We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { f(x, h1(y, z)) -> h2(0(), x, h1(y, z)) , f(j(x, y), y) -> g(f(x, k(y))) , g(h2(x, y, h1(z, u))) -> h2(s(x), y, h1(z, u)) , k(h1(x, y)) -> h1(s(x), y) , k(h(x)) -> h1(0(), x) , h2(x, j(y, h1(z, u)), h1(z, u)) -> h2(s(x), y, h1(s(z), u)) , i(f(x, h(y))) -> y , i(h2(s(x), y, h1(x, z))) -> z } 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, 2) -> 1 , f_1(2, 6) -> 5 , j_0(2, 2) -> 2 , g_0(2) -> 1 , g_1(5) -> 1 , g_1(5) -> 5 , k_0(2) -> 1 , k_1(2) -> 6 , h1_0(2, 2) -> 2 , h1_1(2, 2) -> 4 , h1_1(3, 2) -> 1 , h1_1(3, 2) -> 6 , h1_1(7, 2) -> 1 , h1_1(7, 2) -> 6 , h1_2(3, 2) -> 9 , h1_2(7, 2) -> 9 , h2_0(2, 2, 2) -> 1 , h2_1(3, 2, 4) -> 1 , h2_1(7, 2, 6) -> 1 , h2_1(7, 2, 6) -> 5 , h2_1(11, 2, 6) -> 5 , h2_2(8, 2, 9) -> 5 , h2_2(10, 2, 9) -> 1 , h2_2(10, 2, 9) -> 5 , 0_0() -> 2 , 0_1() -> 3 , 0_2() -> 8 , s_0(2) -> 2 , s_1(2) -> 7 , s_1(3) -> 7 , s_1(7) -> 7 , s_1(8) -> 11 , s_1(10) -> 7 , s_1(11) -> 7 , s_2(7) -> 10 , s_2(8) -> 10 , s_2(10) -> 10 , s_2(11) -> 10 , i_0(2) -> 1 , h_0(2) -> 2 } Hurray, we answered YES(?,O(n^1))