YES Problem: a(b(x)) -> b(b(a(x))) Proof: String Reversal Processor: b(a(x)) -> a(b(b(x))) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [0] [a](x0) = [0 1 1]x0 + [1] [0 1 1] [1], [1 1 1] [1] [b](x0) = [0 1 0]x0 + [0] [0 0 1] [0] orientation: [1 2 2] [3] [1 2 2] [2] b(a(x)) = [0 1 1]x + [1] >= [0 1 1]x + [1] = a(b(b(x))) [0 1 1] [1] [0 1 1] [1] problem: Qed