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