YES Problem: f(s(x),y) -> f(x,s(s(x))) f(x,s(s(y))) -> f(y,x) Proof: Matrix Interpretation Processor: dim=1 interpretation: [f](x0, x1) = 6x0 + x1 + 4, [s](x0) = 4x0 + 4 orientation: f(s(x),y) = 24x + y + 28 >= 22x + 24 = f(x,s(s(x))) f(x,s(s(y))) = 6x + 16y + 24 >= x + 6y + 4 = f(y,x) problem: Qed