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: { app(nil(), xs) -> nil() , app(cons(x, xs), ys) -> cons(x, app(xs, ys)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We add following weak dependency pairs: Strict DPs: { app^#(nil(), xs) -> c_1() , app^#(cons(x, xs), ys) -> c_2(app^#(xs, ys)) } and mark the set of starting terms. We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { app^#(nil(), xs) -> c_1() , app^#(cons(x, xs), ys) -> c_2(app^#(xs, ys)) } Strict Trs: { app(nil(), xs) -> nil() , app(cons(x, xs), ys) -> cons(x, app(xs, ys)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) No rule is usable, rules are removed from the input problem. We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { app^#(nil(), xs) -> c_1() , app^#(cons(x, xs), ys) -> c_2(app^#(xs, ys)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) The weightgap principle applies (using the following constant growth matrix-interpretation) The following argument positions are usable: Uargs(c_2) = {1} TcT has computed following constructor-restricted matrix interpretation. [nil] = [2] [cons](x1, x2) = [1] x2 + [1] [app^#](x1, x2) = [2] x2 + [1] [c_1] = [0] [c_2](x1) = [1] x1 + [0] This order satisfies following ordering constraints: Further, it can be verified that all rules not oriented are covered by the weightgap condition. We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict DPs: { app^#(cons(x, xs), ys) -> c_2(app^#(xs, ys)) } Weak DPs: { app^#(nil(), xs) -> c_1() } Obligation: innermost runtime complexity Answer: YES(?,O(n^1)) The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed. { app^#(nil(), xs) -> c_1() } We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict DPs: { app^#(cons(x, xs), ys) -> c_2(app^#(xs, ys)) } Obligation: innermost runtime complexity Answer: YES(?,O(n^1)) The input was oriented with the instance of 'Small Polynomial Path Order (PS)' as induced by the safe mapping safe(cons) = {1, 2}, safe(app^#) = {2}, safe(c_2) = {} and precedence empty . Following symbols are considered recursive: {app^#} The recursion depth is 1. Further, following argument filtering is employed: pi(cons) = [1, 2], pi(app^#) = [1, 2], pi(c_2) = [1] Usable defined function symbols are a subset of: {app^#} For your convenience, here are the satisfied ordering constraints: pi(app^#(cons(x, xs), ys)) = app^#(cons(; x, xs); ys) > c_2(app^#(xs; ys);) = pi(c_2(app^#(xs, ys))) Hurray, we answered YES(O(1),O(n^1))