YES Problem: a(a(x1)) -> b(c(x1)) b(b(x1)) -> c(d(x1)) b(x1) -> a(x1) c(c(x1)) -> d(f(x1)) d(d(x1)) -> f(f(f(x1))) d(x1) -> b(x1) f(f(x1)) -> g(a(x1)) g(g(x1)) -> a(x1) Proof: String Reversal Processor: a(a(x1)) -> c(b(x1)) b(b(x1)) -> d(c(x1)) b(x1) -> a(x1) c(c(x1)) -> f(d(x1)) d(d(x1)) -> f(f(f(x1))) d(x1) -> b(x1) f(f(x1)) -> a(g(x1)) g(g(x1)) -> a(x1) Matrix Interpretation Processor: dim=3 interpretation: [1 1 0] [0] [g](x0) = [0 1 1]x0 + [1] [0 0 0] [0], [1 1 0] [f](x0) = [0 0 0]x0 [0 0 0] , [1 0 1] [d](x0) = [0 0 0]x0 [0 1 0] , [1 0 1] [b](x0) = [0 0 0]x0 [0 0 0] , [1 0 1] [c](x0) = [0 0 0]x0 [0 0 0] , [1 0 1] [a](x0) = [0 0 0]x0 [0 0 0] orientation: [1 0 1] [1 0 1] a(a(x1)) = [0 0 0]x1 >= [0 0 0]x1 = c(b(x1)) [0 0 0] [0 0 0] [1 0 1] [1 0 1] b(b(x1)) = [0 0 0]x1 >= [0 0 0]x1 = d(c(x1)) [0 0 0] [0 0 0] [1 0 1] [1 0 1] b(x1) = [0 0 0]x1 >= [0 0 0]x1 = a(x1) [0 0 0] [0 0 0] [1 0 1] [1 0 1] c(c(x1)) = [0 0 0]x1 >= [0 0 0]x1 = f(d(x1)) [0 0 0] [0 0 0] [1 1 1] [1 1 0] d(d(x1)) = [0 0 0]x1 >= [0 0 0]x1 = f(f(f(x1))) [0 0 0] [0 0 0] [1 0 1] [1 0 1] d(x1) = [0 0 0]x1 >= [0 0 0]x1 = b(x1) [0 1 0] [0 0 0] [1 1 0] [1 1 0] f(f(x1)) = [0 0 0]x1 >= [0 0 0]x1 = a(g(x1)) [0 0 0] [0 0 0] [1 2 1] [1] [1 0 1] g(g(x1)) = [0 1 1]x1 + [2] >= [0 0 0]x1 = a(x1) [0 0 0] [0] [0 0 0] problem: a(a(x1)) -> c(b(x1)) b(b(x1)) -> d(c(x1)) b(x1) -> a(x1) c(c(x1)) -> f(d(x1)) d(d(x1)) -> f(f(f(x1))) d(x1) -> b(x1) f(f(x1)) -> a(g(x1)) Arctic Interpretation Processor: dimension: 1 interpretation: [g](x0) = 5x0, [f](x0) = 8x0, [d](x0) = 12x0, [b](x0) = 12x0, [c](x0) = 10x0, [a](x0) = 11x0 orientation: a(a(x1)) = 22x1 >= 22x1 = c(b(x1)) b(b(x1)) = 24x1 >= 22x1 = d(c(x1)) b(x1) = 12x1 >= 11x1 = a(x1) c(c(x1)) = 20x1 >= 20x1 = f(d(x1)) d(d(x1)) = 24x1 >= 24x1 = f(f(f(x1))) d(x1) = 12x1 >= 12x1 = b(x1) f(f(x1)) = 16x1 >= 16x1 = a(g(x1)) problem: a(a(x1)) -> c(b(x1)) c(c(x1)) -> f(d(x1)) d(d(x1)) -> f(f(f(x1))) d(x1) -> b(x1) f(f(x1)) -> a(g(x1)) Arctic Interpretation Processor: dimension: 1 interpretation: [g](x0) = 4x0, [f](x0) = 4x0, [d](x0) = 12x0, [b](x0) = x0, [c](x0) = 8x0, [a](x0) = 4x0 orientation: a(a(x1)) = 8x1 >= 8x1 = c(b(x1)) c(c(x1)) = 16x1 >= 16x1 = f(d(x1)) d(d(x1)) = 24x1 >= 12x1 = f(f(f(x1))) d(x1) = 12x1 >= x1 = b(x1) f(f(x1)) = 8x1 >= 8x1 = a(g(x1)) problem: a(a(x1)) -> c(b(x1)) c(c(x1)) -> f(d(x1)) f(f(x1)) -> a(g(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [g](x0) = [0 2 ]x0, [1 2] [f](x0) = [0 0]x0, [0 1] [d](x0) = [3 1]x0, [0 -&] [b](x0) = [1 0 ]x0, [3 1 ] [c](x0) = [3 -&]x0, [2 1] [a](x0) = [1 0]x0 orientation: [4 3] [3 1 ] a(a(x1)) = [3 2]x1 >= [3 -&]x1 = c(b(x1)) [6 4] [5 3] c(c(x1)) = [6 4]x1 >= [3 1]x1 = f(d(x1)) [2 3] [2 3] f(f(x1)) = [1 2]x1 >= [1 2]x1 = a(g(x1)) problem: a(a(x1)) -> c(b(x1)) f(f(x1)) -> a(g(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 1] [g](x0) = [2 1]x0, [2 1] [f](x0) = [0 2]x0, [0 0] [b](x0) = [0 0]x0, [1 0] [c](x0) = [0 0]x0, [2 2] [a](x0) = [2 0]x0 orientation: [4 4] [1 1] a(a(x1)) = [4 4]x1 >= [0 0]x1 = c(b(x1)) [4 3] [4 3] f(f(x1)) = [2 4]x1 >= [2 3]x1 = a(g(x1)) problem: f(f(x1)) -> a(g(x1)) Arctic Interpretation Processor: dimension: 3 interpretation: [0 -& 0 ] [g](x0) = [0 -& 2 ]x0 [0 -& 2 ] , [0 0 2 ] [f](x0) = [-& 0 2 ]x0 [1 -& 1 ] , [0 0 0 ] [a](x0) = [-& 0 0 ]x0 [0 0 0 ] orientation: [3 0 3] [0 -& 2 ] f(f(x1)) = [3 0 3]x1 >= [0 -& 2 ]x1 = a(g(x1)) [2 1 3] [0 -& 2 ] problem: Qed