YES O(n^2) TRS: {f(s(X), Y) -> h(s(f(h(Y), X)))} Natural interpretation: Strict: {f(s(X), Y) -> h(s(f(h(Y), X)))} Weak: {} Interpretation class: deltarestricted [f](delta, X1, X0) = + 1*X0 + 1*X1 + 0 + 1*X0*delta + 1*X1*delta + 0*delta [s](delta, X0) = + 1*X0 + 1 + 0*X0*delta + 0*delta [h](delta, X0) = + 1*X0 + 0 + 0*X0*delta + 0*delta f_tau_1(delta) = delta/(1 + 1 * delta)f_tau_2(delta) = delta/(1 + 1 * delta) s_tau_1(delta) = delta/(1 + 0 * delta) h_tau_1(delta) = delta/(1 + 0 * delta) Qed