MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { f(true(), x, y) -> f(and(gt(x, y), gt(y, s(s(0())))), plus(s(0()), x), double(y)) , and(x, true()) -> x , and(x, false()) -> false() , gt(s(u), s(v)) -> gt(u, v) , gt(s(u), 0()) -> true() , gt(0(), v) -> false() , plus(n, s(m)) -> s(plus(n, m)) , plus(n, 0()) -> n , double(s(x)) -> s(s(double(x))) , double(0()) -> 0() } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..