YES Problem: +(-(x,y),z) -> -(+(x,z),y) -(+(x,y),y) -> x Proof: Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = x0 + x1 + 2, [-](x0, x1) = x0 + x1 + 1 orientation: +(-(x,y),z) = x + y + z + 3 >= x + y + z + 3 = -(+(x,z),y) -(+(x,y),y) = x + 2y + 3 >= x = x problem: +(-(x,y),z) -> -(+(x,z),y) Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = 3x0 + 2x1, [-](x0, x1) = x0 + x1 + 6 orientation: +(-(x,y),z) = 3x + 3y + 2z + 18 >= 3x + y + 2z + 6 = -(+(x,z),y) problem: Qed