YES # Compositional parallel critical pair system (Shintani and Hirokawa 2022). Consider the left-linear TRS R: F(H(x),y) -> F(H(x),I(I(y))) F(x,G(y)) -> F(I(x),G(y)) I(x) -> x Let C be the following subset of R: F(H(x),y) -> F(H(x),I(I(y))) F(x,G(y)) -> F(I(x),G(y)) I(x) -> x 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. # Parallel rule labeling (Zankl et al. 2015). Consider the left-linear TRS R: F(H(x),y) -> F(H(x),I(I(y))) F(x,G(y)) -> F(I(x),G(y)) I(x) -> x All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(F(H(x),y) -> F(H(x),I(I(y)))) = 2 phi(F(x,G(y)) -> F(I(x),G(y))) = 3 phi(I(x) -> x) = 1 psi(F(H(x),y) -> F(H(x),I(I(y)))) = 2 psi(F(x,G(y)) -> F(I(x),G(y))) = 3 psi(I(x) -> x) = 1