YES(?,POLY) We are left with following problem, upon which TcT provides the certificate YES(?,POLY). Strict Trs: { +(0(), y) -> y , +(s(x), y) -> s(+(x, y)) , -(x, 0()) -> x , -(0(), y) -> 0() , -(s(x), s(y)) -> -(x, y) } Obligation: innermost runtime complexity Answer: YES(?,POLY) The input was oriented with the instance of 'Polynomial Path Order' as induced by the safe mapping safe(+) = {2}, safe(0) = {}, safe(s) = {1}, safe(-) = {} and precedence + > - . Following symbols are considered recursive: {+, -} The recursion depth is 2. For your convenience, here are the satisfied ordering constraints: +(0(); y) > y +(s(; x); y) > s(; +(x; y)) -(x, 0();) > x -(0(), y;) > 0() -(s(; x), s(; y);) > -(x, y;) Hurray, we answered YES(?,POLY)