f(x, s(y)) -> f(p(-(x, s(y))), p(-(s(y), x)))} Fail