NO Problem: +(0(),y) -> y +(s(0()),y) -> s(y) +(s(s(x)),y) -> s(s(+(y,x))) +(x,+(y,z)) -> +(+(z,y),x) Proof: Nonconfluence Processor: terms: +(y,z) *<- +(0(),+(y,z)) ->* +(+(z,y),0()) Qed