We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We add the following dependency tuples: Strict DPs: { flatten^#(flatten(x)) -> c_1(flatten^#(x)) , flatten^#(nil()) -> c_2() , flatten^#(unit(x)) -> c_3(flatten^#(x)) , flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(x, nil()) -> c_6() , ++^#(nil(), y) -> c_7() , ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) , rev^#(nil()) -> c_9() , rev^#(unit(x)) -> c_10() , rev^#(++(x, y)) -> c_11(++^#(rev(y), rev(x)), rev^#(y), rev^#(x)) , rev^#(rev(x)) -> c_12() } 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: { flatten^#(flatten(x)) -> c_1(flatten^#(x)) , flatten^#(nil()) -> c_2() , flatten^#(unit(x)) -> c_3(flatten^#(x)) , flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(x, nil()) -> c_6() , ++^#(nil(), y) -> c_7() , ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) , rev^#(nil()) -> c_9() , rev^#(unit(x)) -> c_10() , rev^#(++(x, y)) -> c_11(++^#(rev(y), rev(x)), rev^#(y), rev^#(x)) , rev^#(rev(x)) -> c_12() } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) Consider the dependency graph: 1: flatten^#(flatten(x)) -> c_1(flatten^#(x)) 2: flatten^#(nil()) -> c_2() 3: flatten^#(unit(x)) -> c_3(flatten^#(x)) -->_1 flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :5 -->_1 flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :4 -->_1 flatten^#(unit(x)) -> c_3(flatten^#(x)) :3 -->_1 flatten^#(nil()) -> c_2() :2 -->_1 flatten^#(flatten(x)) -> c_1(flatten^#(x)) :1 4: flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) -->_1 ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) :8 -->_3 flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :5 -->_1 ++^#(nil(), y) -> c_7() :7 -->_1 ++^#(x, nil()) -> c_6() :6 -->_3 flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :4 -->_3 flatten^#(unit(x)) -> c_3(flatten^#(x)) :3 -->_2 flatten^#(unit(x)) -> c_3(flatten^#(x)) :3 -->_3 flatten^#(flatten(x)) -> c_1(flatten^#(x)) :1 -->_2 flatten^#(flatten(x)) -> c_1(flatten^#(x)) :1 5: flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) -->_1 ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) :8 -->_1 ++^#(nil(), y) -> c_7() :7 -->_1 ++^#(x, nil()) -> c_6() :6 -->_3 flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :5 -->_2 flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :5 -->_3 flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :4 -->_2 flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) :4 -->_3 flatten^#(unit(x)) -> c_3(flatten^#(x)) :3 -->_2 flatten^#(unit(x)) -> c_3(flatten^#(x)) :3 -->_2 flatten^#(nil()) -> c_2() :2 -->_3 flatten^#(flatten(x)) -> c_1(flatten^#(x)) :1 -->_2 flatten^#(flatten(x)) -> c_1(flatten^#(x)) :1 6: ++^#(x, nil()) -> c_6() 7: ++^#(nil(), y) -> c_7() 8: ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) -->_2 ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) :8 -->_2 ++^#(x, nil()) -> c_6() :6 -->_1 ++^#(x, nil()) -> c_6() :6 9: rev^#(nil()) -> c_9() 10: rev^#(unit(x)) -> c_10() 11: rev^#(++(x, y)) -> c_11(++^#(rev(y), rev(x)), rev^#(y), rev^#(x)) -->_3 rev^#(rev(x)) -> c_12() :12 -->_2 rev^#(rev(x)) -> c_12() :12 -->_2 rev^#(++(x, y)) -> c_11(++^#(rev(y), rev(x)), rev^#(y), rev^#(x)) :11 -->_3 rev^#(unit(x)) -> c_10() :10 -->_2 rev^#(unit(x)) -> c_10() :10 -->_1 ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) :8 -->_1 ++^#(nil(), y) -> c_7() :7 -->_1 ++^#(x, nil()) -> c_6() :6 12: rev^#(rev(x)) -> c_12() Only the nodes {2,3,5,8,6,7,4,1,9,10} are reachable from nodes {2,3,6,7,9,10} that start derivation from marked basic terms. The nodes not reachable are removed from the problem. We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(flatten(x)) -> c_1(flatten^#(x)) , flatten^#(nil()) -> c_2() , flatten^#(unit(x)) -> c_3(flatten^#(x)) , flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(x, nil()) -> c_6() , ++^#(nil(), y) -> c_7() , ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) , rev^#(nil()) -> c_9() , rev^#(unit(x)) -> c_10() } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We estimate the number of application of {1,2,6,7,9,10} by applications of Pre({1,2,6,7,9,10}) = {3,4,5,8}. Here rules are labeled as follows: DPs: { 1: flatten^#(flatten(x)) -> c_1(flatten^#(x)) , 2: flatten^#(nil()) -> c_2() , 3: flatten^#(unit(x)) -> c_3(flatten^#(x)) , 4: flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , 5: flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , 6: ++^#(x, nil()) -> c_6() , 7: ++^#(nil(), y) -> c_7() , 8: ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) , 9: rev^#(nil()) -> c_9() , 10: rev^#(unit(x)) -> c_10() } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_3(flatten^#(x)) , flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) } Weak DPs: { flatten^#(flatten(x)) -> c_1(flatten^#(x)) , flatten^#(nil()) -> c_2() , ++^#(x, nil()) -> c_6() , ++^#(nil(), y) -> c_7() , rev^#(nil()) -> c_9() , rev^#(unit(x)) -> c_10() } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } 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. { flatten^#(flatten(x)) -> c_1(flatten^#(x)) , flatten^#(nil()) -> c_2() , ++^#(x, nil()) -> c_6() , ++^#(nil(), y) -> c_7() , rev^#(nil()) -> c_9() , rev^#(unit(x)) -> c_10() } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_3(flatten^#(x)) , flatten^#(++(x, y)) -> c_4(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_5(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) Due to missing edges in the dependency-graph, the right-hand sides of following rules could be simplified: { ++^#(++(x, y), z) -> c_8(++^#(x, ++(y, z)), ++^#(y, z)) } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(++(x, y), z) -> c_4(++^#(y, z)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) , rev(nil()) -> nil() , rev(unit(x)) -> unit(x) , rev(++(x, y)) -> ++(rev(y), rev(x)) , rev(rev(x)) -> x } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) We replace rewrite rules by usable rules: Weak Usable Rules: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , ++^#(++(x, y), z) -> c_4(++^#(y, z)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } 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: { 4: ++^#(++(x, y), z) -> c_4(++^#(y, z)) } Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } Sub-proof: ---------- The following argument positions are usable: Uargs(c_1) = {1}, Uargs(c_2) = {1, 2, 3}, Uargs(c_3) = {1, 2, 3}, Uargs(c_4) = {1} TcT has computed the following constructor-based matrix interpretation satisfying not(EDA). [flatten](x1) = [3] x1 + [2] [nil] = [0] [unit](x1) = [1] x1 + [0] [++](x1, x2) = [3] x1 + [1] x2 + [3] [flatten^#](x1) = [4] x1 + [2] [++^#](x1, x2) = [2] x1 + [6] [c_1](x1) = [1] x1 + [0] [c_2](x1, x2, x3) = [1] x1 + [1] x2 + [1] x3 + [0] [c_3](x1, x2, x3) = [1] x1 + [1] x2 + [1] x3 + [0] [c_4](x1) = [1] x1 + [1] The order satisfies the following ordering constraints: [flatten(flatten(x))] = [9] x + [8] > [3] x + [2] = [flatten(x)] [flatten(nil())] = [2] > [0] = [nil()] [flatten(unit(x))] = [3] x + [2] >= [3] x + [2] = [flatten(x)] [flatten(++(x, y))] = [9] x + [3] y + [11] >= [9] x + [3] y + [11] = [++(flatten(x), flatten(y))] [flatten(++(unit(x), y))] = [9] x + [3] y + [11] >= [9] x + [3] y + [11] = [++(flatten(x), flatten(y))] [++(x, nil())] = [3] x + [3] > [1] x + [0] = [x] [++(nil(), y)] = [1] y + [3] > [1] y + [0] = [y] [++(++(x, y), z)] = [9] x + [3] y + [1] z + [12] > [3] x + [3] y + [1] z + [6] = [++(x, ++(y, z))] [flatten^#(unit(x))] = [4] x + [2] >= [4] x + [2] = [c_1(flatten^#(x))] [flatten^#(++(x, y))] = [12] x + [4] y + [14] >= [10] x + [4] y + [14] = [c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y))] [flatten^#(++(unit(x), y))] = [12] x + [4] y + [14] >= [10] x + [4] y + [14] = [c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y))] [++^#(++(x, y), z)] = [6] x + [2] y + [12] > [2] y + [7] = [c_4(++^#(y, z))] 