YES Problem: +(0(),y) -> y +(s(x),y) -> s(+(x,y)) -(0(),y) -> 0() -(x,0()) -> x -(s(x),s(y)) -> -(x,y) Proof: Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = x0 + x1, [-](x0, x1) = 2x0 + 4x1 + 4, [0] = 6, [s](x0) = x0 + 3 orientation: +(0(),y) = y + 6 >= y = y +(s(x),y) = x + y + 3 >= x + y + 3 = s(+(x,y)) -(0(),y) = 4y + 16 >= 6 = 0() -(x,0()) = 2x + 28 >= x = x -(s(x),s(y)) = 2x + 4y + 22 >= 2x + 4y + 4 = -(x,y) problem: +(s(x),y) -> s(+(x,y)) Matrix Interpretation Processor: dim=3 interpretation: [1 1 0] [1 0 0] [+](x0, x1) = [1 0 1]x0 + [0 0 0]x1 [0 0 1] [0 0 0] , [0] [s](x0) = x0 + [1] [1] orientation: [1 1 0] [1 0 0] [1] [1 1 0] [1 0 0] [0] +(s(x),y) = [1 0 1]x + [0 0 0]y + [1] >= [1 0 1]x + [0 0 0]y + [1] = s(+(x,y)) [0 0 1] [0 0 0] [1] [0 0 1] [0 0 0] [1] problem: Qed