YES # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: nats() -> :(0(),inc(nats())) inc(:(x,y)) -> :(s(x),inc(y)) inc(tl(nats())) -> tl(inc(nats())) hd(:(x,y)) -> x tl(:(x,y)) -> y d(:(x,y)) -> :(x,:(x,d(y))) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(nats() -> :(0(),inc(nats()))) = 2 phi(inc(:(x,y)) -> :(s(x),inc(y))) = 1 phi(inc(tl(nats())) -> tl(inc(nats()))) = 4 phi(hd(:(x,y)) -> x) = 1 phi(tl(:(x,y)) -> y) = 1 phi(d(:(x,y)) -> :(x,:(x,d(y)))) = 1 psi(nats() -> :(0(),inc(nats()))) = 3 psi(inc(:(x,y)) -> :(s(x),inc(y))) = 1 psi(inc(tl(nats())) -> tl(inc(nats()))) = 4 psi(hd(:(x,y)) -> x) = 1 psi(tl(:(x,y)) -> y) = 1 psi(d(:(x,y)) -> :(x,:(x,d(y)))) = 1