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(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) } Weak DPs: { ++^#(++(x, y), z) -> c_4(++^#(y, z)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } 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. { ++^#(++(x, y), z) -> c_4(++^#(y, z)) } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } Obligation: innermost runtime complexity Answer: YES(O(1),O(n^1)) Due to missing edges in the dependency-graph, the right-hand sides of following rules could be simplified: { flatten^#(++(x, y)) -> c_2(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(++^#(flatten(x), flatten(y)), flatten^#(x), flatten^#(y)) } We are left with following problem, upon which TcT provides the certificate YES(O(1),O(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } Weak Trs: { flatten(flatten(x)) -> flatten(x) , flatten(nil()) -> nil() , flatten(unit(x)) -> flatten(x) , flatten(++(x, y)) -> ++(flatten(x), flatten(y)) , flatten(++(unit(x), y)) -> ++(flatten(x), flatten(y)) , ++(x, nil()) -> x , ++(nil(), y) -> y , ++(++(x, y), z) -> ++(x, ++(y, z)) } 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: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } 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: { 2: flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , 3: flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } Sub-proof: ---------- The following argument positions are usable: Uargs(c_1) = {1}, Uargs(c_2) = {1, 2}, Uargs(c_3) = {1, 2} TcT has computed the following constructor-based matrix interpretation satisfying not(EDA). [flatten](x1) = [0] [nil] = [0] [unit](x1) = [1] x1 + [0] [++](x1, x2) = [4] x1 + [4] x2 + [4] [flatten^#](x1) = [2] x1 + [0] [++^#](x1, x2) = [0] [c_1](x1) = [0] [c_2](x1, x2, x3) = [0] [c_3](x1, x2, x3) = [0] [c_4](x1) = [0] [c] = [0] [c_1](x1) = [1] x1 + [0] [c_2](x1, x2) = [4] x1 + [4] x2 + [0] [c_3](x1, x2) = [1] x1 + [1] x2 + [1] The order satisfies the following ordering constraints: [flatten^#(unit(x))] = [2] x + [0] >= [2] x + [0] = [c_1(flatten^#(x))] [flatten^#(++(x, y))] = [8] x + [8] y + [8] > [8] x + [8] y + [0] = [c_2(flatten^#(x), flatten^#(y))] [flatten^#(++(unit(x), y))] = [8] x + [8] y + [8] > [2] x + [2] y + [1] = [c_3(flatten^#(x), flatten^#(y))] 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(n^1)). Strict DPs: { flatten^#(unit(x)) -> c_1(flatten^#(x)) } Weak DPs: { flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } 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: flatten^#(unit(x)) -> c_1(flatten^#(x)) , 3: flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } Sub-proof: ---------- The following argument positions are usable: Uargs(c_1) = {1}, Uargs(c_2) = {1, 2}, Uargs(c_3) = {1, 2} TcT has computed the following constructor-based matrix interpretation satisfying not(EDA). [flatten](x1) = [0] [nil] = [0] [unit](x1) = [1] x1 + [2] [++](x1, x2) = [1] x1 + [2] x2 + [2] [flatten^#](x1) = [3] x1 + [3] [++^#](x1, x2) = [0] [c_1](x1) = [0] [c_2](x1, x2, x3) = [0] [c_3](x1, x2, x3) = [0] [c_4](x1) = [0] [c] = [0] [c_1](x1) = [1] x1 + [4] [c_2](x1, x2) = [1] x1 + [2] x2 + [0] [c_3](x1, x2) = [1] x1 + [1] x2 + [4] The order satisfies the following ordering constraints: [flatten^#(unit(x))] = [3] x + [9] > [3] x + [7] = [c_1(flatten^#(x))] [flatten^#(++(x, y))] = [3] x + [6] y + [9] >= [3] x + [6] y + [9] = [c_2(flatten^#(x), flatten^#(y))] [flatten^#(++(unit(x), y))] = [3] x + [6] y + [15] > [3] x + [3] y + [10] = [c_3(flatten^#(x), flatten^#(y))] 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: { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } 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. { flatten^#(unit(x)) -> c_1(flatten^#(x)) , flatten^#(++(x, y)) -> c_2(flatten^#(x), flatten^#(y)) , flatten^#(++(unit(x), y)) -> c_3(flatten^#(x), flatten^#(y)) } 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))