Firstly , we constructed a relative difference comparison table based on the rough set theory to effectively and efficiently achieve the better attribute reduction . then the relative difference comparison table is combined with the heuristic knowledge to design three algorithms respectively : the improved algorithm for attribute reduction , the judge algorithm of attribute reduction , and some improvements for a widely used value reduction method are also achieved in this paper 首先在粗糙集理论的基础上构造出了相对差异比较表，然后把它与启发性知识相结合分别设计了基于相对差异比较表的改进的属性约简算法、属性约简的判定算法，和提取规则的值约简算法。
