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)) +(0(),y) -> y +(p(x),y) -> p(+(x,y)) +(s(x),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))) +(s(p(x0)),y1) -> +(x0,y1) +(s(p(x0)),y1) -> s(+(p(x0),y1)) s(p(s(x0))) -> s(x0) +(y0,p(s(x0))) -> +(y0,x0) +(y0,p(s(x0))) -> p(+(y0,s(x0))) +(p(s(x0)),y1) -> +(x0,y1) +(p(s(x0)),y1) -> p(+(s(x0),y1)) +(0(),0()) -> 0() +(p(y0),0()) -> p(y0) +(p(y0),0()) -> p(+(y0,0())) +(s(y0),0()) -> s(y0) +(s(y0),0()) -> s(+(y0,0())) +(0(),s(x1)) -> s(+(0(),x1)) +(0(),s(x1)) -> s(x1) +(p(y0),s(x1)) -> s(+(p(y0),x1)) +(p(y0),s(x1)) -> p(+(y0,s(x1))) +(s(y0),s(x1)) -> s(+(s(y0),x1)) +(s(y0),s(x1)) -> s(+(y0,s(x1))) +(0(),p(x1)) -> p(+(0(),x1)) +(0(),p(x1)) -> p(x1) +(p(y0),p(x1)) -> p(+(p(y0),x1)) +(p(y0),p(x1)) -> p(+(y0,p(x1))) +(s(y0),p(x1)) -> p(+(s(y0),x1)) +(s(y0),p(x1)) -> s(+(y0,p(x1))) +(0(),s(y1)) -> s(y1) +(0(),s(y1)) -> s(+(0(),y1)) +(0(),p(y1)) -> p(y1) +(0(),p(y1)) -> p(+(0(),y1)) +(p(x0),0()) -> p(+(x0,0())) +(p(x0),0()) -> p(x0) +(p(x0),s(y1)) -> p(+(x0,s(y1))) +(p(x0),s(y1)) -> s(+(p(x0),y1)) +(p(x0),p(y1)) -> p(+(x0,p(y1))) +(p(x0),p(y1)) -> p(+(p(x0),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(x0),p(y1)) -> s(+(x0,p(y1))) +(s(x0),p(y1)) -> p(+(s(x0),y1)) The TRS R is locally confluent and CPS(R,C)/R is terminating. Therefore, the confluence of R follows from that of C. # Emptiness. The empty TRS is confluent.