YES(?,POLY) 'Pop* with parameter subtitution (timeout of 60.0 seconds)' ----------------------------------------------------------- Answer: YES(?,POLY) Input Problem: innermost runtime-complexity with respect to Rules: { f(x, a()) -> x , f(x, g(y)) -> f(g(x), y)} Proof Output: The input was oriented with the instance of POP* as induced by the precedence empty and safe mapping safe(f) = {1}, safe(a) = {}, safe(g) = {1} . For your convenience, here is the input in predicative notation: Rules: { f(a(); x) -> x , f(g(; y); x) -> f(y; g(; x))}