YES(O(1),O(n^1)) We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict Trs: { p(0()) -> 0() , p(s(x)) -> x , minus(x, 0()) -> x , minus(x, s(y)) -> minus(p(x), y) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We use the processor 'Small Polynomial Path Order (PS,1-bounded)' to orient following rules strictly. Trs: { p(0()) -> 0() , p(s(x)) -> x , minus(x, 0()) -> x , minus(x, s(y)) -> minus(p(x), y) } The induced complexity on above rules (modulo remaining rules) is YES(?,O(n^1)) . These rules are moved into the corresponding weak component(s). Sub-proof: ---------- The input was oriented with the instance of 'Small Polynomial Path Order (PS,1-bounded)' as induced by the safe mapping safe(p) = {1}, safe(0) = {}, safe(s) = {1}, safe(minus) = {1} and precedence minus > p . Following symbols are considered recursive: {minus} The recursion depth is 1. For your convenience, here are the satisfied ordering constraints: p(; 0()) > 0() p(; s(; x)) > x minus(0(); x) > x minus(s(; y); x) > minus(y; p(; x)) We return to the main proof. We are left with following problem, upon which TcT provides the certificate YES(O(1),O(1)). Weak Trs: { p(0()) -> 0() , p(s(x)) -> x , minus(x, 0()) -> x , minus(x, s(y)) -> minus(p(x), y) } Obligation: innermost runtime complexity Answer: YES(O(1),O(1)) Empty rules are trivially bounded Hurray, we answered YES(O(1),O(n^1))