YES # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: c(c(x)) -> a(c(x)) c(b(x)) -> c(c(x)) b(a(x)) -> c(b(x)) a(b(x)) -> b(a(x)) c(a(x)) -> c(a(x)) b(c(x)) -> c(c(x)) c(c(x)) -> b(c(x)) c(a(x)) -> b(c(x)) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(c(c(x)) -> a(c(x))) = 8 phi(c(b(x)) -> c(c(x))) = 2 phi(b(a(x)) -> c(b(x))) = 7 phi(a(b(x)) -> b(a(x))) = 14 phi(c(a(x)) -> c(a(x))) = 1 phi(b(c(x)) -> c(c(x))) = 10 phi(c(c(x)) -> b(c(x))) = 13 phi(c(a(x)) -> b(c(x))) = 6 psi(c(c(x)) -> a(c(x))) = 12 psi(c(b(x)) -> c(c(x))) = 1 psi(b(a(x)) -> c(b(x))) = 4 psi(a(b(x)) -> b(a(x))) = 9 psi(c(a(x)) -> c(a(x))) = 2 psi(b(c(x)) -> c(c(x))) = 5 psi(c(c(x)) -> b(c(x))) = 11 psi(c(a(x)) -> b(c(x))) = 3