0 QTRS
-(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)))