Converse approximation and rule extraction from decision tables in rough set theory

  • Authors:

  • Yuhua Qian;Jiye Liang;Chuangyin Dang

  • Affiliations:

  • Key Laboratory of Computational Intelligence and Chinese Information Processing of Ministry of Education, Taiyuan, 030006, China and School of Computer and Information Technology, Shanxi Universit ...;Key Laboratory of Computational Intelligence and Chinese Information Processing of Ministry of Education, Taiyuan, 030006, China and School of Computer and Information Technology, Shanxi Universit ...;Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Hong Kong

  • Venue:
  • Computers & Mathematics with Applications
  • Year:
  • 2008

Quantified Score

Hi-index 0.09

Visualization

Abstract

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 O(m2|C|^2|U|log"2|U|), and its practical applications are illustrated by two examples.