YES(?,O(n^1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { +(+(x, y), z) -> +(x, +(y, z)) , +(*(x, y), +(*(x, z), u())) -> +(*(x, +(y, z)), u()) , +(*(x, y), *(x, z)) -> *(x, +(y, z)) } Obligation: innermost runtime complexity Answer: YES(?,O(n^1)) The problem is match-bounded by 1. The enriched problem is compatible with the following automaton. { +_0(2, 2) -> 1 , +_0(2, 3) -> 1 , +_0(3, 2) -> 1 , +_0(3, 3) -> 1 , +_1(2, 2) -> 4 , +_1(2, 3) -> 4 , +_1(3, 2) -> 4 , +_1(3, 3) -> 4 , *_0(2, 2) -> 2 , *_0(2, 3) -> 2 , *_0(3, 2) -> 2 , *_0(3, 3) -> 2 , *_1(2, 4) -> 1 , *_1(2, 4) -> 4 , *_1(3, 4) -> 1 , *_1(3, 4) -> 4 , u_0() -> 3 } Hurray, we answered YES(?,O(n^1))