NO Problem: nats() -> :(0(),inc(nats())) inc(:(x,y)) -> :(s(x),inc(y)) hd(:(x,y)) -> x tl(:(x,y)) -> y inc(tl(nats())) -> tl(inc(nats())) Proof: Containment Processor: loop length: 1 terms: nats() context: :(0(),inc([])) substitution: Qed