NO Problem: a(b(b(x1))) -> b(b(a(a(x1)))) a(a(x1)) -> b(x1) Proof: Unfolding Processor: loop length: 6 terms: a(b(b(b(b(b(b(x887))))))) b(b(a(a(b(b(b(b(x887)))))))) b(b(a(b(b(a(a(b(b(x887))))))))) b(b(a(b(b(a(b(b(a(a(x887)))))))))) b(b(a(b(b(b(b(a(a(a(a(x887))))))))))) b(b(a(b(b(b(b(b(a(a(x887)))))))))) context: b(b([])) substitution: x887 -> x887 Qed