YES ---- CR(R) ---- R : left-linear, C : CR and CP-closing, and Cdup/R : SN R: -(+(x,y)) -> +(-(x),-(y)) +(x,y) -> +(y,x) CP(R): -(+(___y10,___y9)) -> +(-(___y9),-(___y10)) critical-pair-closing system C: -(+(x,y)) -> +(-(x),-(y)) +(x,y) -> +(y,x) CR(C): see below. ---- CR(R) ---- R : linear and strongly closed [Huet, 1980] R: -(+(x,y)) -> +(-(x),-(y)) +(x,y) -> +(y,x) CP(R): -(+(___y26,___y25)) -> +(-(___y25),-(___y26))