YES ---- CR(R) ---- [Knuth and Bendix, 1970] R: +(x,0()) -> x +(x,s(y)) -> s(+(x,y)) d(0()) -> 0() d(s(x)) -> s(s(d(x))) f(0()) -> 0() f(s(x)) -> +(+(s(x),s(x)),s(x)) f(g(0())) -> +(+(g(0()),g(0())),g(0())) g(x) -> s(d(x)) CP(R): f(s(d(0()))) -> +(+(g(0()),g(0())),g(0()))