YES # Compositional critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: +(0(),y) -> y +(s(x),y) -> s(+(x,y)) s(s(x)) -> x Let C be the following subset of R: (empty) The critical pair system CPS(R,C) is: +(s(s(x0)),y1) -> +(x0,y1) +(s(s(x0)),y1) -> s(+(s(x0),y1)) s(s(s(x0))) -> s(x0) All pairs in PCP(R) are joinable and PCPS(R,C)/R is terminating. Therefore, the confluence of R follows from that of C. # emptiness The empty TRS is confluent.