离散型随机变量独立性的判定

Judgement of independence of discrete random variables

借助于条件数学期望给出了离散型随机变量相互独立的一个充分必要条件和一个充分条件，其中的充分必要条件推广了已有的结论。

With conditional expectation, a mutually independent necessary and sufficient condition of two discrete random variables is presented in this paper, which extends the relative conclusion of previous theory.In addition, a mutually independent sufficient condition of two discrete random variables is presented.