YES # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: b(a(a(b(b(x))))) -> b(a(a(a(a(b(b(x))))))) b(a(b(b(x)))) -> b(b(x)) b(a(b(a(a(a(a(b(x)))))))) -> b(a(a(a(a(b(a(a(a(a(b(a(b(a(a(a(b(a(a(a(a(b(x)))))))))))))))))))))) b(a(a(b(a(a(a(a(b(x))))))))) -> b(a(b(a(a(b(a(a(a(b(a(a(a(a(b(x))))))))))))))) b(a(a(a(b(a(a(a(a(b(x)))))))))) -> b(x) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(b(a(a(b(b(x))))) -> b(a(a(a(a(b(b(x)))))))) = 1 phi(b(a(b(b(x)))) -> b(b(x))) = 1 phi(b(a(b(a(a(a(a(b(x)))))))) -> b(a(a(a(a(b(a(a(a(a(b(a(b(a(a(a(b(a(a(a(a(b(x))))))))))))))))))))))) = 1 phi(b(a(a(b(a(a(a(a(b(x))))))))) -> b(a(b(a(a(b(a(a(a(b(a(a(a(a(b(x)))))))))))))))) = 1 phi(b(a(a(a(b(a(a(a(a(b(x)))))))))) -> b(x)) = 1 psi(b(a(a(b(b(x))))) -> b(a(a(a(a(b(b(x)))))))) = 1 psi(b(a(b(b(x)))) -> b(b(x))) = 1 psi(b(a(b(a(a(a(a(b(x)))))))) -> b(a(a(a(a(b(a(a(a(a(b(a(b(a(a(a(b(a(a(a(a(b(x))))))))))))))))))))))) = 1 psi(b(a(a(b(a(a(a(a(b(x))))))))) -> b(a(b(a(a(b(a(a(a(b(a(a(a(a(b(x)))))))))))))))) = 1 psi(b(a(a(a(b(a(a(a(a(b(x)))))))))) -> b(x)) = 1