YES ---- CR(R) ---- R : left-linear, C : CR and CP-closing, and Cdup/R : SN R: a() -> b() a() -> c() a() -> e() b() -> d() c() -> a() d() -> a() d() -> e() g(x) -> h(a()) h(x) -> e() CP(R): b() -> c() b() -> e() c() -> b() c() -> e() e() -> b() e() -> c() a() -> e() e() -> a() critical-pair-closing system C: a() -> e() b() -> d() c() -> a() d() -> e() h(x) -> e() CR(C): see below. ---- CR(R) ---- R : linear and strongly closed [Huet, 1980] R: a() -> e() b() -> d() c() -> a() d() -> e() h(x) -> e() CP(R):