YES O(n^2) TRS: {a(b(a(x))) -> b(a(x))} Natural interpretation: Strict: {a(b(a(x))) -> b(a(x))} Weak: {} Interpretation class: deltarestricted [a](delta, X0) = + 0*X0 + 1 + 1*X0*delta + 0*delta [b](delta, X0) = + 1*X0 + 0 + 0*X0*delta + 0*delta a_tau_1(delta) = delta/(0 + 1 * delta) b_tau_1(delta) = delta/(1 + 0 * delta) Qed