ID3算法是一种贪心算法，用来构造决策树。ID3算法起源于概念学习系统（CLS），以信息熵的下降速度为选取测试属性的标准，即在每个节点选取还尚未被用来划分的具有最高信息增益的属性作为划分标准，然后继续这个过程，直到生成的决策树能完美分类训练样例。(The ID3 algorithm is a greedy algorithm, which is used to construct a decision tree. ID3 algorithm originated from the concept of learning system (CLS), with the descending velocity of the information entropy for choosing the test attribute selection criteria, namely in each node has not yet been used to attribute with the highest information gain division as the division standard, then continues the process until the decision tree generated perfect classification of training examples.)