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