Abstract: Classic rough sets theory is based on complete information，but for some real reasons，there are many information systems which are incomplete.Tolerant relation is an important concept in incomplete information systems，how to compute tolerant classes efficiently play a significant role in improving performance of correlative algorithms.To overcome the limitation of time-consuming of computing tolerant classes，a quick method for computing tolerant classes is provided.Experimental results verify the validity and efficiency of the quick algorithm，and the quick method is more efficient than those existing methods.

Key words: incomplete information systems, tolerant classes, radix sort, quick method

摘要： 经典粗糙集理论是建立在完备信息基础上的，然而现实中，由于各种原因，很多信息系统是非完备的。相容关系是非完备信息系统的核心概念之一，如何高效地计算相容类对提高各相关算法的性能至关重要。针对非完备信息系统中求解相容类计算耗时过大的缺陷，提出了一种求解相容类的快速计算方法。实验结果也进一步表明，该方法能够有效地降低计算耗时，在效率上较现有方法有显著提高。

关键词: 非完备信息系统, 相容类, 基数排序, 快速方法