YES Problem: f(s(x),y) -> f(x,s(x)) f(x,s(y)) -> f(y,x) f(c(x),y) -> f(x,s(x)) Proof: Matrix Interpretation Processor: dim=1 interpretation: [f](x0, x1) = 4x0 + 2x1, [s](x0) = 4x0 + 6, [c](x0) = 3x0 + 3 orientation: f(s(x),y) = 16x + 2y + 24 >= 12x + 12 = f(x,s(x)) f(x,s(y)) = 4x + 8y + 12 >= 2x + 4y = f(y,x) f(c(x),y) = 12x + 2y + 12 >= 12x + 12 = f(x,s(x)) problem: f(c(x),y) -> f(x,s(x)) Matrix Interpretation Processor: dim=1 interpretation: [f](x0, x1) = 4x0 + 4x1, [s](x0) = x0, [c](x0) = 4x0 + 4 orientation: f(c(x),y) = 16x + 4y + 16 >= 8x = f(x,s(x)) problem: Qed