Objects' combination based simple computation of attribute core

Rough set theory is emerging as a new tool for dealing with fuzzy and uncertain data. Attribute reduction is one of the most important parts in rough set theory. The attribute core of a decision table is often the start point and key of many information reduction procedures. Hu's method (1995) for computing the attribute core based on the discernibility matrix was wrong because of the neglect of some factors. The error was corrected by Dongyi Ye, but the complexity of his algorithm was too high. In this paper, we present a new algorithm based on object combination. The algorithm corrects Hu's error and has less complexity than Ye's and Hu's methods.