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