YES Problem: R(x1) -> r(x1) r(p(x1)) -> p(p(r(P(x1)))) r(r(x1)) -> x1 r(P(P(x1))) -> P(P(r(x1))) p(P(x1)) -> x1 P(p(x1)) -> x1 r(R(x1)) -> x1 R(r(x1)) -> x1 Proof: Arctic Interpretation Processor: dimension: 1 interpretation: [P](x0) = x0, [p](x0) = x0, [r](x0) = 1x0, [R](x0) = 1x0 orientation: R(x1) = 1x1 >= 1x1 = r(x1) r(p(x1)) = 1x1 >= 1x1 = p(p(r(P(x1)))) r(r(x1)) = 2x1 >= x1 = x1 r(P(P(x1))) = 1x1 >= 1x1 = P(P(r(x1))) p(P(x1)) = x1 >= x1 = x1 P(p(x1)) = x1 >= x1 = x1 r(R(x1)) = 2x1 >= x1 = x1 R(r(x1)) = 2x1 >= x1 = x1 problem: R(x1) -> r(x1) r(p(x1)) -> p(p(r(P(x1)))) r(P(P(x1))) -> P(P(r(x1))) p(P(x1)) -> x1 P(p(x1)) -> x1 Arctic Interpretation Processor: dimension: 2 interpretation: [0 0] [P](x0) = [0 0]x0, [0 0] [p](x0) = [0 0]x0, [0 0] [r](x0) = [0 0]x0, [2 2] [R](x0) = [1 2]x0 orientation: [2 2] [0 0] R(x1) = [1 2]x1 >= [0 0]x1 = r(x1) [0 0] [0 0] r(p(x1)) = [0 0]x1 >= [0 0]x1 = p(p(r(P(x1)))) [0 0] [0 0] r(P(P(x1))) = [0 0]x1 >= [0 0]x1 = P(P(r(x1))) [0 0] p(P(x1)) = [0 0]x1 >= x1 = x1 [0 0] P(p(x1)) = [0 0]x1 >= x1 = x1 problem: r(p(x1)) -> p(p(r(P(x1)))) r(P(P(x1))) -> P(P(r(x1))) p(P(x1)) -> x1 P(p(x1)) -> x1 String Reversal Processor: p(r(x1)) -> P(r(p(p(x1)))) P(P(r(x1))) -> r(P(P(x1))) P(p(x1)) -> x1 p(P(x1)) -> x1 Matrix Interpretation Processor: dim=3 interpretation: [1 1 0] [P](x0) = [0 0 1]x0 [0 1 0] , [1 0 0] [p](x0) = [0 0 1]x0 [0 1 0] , [1 0 0] [0] [r](x0) = [0 0 0]x0 + [0] [0 1 1] [1] orientation: [1 0 0] [0] [1 0 0] [0] p(r(x1)) = [0 1 1]x1 + [1] >= [0 1 1]x1 + [1] = P(r(p(p(x1)))) [0 0 0] [0] [0 0 0] [0] [1 1 1] [1] [1 1 1] [0] P(P(r(x1))) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = r(P(P(x1))) [0 1 1] [1] [0 1 1] [1] [1 0 1] P(p(x1)) = [0 1 0]x1 >= x1 = x1 [0 0 1] [1 1 0] p(P(x1)) = [0 1 0]x1 >= x1 = x1 [0 0 1] problem: p(r(x1)) -> P(r(p(p(x1)))) P(p(x1)) -> x1 p(P(x1)) -> x1 Arctic Interpretation Processor: dimension: 2 interpretation: [1 1] [P](x0) = [0 0]x0, [0 3 ] [p](x0) = [-& 0 ]x0, [0 0] [r](x0) = [0 3]x0 orientation: [3 6] [1 4] p(r(x1)) = [0 3]x1 >= [0 3]x1 = P(r(p(p(x1)))) [1 4] P(p(x1)) = [0 3]x1 >= x1 = x1 [3 3] p(P(x1)) = [0 0]x1 >= x1 = x1 problem: p(r(x1)) -> P(r(p(p(x1)))) p(P(x1)) -> x1 String Reversal Processor: r(p(x1)) -> p(p(r(P(x1)))) P(p(x1)) -> x1 Matrix Interpretation Processor: dim=3 interpretation: [1] [P](x0) = x0 + [0] [0], [0] [p](x0) = x0 + [1] [1], [1 1 0] [r](x0) = [0 1 1]x0 [0 1 1] orientation: [1 1 0] [1] [1 1 0] [1] r(p(x1)) = [0 1 1]x1 + [2] >= [0 1 1]x1 + [2] = p(p(r(P(x1)))) [0 1 1] [2] [0 1 1] [2] [1] P(p(x1)) = x1 + [1] >= x1 = x1 [1] problem: r(p(x1)) -> p(p(r(P(x1)))) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [P](x0) = [-& -&]x0, [1 0] [p](x0) = [3 1]x0, [1 3] [r](x0) = [2 3]x0 orientation: [6 4] [4 -&] r(p(x1)) = [6 4]x1 >= [5 -&]x1 = p(p(r(P(x1)))) problem: Qed