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