YES # Compositional parallel rule labeling (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) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(-(+(x(),-(x()))) -> 0()) = 3 phi(+(x(),-(x())) -> 0()) = 1 phi(0() -> -(0())) = 2 psi(-(+(x(),-(x()))) -> 0()) = 3 psi(+(x(),-(x())) -> 0()) = 1 psi(0() -> -(0())) = 2 Therefore, the confluence of R follows from that of C. # Compositional parallel critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: (empty) 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.