YES Problem: w(r(x)) -> r(w(x)) b(r(x)) -> r(b(x)) b(w(x)) -> w(b(x)) Proof: String Reversal Processor: r(w(x)) -> w(r(x)) r(b(x)) -> b(r(x)) w(b(x)) -> b(w(x)) KBO Processor: weight function: w0 = 1 w(b) = w(w) = 1 w(r) = 0 precedence: r > w > b problem: Qed