NO Problem: b(a(a(x1))) -> a(x1) a(a(a(x1))) -> b(b(b(x1))) b(b(x1)) -> a(b(a(x1))) Proof: Unfolding Processor: loop length: 6 terms: a(a(a(b(a(a(x2917)))))) b(b(b(b(a(a(x2917)))))) a(b(a(b(b(a(a(x2917))))))) a(b(a(a(b(a(a(a(x2917)))))))) a(b(a(a(b(b(b(b(x2917)))))))) a(b(a(a(a(b(a(b(b(x2917))))))))) context: a(b([])) substitution: x2917 -> b(a(x2917)) Qed