rough computational approach to uar based on dominance matrix in iois粗略的计算方法基于优势矩阵uar信息系统.pdf

Intelligent Information Management, 2011, 3, 131-136 doi:10.4236/iim.2011.34016 Published Online July 2011 (http://www.SciRP.org/journal/iim) Rough Computational Approach to UAR based on Dominance Matrix in IOIS Xiaoyan Zhang, Weihua Xu 1 Chongqing University of Technology, Chongqing, China E-mail: zhangxyms@, chxuwh@ Received March 28, 2011; revised June 30, 2011; accepted July 7, 2011 Abstract Rough set theory is a new mathematical tool to deal with vagueness and uncertainty. The classical rough set theory based on equivalence relation has made a great progress, while the equivalence relation is too harsh to meet and is extended to dominance relation in real world. It is important to investigate rough computational methods for rough set theory, which is one of the bottleneck problems in the development of rough set theory. In this article, rough computational approach to upper approximation reduction (UAR) is discussed based on dominance matrix in inconsistent ordered information systems (IOIS). The algorithm of upper approximation reduction is obtained, from which we can provide approach to upper approximation reduction operated sim- ply in inconsistent systems based on dominance relations. Finally, an example illustrates the validity of this method, and shows the method is excellent to a complicated information system. Keywords: Dominance Relation, Information System, Rough Set, Upper Approximation Reduction 1. Introduction edge reductions are very poor in inconsistent ordered in- formation systems until now. The rough set theory, proposed by Pawlak in the early