关键词: 粗糙集，不完备信息系统，特性关系，增量更新

Abstract: The information system based on characteristic relation is an extension of the general model of the information system. It only satisfies the reflexive and can deal with "lost" and "do not care" data in incomplete information systans simultaneously. In real-life applications, the information system may change dynamically according to the variation of objects. This paper discussed properties of approximations in rough sets based on the characteristic relation when one object is added to or deleted from the information system. An incremental algorithm for updating approximations was proposed and experimental evaluation was employed to validate the proposed method.

Key words: Rough sets, Incomplete information systems, Characteristic relation, Incremental updating