YES(?,O(n^1)) TRS: { f(x, h1(y, z)) -> h2(0(), x, h1(y, z)), f(j(x, y), y) -> g f(x, k y), g h2(x, y, h1(z, u)) -> h2(s x, y, h1(z, u)), k h x -> h1(0(), x), k h1(x, y) -> h1(s x, y), 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: { f(x, h1(y, z)) -> h2(0(), x, h1(y, z)), f(j(x, y), y) -> g f(x, k y), g h2(x, y, h1(z, u)) -> h2(s x, y, h1(z, u)), k h x -> h1(0(), x), k h1(x, y) -> h1(s x, y), 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 } Natural interpretation: Strict: { f(x, h1(y, z)) -> h2(0(), x, h1(y, z)), f(j(x, y), y) -> g f(x, k y), g h2(x, y, h1(z, u)) -> h2(s x, y, h1(z, u)), k h x -> h1(0(), x), k h1(x, y) -> h1(s x, y), 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 } Weak: {} Interpretation class: stronglylinear [i](X0) = + 1*X0 + 7 [s](X0) = + 1*X0 + 0 [h1](X1, X0) = + 1*X0 + 1*X1 + 1 [0] = + 0 [h2](X2, X1, X0) = + 1*X0 + 1*X1 + 1*X2 + 0 [j](X1, X0) = + 1*X0 + 1*X1 + 7 [k](X0) = + 1*X0 + 1 [h](X0) = + 1*X0 + 6 [g](X0) = + 1*X0 + 1 [f](X1, X0) = + 1*X0 + 1*X1 + 2 Qed