0 QTRS
minus(x, 0) → x minus(s(x), s(y)) → minus(x, y) double(0) → 0 double(s(x)) → s(s(double(x))) plus(0, y) → y plus(s(x), y) → s(plus(x, y)) plus(s(x), y) → plus(x, s(y)) plus(s(x), y) → s(plus(minus(x, y), double(y)))