We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict Trs: { is_empty(nil()) -> true() , is_empty(cons(x, l)) -> false() , hd(cons(x, l)) -> x , tl(cons(x, l)) -> l , append(l1, l2) -> ifappend(l1, l2, l1) , ifappend(l1, l2, nil()) -> l2 , ifappend(l1, l2, cons(x, l)) -> cons(x, append(l, l2)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We add the following weak dependency pairs: Strict DPs: { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , hd^#(cons(x, l)) -> c_3() , tl^#(cons(x, l)) -> c_4() , append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, nil()) -> c_6() , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } 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: { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , hd^#(cons(x, l)) -> c_3() , tl^#(cons(x, l)) -> c_4() , append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, nil()) -> c_6() , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Strict Trs: { is_empty(nil()) -> true() , is_empty(cons(x, l)) -> false() , hd(cons(x, l)) -> x , tl(cons(x, l)) -> l , append(l1, l2) -> ifappend(l1, l2, l1) , ifappend(l1, l2, nil()) -> l2 , ifappend(l1, l2, cons(x, l)) -> cons(x, append(l, l2)) } 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: { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , hd^#(cons(x, l)) -> c_3() , tl^#(cons(x, l)) -> c_4() , append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, nil()) -> c_6() , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } 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_5) = {1}, Uargs(c_7) = {1} TcT has computed the following constructor-restricted matrix interpretation. [nil] = [0] [0] [cons](x1, x2) = [1 0] x2 + [0] [0 0] [0] [is_empty^#](x1) = [0] [0] [c_1] = [0] [0] [c_2] = [0] [0] [hd^#](x1) = [1] [0] [c_3] = [0] [0] [tl^#](x1) = [0] [0] [c_4] = [0] [0] [append^#](x1, x2) = [0] [2] [c_5](x1) = [1 0] x1 + [0] [0 1] [0] [ifappend^#](x1, x2, x3) = [0 0] x1 + [0] [0 2] [0] [c_6] = [0] [0] [c_7](x1) = [1 0] x1 + [0] [0 1] [2] The order satisfies the following ordering constraints: [is_empty^#(nil())] = [0] [0] >= [0] [0] = [c_1()] [is_empty^#(cons(x, l))] = [0] [0] >= [0] [0] = [c_2()] [hd^#(cons(x, l))] = [1] [0] > [0] [0] = [c_3()] [tl^#(cons(x, l))] = [0] [0] >= [0] [0] = [c_4()] [append^#(l1, l2)] = [0] [2] ? [0 0] l1 + [0] [0 2] [0] = [c_5(ifappend^#(l1, l2, l1))] [ifappend^#(l1, l2, nil())] = [0 0] l1 + [0] [0 2] [0] >= [0] [0] = [c_6()] [ifappend^#(l1, l2, cons(x, l))] = [0 0] l1 + [0] [0 2] [0] ? [0] [4] = [c_7(append^#(l, l2))] 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(1),O(n^1)). Strict DPs: { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , tl^#(cons(x, l)) -> c_4() , append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, nil()) -> c_6() , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Weak DPs: { hd^#(cons(x, l)) -> c_3() } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We estimate the number of application of {1,2,3,5} by applications of Pre({1,2,3,5}) = {4}. Here rules are labeled as follows: DPs: { 1: is_empty^#(nil()) -> c_1() , 2: is_empty^#(cons(x, l)) -> c_2() , 3: tl^#(cons(x, l)) -> c_4() , 4: append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , 5: ifappend^#(l1, l2, nil()) -> c_6() , 6: ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) , 7: hd^#(cons(x, l)) -> c_3() } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Weak DPs: { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , hd^#(cons(x, l)) -> c_3() , tl^#(cons(x, l)) -> c_4() , ifappend^#(l1, l2, nil()) -> c_6() } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed. { is_empty^#(nil()) -> c_1() , is_empty^#(cons(x, l)) -> c_2() , hd^#(cons(x, l)) -> c_3() , tl^#(cons(x, l)) -> c_4() , ifappend^#(l1, l2, nil()) -> c_6() } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We use the processor 'matrix interpretation of dimension 1' to orient following rules strictly. DPs: { 1: append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , 2: ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Sub-proof: ---------- The following argument positions are usable: Uargs(c_5) = {1}, Uargs(c_7) = {1} TcT has computed the following constructor-based matrix interpretation satisfying not(EDA). [cons](x1, x2) = [1] x2 + [2] [append^#](x1, x2) = [4] x1 + [4] [c_5](x1) = [1] x1 + [1] [ifappend^#](x1, x2, x3) = [4] x3 + [0] [c_7](x1) = [1] x1 + [0] The order satisfies the following ordering constraints: [append^#(l1, l2)] = [4] l1 + [4] > [4] l1 + [1] = [c_5(ifappend^#(l1, l2, l1))] [ifappend^#(l1, l2, cons(x, l))] = [4] l + [8] > [4] l + [4] = [c_7(append^#(l, l2))] The strictly oriented rules are moved into the weak component. We are left with following problem, upon which TcT provides the certificate YES(O(1),O(1)). Weak DPs: { append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(1)) The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed. { append^#(l1, l2) -> c_5(ifappend^#(l1, l2, l1)) , ifappend^#(l1, l2, cons(x, l)) -> c_7(append^#(l, l2)) } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(1)). Rules: Empty Obligation: innermost runtime complexity Answer: YES(O(1),O(1)) Empty rules are trivially bounded Hurray, we answered YES(O(1),O(n^1))