Stated in bits, the law is formula_41. In Shannon's information theory, formula_12, formula_13, and formula_44 are information sources. The condition that if formula_13 never changes moves, the uncertainty in outcomes is no less than the uncertainty in formula_12's move is expressed as formula_47, and since formula_13's strategy is a deterministic function of formula_12 set formula_50. With the rules of the game expressed this way, it can be shown that formula_51. Ashby described the law of requisite variety as related to the tenth theorem in Shannon's Mathematical Theory of Communication (1948):