NO Problem: a(x1) -> x1 a(b(x1)) -> b(a(c(b(a(a(x1)))))) b(x1) -> x1 c(c(x1)) -> x1 Proof: String Reversal Processor: a(x1) -> x1 b(a(x1)) -> a(a(b(c(a(b(x1)))))) b(x1) -> x1 c(c(x1)) -> x1 Unfolding Processor: loop length: 8 terms: b(a(a(a(x46599)))) a(a(b(c(a(b(a(a(x46599)))))))) a(a(b(c(b(a(a(x46599))))))) a(a(b(c(a(a(b(c(a(b(a(x46599))))))))))) a(a(b(c(a(b(c(a(b(a(x46599)))))))))) a(a(b(c(b(c(a(b(a(x46599))))))))) a(a(b(c(c(a(b(a(x46599)))))))) a(a(b(a(b(a(x46599)))))) context: a(a([])) substitution: x46599 -> b(c(a(b(x46599)))) Qed