MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { from(X) -> cons(X, n__from(s(X))) , from(X) -> n__from(X) , head(cons(X, XS)) -> X , 2nd(cons(X, XS)) -> head(activate(XS)) , activate(X) -> X , activate(n__from(X)) -> from(X) , activate(n__take(X1, X2)) -> take(X1, X2) , take(X1, X2) -> n__take(X1, X2) , take(s(N), cons(X, XS)) -> cons(X, n__take(N, activate(XS))) , take(0(), XS) -> nil() , sel(s(N), cons(X, XS)) -> sel(N, activate(XS)) , sel(0(), cons(X, XS)) -> X } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..