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)) -> mark(f(f(x))) , f(active(x)) -> active(f(x)) , f(mark(x)) -> mark(f(x)) , f(no(x)) -> no(f(x)) , chk(no(f(x))) -> f(chk(mat(f(f(f(f(f(f(f(f(f(f(X())))))))))), x))) , chk(no(c())) -> active(c()) , mat(f(x), f(y())) -> f(mat(x, y())) , mat(f(x), c()) -> no(c()) , tp(mark(x)) -> tp(chk(mat(f(f(f(f(f(f(f(f(f(f(X())))))))))), 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. { active_0(2) -> 1 , active_1(4) -> 1 , active_2(18) -> 5 , f_0(2) -> 1 , f_1(2) -> 3 , f_1(8) -> 7 , f_1(9) -> 8 , f_1(10) -> 9 , f_1(11) -> 10 , f_1(12) -> 11 , f_1(13) -> 12 , f_1(14) -> 13 , f_1(15) -> 14 , f_1(16) -> 15 , f_1(17) -> 16 , mark_0(2) -> 2 , mark_1(3) -> 1 , mark_1(3) -> 3 , chk_0(2) -> 1 , chk_1(6) -> 5 , no_0(2) -> 2 , no_1(3) -> 1 , no_1(3) -> 3 , no_1(4) -> 6 , mat_0(2, 2) -> 1 , mat_1(7, 2) -> 6 , X_0() -> 2 , X_1() -> 17 , y_0() -> 2 , c_0() -> 2 , c_1() -> 4 , c_2() -> 18 , tp_0(2) -> 1 , tp_1(5) -> 1 } Hurray, we answered YES(?,O(n^1))