YES(?,ELEMENTARY) We are left with following problem, upon which TcT provides the certificate YES(?,ELEMENTARY). Strict Trs: { *(x, +(y, z)) -> +(*(x, y), *(x, z)) , *(x, 1()) -> x , *(+(x, y), z) -> +(*(x, z), *(y, z)) , *(1(), y) -> y } Obligation: innermost runtime complexity Answer: YES(?,ELEMENTARY) The input was oriented with the instance of 'Lightweight Multiset Path Order' as induced by the safe mapping safe(*) = {}, safe(+) = {1, 2}, safe(1) = {} and precedence empty . Following symbols are considered recursive: {*} The recursion depth is 1. For your convenience, here are the satisfied ordering constraints: *(x, +(; y, z);) > +(; *(x, y;), *(x, z;)) *(x, 1();) > x *(+(; x, y), z;) > +(; *(x, z;), *(y, z;)) *(1(), y;) > y Hurray, we answered YES(?,ELEMENTARY)