YES # Compositional critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: s(p(x)) -> x p(s(x)) -> x +(x,0()) -> x +(x,s(y)) -> s(+(x,y)) +(x,p(y)) -> p(+(x,y)) -(x,0()) -> x -(x,s(y)) -> p(-(x,y)) -(x,p(y)) -> s(-(x,y)) Let C be the following subset of R: (empty) The critical pair system CPS(R,C) is: p(s(p(x0))) -> p(x0) +(y0,s(p(x0))) -> +(y0,x0) +(y0,s(p(x0))) -> s(+(y0,p(x0))) -(y0,s(p(x0))) -> -(y0,x0) -(y0,s(p(x0))) -> p(-(y0,p(x0))) s(p(s(x0))) -> s(x0) +(y0,p(s(x0))) -> +(y0,x0) +(y0,p(s(x0))) -> p(+(y0,s(x0))) -(y0,p(s(x0))) -> -(y0,x0) -(y0,p(s(x0))) -> s(-(y0,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.