NO Problem: a(a(b(x1))) -> c(c(a(a(a(x1))))) a(c(x1)) -> b(a(x1)) Proof: String Reversal Processor: b(a(a(x1))) -> a(a(a(c(c(x1))))) c(a(x1)) -> a(b(x1)) Unfolding Processor: loop length: 10 terms: b(a(a(a(a(a(a(a(a(x5444))))))))) a(a(a(c(c(a(a(a(a(a(a(x5444))))))))))) a(a(a(c(a(b(a(a(a(a(a(x5444))))))))))) a(a(a(a(b(b(a(a(a(a(a(x5444))))))))))) a(a(a(a(b(a(a(a(c(c(a(a(a(x5444))))))))))))) a(a(a(a(b(a(a(a(c(a(b(a(a(x5444))))))))))))) a(a(a(a(b(a(a(a(a(b(b(a(a(x5444))))))))))))) a(a(a(a(b(a(a(a(a(b(a(a(a(c(c(x5444))))))))))))))) a(a(a(a(b(a(a(a(a(a(a(a(c(c(a(c(c(x5444))))))))))))))))) a(a(a(a(b(a(a(a(a(a(a(a(c(a(b(c(c(x5444))))))))))))))))) context: a(a(a(a([])))) substitution: x5444 -> b(b(c(c(x5444)))) Qed