{{1, 0, 0, 0, 0, 0, 0, -1/2, -1/2}, {0, 1, 0, 0, 1, 0, -1, 1/2, -1/2}, 
 {0, 0, 1, 0, 1, 1, 0, 1/2, -1/2}, {0, 0, 0, 1, 0, 0, 0, -1/2, -1/2}}
