YES Problem: strict: b(c(a(x1))) -> d(d(x1)) b(x1) -> c(c(x1)) a(a(x1)) -> a(x1) weak: a(b(x1)) -> d(x1) d(x1) -> a(b(x1)) Proof: String Reversal Processor: strict: a(c(b(x1))) -> d(d(x1)) b(x1) -> c(c(x1)) a(a(x1)) -> a(x1) weak: b(a(x1)) -> d(x1) d(x1) -> b(a(x1)) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [c](x0) = [0 0 1]x0 [0 0 0] , [1 2 0] [1] [d](x0) = [0 0 0]x0 + [0] [0 0 0] [2], [1 2 0] [1] [a](x0) = [0 0 0]x0 + [0] [0 0 0] [3], [1 2 0] [0] [b](x0) = [0 2 0]x0 + [0] [0 0 0] [2] orientation: [1 2 0] [5] [1 2 0] [2] a(c(b(x1))) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = d(d(x1)) [0 0 0] [3] [0 0 0] [2] [1 2 0] [0] [1 0 0] b(x1) = [0 2 0]x1 + [0] >= [0 0 0]x1 = c(c(x1)) [0 0 0] [2] [0 0 0] [1 2 0] [2] [1 2 0] [1] a(a(x1)) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = a(x1) [0 0 0] [3] [0 0 0] [3] [1 2 0] [1] [1 2 0] [1] b(a(x1)) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = d(x1) [0 0 0] [2] [0 0 0] [2] [1 2 0] [1] [1 2 0] [1] d(x1) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = b(a(x1)) [0 0 0] [2] [0 0 0] [2] problem: strict: b(x1) -> c(c(x1)) weak: b(a(x1)) -> d(x1) d(x1) -> b(a(x1)) String Reversal Processor: strict: b(x1) -> c(c(x1)) weak: a(b(x1)) -> d(x1) d(x1) -> a(b(x1)) Arctic Interpretation Processor: dimension: 1 interpretation: [c](x0) = x0, [d](x0) = 8x0, [a](x0) = x0, [b](x0) = 8x0 orientation: b(x1) = 8x1 >= x1 = c(c(x1)) a(b(x1)) = 8x1 >= 8x1 = d(x1) d(x1) = 8x1 >= 8x1 = a(b(x1)) problem: strict: weak: a(b(x1)) -> d(x1) d(x1) -> a(b(x1)) Qed