YES ---- CR(R) ---- R : left-linear, C : CR and CP-closing, and Cdup/R : SN R: -(+(x(),-(x()))) -> 0() +(x(),-(x())) -> 0() 0() -> -(0()) CP(R): -(0()) -> 0() critical-pair-closing system C: -(+(x(),-(x()))) -> 0() 0() -> -(0()) CR(C): see below. ---- CR(R) ---- R : linear and strongly closed [Huet, 1980] R: -(+(x(),-(x()))) -> 0() 0() -> -(0()) CP(R):