YES(?,POLY) 'Pop* (timeout of 60.0 seconds)' -------------------------------- Answer: YES(?,POLY) Input Problem: innermost runtime-complexity with respect to Rules: { not(true()) -> false() , not(false()) -> true() , odd(0()) -> false() , odd(s(x)) -> not(odd(x)) , +(x, 0()) -> x , +(x, s(y)) -> s(+(x, y)) , +(s(x), y) -> s(+(x, y))} Proof Output: The input was oriented with the instance of POP* as induced by the precedence odd > not, + > not, odd ~ + and safe mapping safe(not) = {1}, safe(true) = {}, safe(false) = {}, safe(odd) = {}, safe(0) = {}, safe(s) = {1}, safe(+) = {} . For your convenience, here is the input in predicative notation: Rules: { not(; true()) -> false() , not(; false()) -> true() , odd(0();) -> false() , odd(s(; x);) -> not(; odd(x;)) , +(x, 0();) -> x , +(x, s(; y);) -> s(; +(x, y;)) , +(s(; x), y;) -> s(; +(x, y;))}