We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { a(c(d(x))) -> c(x) , u(b(d(d(x)))) -> b(x) , v(a(a(x))) -> u(v(x)) , v(a(c(x))) -> u(b(d(x))) , v(c(x)) -> b(x) , w(a(a(x))) -> u(w(x)) , w(a(c(x))) -> u(b(d(x))) , w(c(x)) -> b(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. { a_0(2) -> 1 , a_0(3) -> 1 , a_0(5) -> 1 , c_0(2) -> 2 , c_0(3) -> 2 , c_0(5) -> 2 , c_1(2) -> 1 , c_1(3) -> 1 , c_1(5) -> 1 , d_0(2) -> 3 , d_0(3) -> 3 , d_0(5) -> 3 , u_0(2) -> 4 , u_0(3) -> 4 , u_0(5) -> 4 , b_0(2) -> 5 , b_0(3) -> 5 , b_0(5) -> 5 , b_1(2) -> 4 , b_1(2) -> 6 , b_1(2) -> 7 , b_1(3) -> 4 , b_1(3) -> 6 , b_1(3) -> 7 , b_1(5) -> 4 , b_1(5) -> 6 , b_1(5) -> 7 , v_0(2) -> 6 , v_0(3) -> 6 , v_0(5) -> 6 , w_0(2) -> 7 , w_0(3) -> 7 , w_0(5) -> 7 } Hurray, we answered YES(?,O(n^1))