MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { digits() -> d(0()) , d(x) -> if(le(x, s(s(s(s(s(s(s(s(s(0())))))))))), x) , if(true(), x) -> cons(x, d(s(x))) , if(false(), x) -> nil() , le(0(), y) -> true() , le(s(x), 0()) -> false() , le(s(x), s(y)) -> le(x, y) } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..