YES(?,O(n^1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { active(f(X)) -> f(active(X)) , active(f(f(X))) -> mark(c(f(g(f(X))))) , active(c(X)) -> mark(d(X)) , active(h(X)) -> mark(c(d(X))) , active(h(X)) -> h(active(X)) , f(mark(X)) -> mark(f(X)) , f(ok(X)) -> ok(f(X)) , c(ok(X)) -> ok(c(X)) , g(ok(X)) -> ok(g(X)) , d(ok(X)) -> ok(d(X)) , h(mark(X)) -> mark(h(X)) , h(ok(X)) -> ok(h(X)) , proper(f(X)) -> f(proper(X)) , proper(c(X)) -> c(proper(X)) , proper(g(X)) -> g(proper(X)) , proper(d(X)) -> d(proper(X)) , proper(h(X)) -> h(proper(X)) , top(mark(X)) -> top(proper(X)) , top(ok(X)) -> top(active(X)) } 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. { active_0(2) -> 1 , active_1(2) -> 4 , f_0(2) -> 1 , f_1(2) -> 3 , mark_0(2) -> 2 , mark_1(3) -> 1 , mark_1(3) -> 3 , c_0(2) -> 1 , c_1(2) -> 3 , g_0(2) -> 1 , g_1(2) -> 3 , d_0(2) -> 1 , d_1(2) -> 3 , h_0(2) -> 1 , h_1(2) -> 3 , proper_0(2) -> 1 , proper_1(2) -> 4 , ok_0(2) -> 2 , ok_1(3) -> 1 , ok_1(3) -> 3 , top_0(2) -> 1 , top_1(4) -> 1 } Hurray, we answered YES(?,O(n^1))