Reseach Of The Rough Set Model Based On Dominance Relation And Its Konwledge Reduction

Rough set theory is a new mathematic tool developed by Professor Pawlak early in the 1980 s for dealing with uncertain and incomplete knowledge. In addition to the data set, it does not require any prior information. Therefore, it is suitable to discover potentially useful rules hidden in data.Firstly, the complete decision system based on dominance relation rough set model is introduced. However, due to effect of decision-makers' subjective preference and insufficient data, the actual system frequently involves preference and incomplete information decision system rough set model. Therefore, it is practical significance to research incomplete decision system. To deal with incomplete decision information system with preference information, a rough set model in set valued information system based on dominance value relation is presented, and the relevant theorem and axiom are also discussed. Simultaneously, to improve robust of data processing, the new model is expended to variable precious set-valued system. Secondly, the uncertainty measurement problem information system based on dominance relation is discussed, and a new modified rough entropy is proposed in set-valued system based on dominance relation. At the same time the modified rough entropy is introduced to variable precision rough set model based on dominance relation. At last from further studying the attribute reduction method of decision system, a algorithm of attribute reduction of set-valued decision system based on identification matrix, an attribute reduction algorithm of value decision system based on importance of attribute are presented, and an attribute reduction algorithm based on attribute importance in the dominance value relation variable precision decision system is also given.