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