YES(?,O(n^1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { f(0()) -> s(0()) , f(s(0())) -> s(s(0())) , f(s(0())) -> *(s(s(0())), f(0())) , f(+(x, y)) -> *(f(x), f(y)) , f(+(x, s(0()))) -> +(s(s(0())), f(x)) } Obligation: innermost runtime complexity Answer: YES(?,O(n^1)) The problem is match-bounded by 2. The enriched problem is compatible with the following automaton. { f_0(2) -> 1 , f_0(3) -> 1 , f_0(4) -> 1 , f_0(5) -> 1 , f_1(2) -> 1 , f_1(2) -> 7 , f_1(3) -> 7 , f_1(4) -> 7 , f_1(5) -> 7 , f_1(6) -> 7 , 0_0() -> 2 , 0_1() -> 6 , 0_2() -> 8 , s_0(2) -> 3 , s_0(3) -> 3 , s_0(4) -> 3 , s_0(5) -> 3 , s_1(1) -> 1 , s_1(6) -> 1 , s_1(6) -> 7 , s_1(7) -> 7 , s_2(8) -> 7 , *_0(2, 2) -> 4 , *_0(2, 3) -> 4 , *_0(2, 4) -> 4 , *_0(2, 5) -> 4 , *_0(3, 2) -> 4 , *_0(3, 3) -> 4 , *_0(3, 4) -> 4 , *_0(3, 5) -> 4 , *_0(4, 2) -> 4 , *_0(4, 3) -> 4 , *_0(4, 4) -> 4 , *_0(4, 5) -> 4 , *_0(5, 2) -> 4 , *_0(5, 3) -> 4 , *_0(5, 4) -> 4 , *_0(5, 5) -> 4 , *_1(1, 7) -> 1 , *_1(7, 7) -> 1 , *_1(7, 7) -> 7 , +_0(2, 2) -> 5 , +_0(2, 3) -> 5 , +_0(2, 4) -> 5 , +_0(2, 5) -> 5 , +_0(3, 2) -> 5 , +_0(3, 3) -> 5 , +_0(3, 4) -> 5 , +_0(3, 5) -> 5 , +_0(4, 2) -> 5 , +_0(4, 3) -> 5 , +_0(4, 4) -> 5 , +_0(4, 5) -> 5 , +_0(5, 2) -> 5 , +_0(5, 3) -> 5 , +_0(5, 4) -> 5 , +_0(5, 5) -> 5 , +_1(1, 7) -> 1 , +_1(1, 7) -> 7 } Hurray, we answered YES(?,O(n^1))