YES # parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023) Consider the left-linear TRS R: +(x,0()) -> x +(x,s(y)) -> s(+(x,y)) d(0()) -> 0() d(s(x)) -> s(s(d(x))) f(0()) -> 0() f(s(x)) -> +(+(s(x),s(x)),s(x)) f(g(0())) -> +(+(g(0()),g(0())),g(0())) g(x) -> s(d(x)) Let C be the following subset of R: +(x,s(y)) -> s(+(x,y)) d(s(x)) -> s(s(d(x))) f(s(x)) -> +(+(s(x),s(x)),s(x)) g(x) -> s(d(x)) The TRS R is left-linear and all parallel critical pairs are joinable by C. Therefore, the confluence of R is equivalent to that of C. # parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023) Consider the left-linear TRS R: +(x,s(y)) -> s(+(x,y)) d(s(x)) -> s(s(d(x))) f(s(x)) -> +(+(s(x),s(x)),s(x)) g(x) -> s(d(x)) Let C be the following subset of R: +(x,s(y)) -> s(+(x,y)) f(s(x)) -> +(+(s(x),s(x)),s(x)) The TRS R is left-linear and all parallel critical pairs are joinable by C. Therefore, the confluence of R is equivalent to that of C. # parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023) Consider the left-linear TRS R: +(x,s(y)) -> s(+(x,y)) f(s(x)) -> +(+(s(x),s(x)),s(x)) Let C be the following subset of R: +(x,s(y)) -> s(+(x,y)) The TRS R is left-linear and all parallel critical pairs are joinable by C. Therefore, the confluence of R is equivalent to that of C. # parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023) Consider the left-linear TRS R: +(x,s(y)) -> s(+(x,y)) Let C be the following subset of R: (empty) The TRS R is left-linear and all parallel critical pairs are joinable by C. Therefore, the confluence of R is equivalent to that of C. # Compositional parallel rule labeling (Shintani and Hirokawa 2022). Consider the left-linear TRS R: (empty) Let C be the following subset of R: (empty) All parallel critical peaks (except C's) are decreasing wrt rule labeling: 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.