You may wonder whether in (16) the last relation follows from the others, but the answer is no. To see this, imagine that a chip is drawn from a box containing 4 chips numbered 000, 011, 101, 110, and let A, B, C be the events that the first, scond, and thir digit, respectively, on the drawn chip is 1, shp that then the first three formulas in (16) hold but the last one does not hold.