YES(?,O(1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(1)). Strict Trs: { f(c(a(), z, x)) -> b(a(), z) , b(y, z) -> z , b(x, b(z, y)) -> f(b(f(f(z)), c(x, z, y))) } Obligation: innermost runtime complexity Answer: YES(?,O(1)) Arguments of following rules are not normal-forms: { b(x, b(z, y)) -> f(b(f(f(z)), c(x, z, y))) } All above mentioned rules can be savely removed. We are left with following problem, upon which TcT provides the certificate YES(?,O(1)). Strict Trs: { f(c(a(), z, x)) -> b(a(), z) , b(y, z) -> z } Obligation: innermost runtime complexity Answer: YES(?,O(1)) The input was oriented with the instance of 'Small Polynomial Path Order (PS,0-bounded)' as induced by the safe mapping safe(f) = {}, safe(c) = {1, 2, 3}, safe(a) = {}, safe(b) = {1, 2} and precedence f > b . Following symbols are considered recursive: {} The recursion depth is 0. For your convenience, here are the satisfied ordering constraints: f(c(; a(), z, x);) > b(; a(), z) b(; y, z) > z Hurray, we answered YES(?,O(1))