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