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