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Proceedings of 2009 International Symposium on Computer Science and Computational Technology (ISCSCT 2009)

Huangshan, China, December 26-28, 2009

Editors: Fei Yu, Guangxue Yue, Jian Shu, Yun Liu

AP Catalog Number: AP-PROC-CS-09CN005

ISBN: 978-952-5726-07-7 (Print), 978-952-5726-08-4 (CD-ROM)

Page(s): 45-48

Aggregated Binary Relations and Rough Approximations

Liping An and Lingyun Tong

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The core concepts of classical rough sets are lower and upper approximations based on indiscernibility relations. In some cases, it is necessary to generalize indiscernibility relation by using some other binary relations. We first consider the indiscernibility relations defined from nominal attributes, similarity relations defined from quantitative attributes, and outranking relations defined from ordinal attributes. These relations defined by single attributes are aggregated into the global relations at the level of the set of attributes. The lower approximation and the upper approximation of the upward and downward unions of decision classes are defined using the global relations. Then, we investigate some of common properties of the relation based lower and upper approximation operations.

Index Terms

binary relations, rough sets, lower and upper approximations, similarity, outranking

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