YES # Compositional critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: +(0(),y) -> y +(s(x),y) -> s(+(x,y)) +(x,0()) -> x +(x,s(y)) -> s(+(x,y)) Let C be the following subset of R: (empty) The critical pair system CPS(R,C) is: +(0(),0()) -> 0() +(0(),s(y1)) -> s(y1) +(0(),s(y1)) -> s(+(0(),y1)) +(s(x0),0()) -> s(+(x0,0())) +(s(x0),0()) -> s(x0) +(s(x0),s(y1)) -> s(+(x0,s(y1))) +(s(x0),s(y1)) -> s(+(s(x0),y1)) +(s(y0),0()) -> s(y0) +(s(y0),0()) -> s(+(y0,0())) +(0(),s(x1)) -> s(+(0(),x1)) +(0(),s(x1)) -> s(x1) +(s(y0),s(x1)) -> s(+(s(y0),x1)) +(s(y0),s(x1)) -> s(+(y0,s(x1))) 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.