YES # Compositional parallel rule labeling (Shintani and Hirokawa 2022). Consider the left-linear TRS R: -(0(),0()) -> 0() -(s(x),0()) -> s(x) -(x,s(y)) -> -(d(x),y) d(s(x)) -> x -(s(x),s(y)) -> -(x,y) -(d(x),y) -> -(x,s(y)) Let C be the following subset of R: (empty) All parallel critical peaks (except C's) are decreasing wrt rule labeling: phi(-(0(),0()) -> 0()) = 1 phi(-(s(x),0()) -> s(x)) = 1 phi(-(x,s(y)) -> -(d(x),y)) = 1 phi(d(s(x)) -> x) = 2 phi(-(s(x),s(y)) -> -(x,y)) = 3 phi(-(d(x),y) -> -(x,s(y))) = 6 psi(-(0(),0()) -> 0()) = 1 psi(-(s(x),0()) -> s(x)) = 1 psi(-(x,s(y)) -> -(d(x),y)) = 4 psi(d(s(x)) -> x) = 5 psi(-(s(x),s(y)) -> -(x,y)) = 5 psi(-(d(x),y) -> -(x,s(y))) = 6 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.