YES(?,O(n^1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { f(c(s(x), y)) -> f(c(x, s(y))) , g(c(x, s(y))) -> g(c(s(x), y)) , g(s(f(x))) -> g(f(x)) } Obligation: runtime complexity Answer: YES(?,O(n^1)) The problem is match-bounded by 1. The enriched problem is compatible with the following automaton. { f_0(2) -> 1 , f_1(3) -> 1 , c_0(2, 2) -> 2 , c_1(2, 4) -> 3 , c_1(4, 2) -> 5 , s_0(2) -> 2 , s_1(2) -> 4 , s_1(4) -> 4 , g_0(2) -> 1 , g_1(5) -> 1 } Hurray, we answered YES(?,O(n^1))