YES ---- CR(R) ---- R : left-linear, C : CR and CP-closing, and Cdup/R : SN R: -(+(x,y)) -> +(-(x),-(y)) +(-(x),-(y)) -> -(+(x,y)) CP(R): +(+(-(___y21),-(___y22)),-(___y24)) -> -(+(+(___y21,___y22),___y24)) +(-(___y23),+(-(___y21),-(___y22))) -> -(+(___y23,+(___y21,___y22))) -(-(+(___y25,___y26))) -> +(-(-(___y25)),-(-(___y26))) critical-pair-closing system C: -(+(x,y)) -> +(-(x),-(y)) CR(C): see below. ---- CR(R) ---- R : left-linear, C : CR and CP-closing, and Cdup/R : SN R: -(+(x,y)) -> +(-(x),-(y)) CP(R): critical-pair-closing system C: CR(C): see below. ---- CR(R) ---- R is empty.