YES Problem: +(-(x,y),z) -> -(+(x,z),y) -(+(x,y),y) -> x Proof: Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = x0 + 2x1 + 2, [-](x0, x1) = x0 + 2x1 + 1 orientation: +(-(x,y),z) = x + 2y + 2z + 3 >= x + 2y + 2z + 3 = -(+(x,z),y) -(+(x,y),y) = x + 4y + 3 >= x = x problem: +(-(x,y),z) -> -(+(x,z),y) Matrix Interpretation Processor: dim=3 interpretation: [1 0 1] [1 0 0] [+](x0, x1) = [0 0 0]x0 + [0 1 0]x1 [0 0 1] [1 0 0] , [1 0 0] [1 0 0] [0] [-](x0, x1) = [0 0 0]x0 + [0 0 0]x1 + [0] [0 0 1] [0 0 0] [1] orientation: [1 0 1] [1 0 0] [1 0 0] [1] [1 0 1] [1 0 0] [1 0 0] [0] +(-(x,y),z) = [0 0 0]x + [0 0 0]y + [0 1 0]z + [0] >= [0 0 0]x + [0 0 0]y + [0 0 0]z + [0] = -(+(x,z),y) [0 0 1] [0 0 0] [1 0 0] [1] [0 0 1] [0 0 0] [1 0 0] [1] problem: Qed