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