Improvement of Discernibility Matrix and the Computation of a Core

Rough set theory is a new mathematical tool to deal with imprecise, incomplete and inconsistent data. Attributes reduction is one of important parts researched in rough set theory. The attributes core of a decision table is the start point to many existing algorithms of attributes reduction. In order to correct the error of HU'method based on discernibility matrix for computing the core of a decision table, Ye Dong-yi proposes new discernibility matrix and the computation of a core, but the complexity is too high. Therefore a improved discernibility matrix definition together with a method for computing the core is introduced, which corrects the error of HU'method and is with low complexity.