YES # Compositional critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: F(c(x)) -> G(x) G(x) -> F(x) c(x) -> x Let C be the following subset of R: (empty) The critical pair system CPS(R,C) is: F(c(y0)) -> F(y0) F(c(y0)) -> G(y0) 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.