Converse approximation and rule extraction from decision tables in rough set theory
- 作者：Yuhua Qian ; Jiye Liang ; Chuangyin Dang
- 关键词：Rough set theory ; Converse approximation ; Decision table ; Decision rules ; Rule extracting
- 刊名：Computers and Mathematics with Applications
- 出版年：2008
- 期刊代码：37_08981221
- 类别：cp
- 出版时间：April 2008
- 卷：55
- 期：8
- 页码：1754-1765
- 文件大小：278 K
摘要
In this paper, the concept of a granulation order is proposed in an information system. The converse approximation of a target concept under a granulation order is defined and some of its important properties are obtained, which can be used to characterize the structure of a set approximation. For a subset of the universe in an information system, its converge degree is monotonously increasing under a granulation order. This means that a proper family of granulations can be chosen for a target concept approximation according to user requirements. As an application of the converse approximation, an algorithm based on the converse approximation called REBCA is designed for decision-rule extraction from a decision table, which has a time complexity of 
, and its practical applications are illustrated by two examples.