关键词: 不完备信息系统, 特征关系, 粗糙集, 知识约简

Abstract: The incomplete decision table in which lost and “do not care” unknown values are coexisting is thoroughly investigated．Based on a new dual relation，approach to knowledge reduction and extraction rules in the incomplete decision table is studied． From the view point of new dual relation based rough set model，the knowledge reduction is introduced into the incomplete decision system． The judgment theorems and discernibility matrixes associated with these knowledge reductions are also obtained． The research is meaningful both in the theory and in applications for the acquisition of rules in the complex incomplete decision system.

Key words: incomplete information system, characteristic relation, rough set, knowledge reduction