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