NO Problem: a(x1) -> x1 a(b(x1)) -> b(a(c(b(a(x1))))) b(x1) -> a(x1) c(c(x1)) -> x1 Proof: String Reversal Processor: a(x1) -> x1 b(a(x1)) -> a(b(c(a(b(x1))))) b(x1) -> a(x1) c(c(x1)) -> x1 Unfolding Processor: loop length: 8 terms: b(a(a(x36400))) a(b(c(a(b(a(x36400)))))) a(b(c(b(a(x36400))))) a(b(c(a(b(c(a(b(x36400)))))))) a(b(c(b(c(a(b(x36400))))))) a(b(c(a(c(a(b(x36400))))))) a(b(c(c(a(b(x36400)))))) a(b(a(b(x36400)))) context: a([]) substitution: x36400 -> x36400 Qed