YES(?,PRIMREC) We are left with following problem, upon which TcT provides the certificate YES(?,PRIMREC). Strict Trs: { g(0()) -> 0() , g(s(x)) -> f(g(x)) , f(0()) -> 0() } Obligation: innermost runtime complexity Answer: YES(?,PRIMREC) The input was oriented with the instance of'multiset path order' as induced by the precedence g > f, 0 > f, s > f, g ~ 0, g ~ s, 0 ~ s . Hurray, we answered YES(?,PRIMREC)