YES # Compositional parallel critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: +(0(),x) -> x +(s(x),y) -> s(+(x,y)) Let C be the following subset of R: +(0(),x) -> x +(s(x),y) -> s(+(x,y)) The parallel critical pair system PCPS(R,C) is: (empty) The TRS R is locally confluent and PCPS(R,C)/R is terminating. Therefore, the confluence of R follows from that of C. # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: +(0(),x) -> x +(s(x),y) -> s(+(x,y)) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(+(0(),x) -> x) = 1 phi(+(s(x),y) -> s(+(x,y))) = 1 psi(+(0(),x) -> x) = 1 psi(+(s(x),y) -> s(+(x,y))) = 1