NO Problem: a(x1) -> x1 a(b(x1)) -> b(b(a(a(c(a(x1)))))) b(x1) -> x1 c(c(x1)) -> x1 Proof: Unfolding Processor: loop length: 8 terms: a(b(c(b(b(x51367))))) b(b(a(a(c(a(c(b(b(x51367))))))))) b(b(a(a(c(c(b(b(x51367)))))))) b(b(a(a(b(b(x51367)))))) b(b(a(b(b(a(a(c(a(b(x51367)))))))))) b(b(b(b(a(a(c(a(b(a(a(c(a(b(x51367)))))))))))))) b(b(b(b(a(a(c(a(b(a(c(a(b(x51367))))))))))))) b(b(b(b(a(a(c(a(b(c(a(b(x51367)))))))))))) context: b(b(b(b(a(a(c([]))))))) substitution: x51367 -> a(a(c(a(x51367)))) Qed