YES # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: f(f(x,y),z) -> f(x,f(y,z)) f(x,y) -> f(y,x) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(f(f(x,y),z) -> f(x,f(y,z))) = 3 phi(f(x,y) -> f(y,x)) = 2 psi(f(f(x,y),z) -> f(x,f(y,z))) = 1 psi(f(x,y) -> f(y,x)) = 1