YES # Compositional parallel rule labeling (Shintani and Hirokawa 2022). Consider the left-linear TRS R: 0(1(2(3(4(x))))) -> 0(2(1(3(4(x))))) 0(5(1(2(4(3(x)))))) -> 0(5(2(1(4(3(x)))))) 0(5(2(4(1(3(x)))))) -> 0(1(5(2(4(3(x)))))) 0(5(3(1(2(4(x)))))) -> 0(1(5(3(2(4(x)))))) 0(5(4(1(3(2(x)))))) -> 0(5(4(3(1(2(x)))))) Let C be the following subset of R: (empty) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(0(1(2(3(4(x))))) -> 0(2(1(3(4(x)))))) = 1 phi(0(5(1(2(4(3(x)))))) -> 0(5(2(1(4(3(x))))))) = 1 phi(0(5(2(4(1(3(x)))))) -> 0(1(5(2(4(3(x))))))) = 1 phi(0(5(3(1(2(4(x)))))) -> 0(1(5(3(2(4(x))))))) = 1 phi(0(5(4(1(3(2(x)))))) -> 0(5(4(3(1(2(x))))))) = 1 psi(0(1(2(3(4(x))))) -> 0(2(1(3(4(x)))))) = 1 psi(0(5(1(2(4(3(x)))))) -> 0(5(2(1(4(3(x))))))) = 1 psi(0(5(2(4(1(3(x)))))) -> 0(1(5(2(4(3(x))))))) = 1 psi(0(5(3(1(2(4(x)))))) -> 0(1(5(3(2(4(x))))))) = 1 psi(0(5(4(1(3(2(x)))))) -> 0(5(4(3(1(2(x))))))) = 1 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.