YES O(n^4) TRS: { g(h2(x, y, h1(z, u))) -> h2(s(x), y, h1(z, u)), f(x, h1(y, z)) -> h2(0(), x, h1(y, z)), f(j(x, y), y) -> g(f(x, k(y))), k(h1(x, y)) -> h1(s(x), y), k(h(x)) -> h1(0(), x), h2(x, j(y, h1(z, u)), h1(z, u)) -> h2(s(x), y, h1(s(z), u)), i(f(x, h(y))) -> y, i(h2(s(x), y, h1(x, z))) -> z } DUP: We consider a non-duplicating system. Trs: { g(h2(x, y, h1(z, u))) -> h2(s(x), y, h1(z, u)), f(x, h1(y, z)) -> h2(0(), x, h1(y, z)), f(j(x, y), y) -> g(f(x, k(y))), k(h1(x, y)) -> h1(s(x), y), k(h(x)) -> h1(0(), x), h2(x, j(y, h1(z, u)), h1(z, u)) -> h2(s(x), y, h1(s(z), u)), i(f(x, h(y))) -> y, i(h2(s(x), y, h1(x, z))) -> z } Matrix Interpretation: Interpretation class: triangular [X3] [1 1 1 0][X3] [0] [X2] [0 1 0 0][X2] [1] [h]([X1]) = [0 0 1 0][X1] + [1] [X0] [0 0 0 1][X0] [0] [X3] [1 0 0 0][X3] [1] [X2] [0 1 0 0][X2] [0] [i]([X1]) = [0 0 1 0][X1] + [0] [X0] [0 0 0 1][X0] [0] [X3] [1 0 0 0][X3] [0] [X2] [0 0 0 0][X2] [0] [s]([X1]) = [0 0 0 0][X1] + [0] [X0] [0 0 0 0][X0] [0] [X7] [X3] [1 0 0 0][X7] [1 1 0 0][X3] [0] [X6] [X2] [0 0 0 0][X6] [0 1 0 0][X2] [1] [h1]([X5], [X1]) = [0 0 0 0][X5] + [0 0 1 0][X1] + [1] [X4] [X0] [0 0 0 0][X4] [0 0 0 1][X0] [0] [0] [0] [0] = [0] [0] [X11] [X7] [X3] [1 0 0 0][X11] [1 0 0 0][X7] [1 0 0 0][X3] [0] [X10] [X6] [X2] [0 0 0 0][X10] [0 0 0 0][X6] [0 1 0 0][X2] [0] [h2]([ X9], [X5], [X1]) = [0 0 0 0][X9] + [0 0 0 0][X5] + [0 0 1 0][X1] + [0] [ X8] [X4] [X0] [0 0 0 1][X8] [0 0 0 0][X4] [0 0 0 1][X0] [0] [X7] [X3] [1 0 0 0][X7] [1 1 1 0][X3] [1] [X6] [X2] [0 1 0 0][X6] [0 0 1 0][X2] [0] [j]([X5], [X1]) = [0 0 1 0][X5] + [0 0 1 0][X1] + [0] [X4] [X0] [0 0 0 0][X4] [0 0 0 0][X0] [0] [X3] [1 0 1 0][X3] [0] [X2] [0 1 1 0][X2] [0] [k]([X1]) = [0 0 1 0][X1] + [0] [X0] [0 0 0 1][X0] [0] [X7] [X3] [1 1 1 0][X7] [1 1 0 0][X3] [0] [X6] [X2] [0 0 1 0][X6] [0 1 0 0][X2] [0] [f]([X5], [X1]) = [0 0 0 0][X5] + [0 0 1 0][X1] + [0] [X4] [X0] [0 0 0 0][X4] [0 0 0 1][X0] [0] [X3] [1 0 1 0][X3] [0] [X2] [0 1 0 0][X2] [0] [g]([X1]) = [0 0 1 0][X1] + [0] [X0] [0 0 0 1][X0] [0] Qed