YES # Compositional parallel critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: F(H(x),y) -> G(H(x)) H(I(x)) -> I(x) F(I(x),y) -> G(I(x)) Let C be the following subset of R: (empty) The parallel critical pair system PCPS(R,C) is: F(H(I(x1_1)),y2) -> F(I(x1_1),y2) F(H(I(x1_1)),y2) -> G(H(I(x1_1))) 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.