MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { nats() -> adx(zeros()) , adx(cons(X, Y)) -> incr(cons(X, adx(Y))) , zeros() -> cons(0(), zeros()) , incr(cons(X, Y)) -> cons(s(X), incr(Y)) , hd(cons(X, Y)) -> X , tl(cons(X, Y)) -> Y } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..