MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { +(0(), y) -> y , +(s(x), y) -> s(+(x, y)) , *(x, 0()) -> 0() , *(x, s(y)) -> +(x, *(x, y)) , twice(0()) -> 0() , twice(s(x)) -> s(s(twice(x))) , -(x, 0()) -> x , -(s(x), s(y)) -> -(x, y) , f(s(x)) -> f(-(*(s(s(x)), s(s(x))), +(*(s(x), s(s(x))), s(s(0()))))) } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..