YES

---- CR(R)
---- Rule Labeling [van Oostrom, RTA 2008].
R:
+(+(x,y),z) -> +(x,+(y,z))
+(x,+(y,z)) -> +(+(x,y),z)

Label:
[+(+(x,y),z) -> +(x,+(y,z))] = 0
[+(x,+(y,z)) -> +(+(x,y),z)] = 0