YES Problem: .(1(),x) -> x .(x,1()) -> x .(i(x),x) -> 1() .(x,i(x)) -> 1() i(1()) -> 1() i(i(x)) -> x .(i(y),.(y,z)) -> z .(y,.(i(y),z)) -> z .(.(x,y),z) -> .(x,.(y,z)) i(.(x,y)) -> .(i(y),i(x)) Proof: Matrix Interpretation Processor: dim=1 interpretation: [.](x0, x1) = x0 + x1 + 2, [1] = 1, [i](x0) = x0 orientation: .(1(),x) = x + 3 >= x = x .(x,1()) = x + 3 >= x = x .(i(x),x) = 2x + 2 >= 1 = 1() .(x,i(x)) = 2x + 2 >= 1 = 1() i(1()) = 1 >= 1 = 1() i(i(x)) = x >= x = x .(i(y),.(y,z)) = 2y + z + 4 >= z = z .(y,.(i(y),z)) = 2y + z + 4 >= z = z .(.(x,y),z) = x + y + z + 4 >= x + y + z + 4 = .(x,.(y,z)) i(.(x,y)) = x + y + 2 >= x + y + 2 = .(i(y),i(x)) problem: i(1()) -> 1() i(i(x)) -> x .(.(x,y),z) -> .(x,.(y,z)) i(.(x,y)) -> .(i(y),i(x)) Matrix Interpretation Processor: dim=1 interpretation: [.](x0, x1) = x0 + x1 + 2, [1] = 0, [i](x0) = 4x0 orientation: i(1()) = 0 >= 0 = 1() i(i(x)) = 16x >= x = x .(.(x,y),z) = x + y + z + 4 >= x + y + z + 4 = .(x,.(y,z)) i(.(x,y)) = 4x + 4y + 8 >= 4x + 4y + 2 = .(i(y),i(x)) problem: i(1()) -> 1() i(i(x)) -> x .(.(x,y),z) -> .(x,.(y,z)) Matrix Interpretation Processor: dim=1 interpretation: [.](x0, x1) = 4x0 + x1 + 4, [1] = 0, [i](x0) = 3x0 + 6 orientation: i(1()) = 6 >= 0 = 1() i(i(x)) = 9x + 24 >= x = x .(.(x,y),z) = 16x + 4y + z + 20 >= 4x + 4y + z + 8 = .(x,.(y,z)) problem: Qed