YES Problem: g(c(x,s(y))) -> g(c(s(x),y)) f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x Proof: Matrix Interpretation Processor: dim=1 interpretation: [d](x0) = x0, [f](x0) = x0 + 5, [g](x0) = 4x0 + 4, [c](x0, x1) = x0 + 2x1 + 1, [s](x0) = x0 orientation: g(c(x,s(y))) = 4x + 8y + 8 >= 4x + 8y + 8 = g(c(s(x),y)) f(c(s(x),y)) = x + 2y + 6 >= x + 2y + 6 = f(c(x,s(y))) f(f(x)) = x + 10 >= x + 10 = f(d(f(x))) f(x) = x + 5 >= x = x problem: g(c(x,s(y))) -> g(c(s(x),y)) f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [d](x0) = [0 0 0]x0 [0 0 0] , [1 0 0] [0] [f](x0) = [0 0 0]x0 + [0] [0 0 0] [1], [1 0 1] [g](x0) = [0 1 0]x0 [0 0 0] , [1 0 0] [1 0 0] [0] [c](x0, x1) = [0 0 0]x0 + [0 0 0]x1 + [1] [0 0 0] [0 0 1] [0], [1 0 0] [0] [s](x0) = [0 0 0]x0 + [0] [0 0 1] [1] orientation: [1 0 0] [1 0 1] [1] [1 0 0] [1 0 1] [0] g(c(x,s(y))) = [0 0 0]x + [0 0 0]y + [1] >= [0 0 0]x + [0 0 0]y + [1] = g(c(s(x),y)) [0 0 0] [0 0 0] [0] [0 0 0] [0 0 0] [0] [1 0 0] [1 0 0] [0] [1 0 0] [1 0 0] [0] f(c(s(x),y)) = [0 0 0]x + [0 0 0]y + [0] >= [0 0 0]x + [0 0 0]y + [0] = f(c(x,s(y))) [0 0 0] [0 0 0] [1] [0 0 0] [0 0 0] [1] [1 0 0] [0] [1 0 0] [0] f(f(x)) = [0 0 0]x + [0] >= [0 0 0]x + [0] = f(d(f(x))) [0 0 0] [1] [0 0 0] [1] problem: f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) Matrix Interpretation Processor: dim=1 interpretation: [d](x0) = x0, [f](x0) = 4x0 + 3, [c](x0, x1) = 2x0 + x1 + 2, [s](x0) = x0 + 2 orientation: f(c(s(x),y)) = 8x + 4y + 27 >= 8x + 4y + 19 = f(c(x,s(y))) f(f(x)) = 16x + 15 >= 16x + 15 = f(d(f(x))) problem: f(f(x)) -> f(d(f(x))) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [d](x0) = [0 0 0]x0 [0 0 0] , [1 1 0] [0] [f](x0) = [0 0 0]x0 + [1] [0 0 0] [0] orientation: [1 1 0] [1] [1 1 0] [0] f(f(x)) = [0 0 0]x + [1] >= [0 0 0]x + [1] = f(d(f(x))) [0 0 0] [0] [0 0 0] [0] problem: Qed