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