Improved Recalculation of Relative Reducts Based on Update of Objects in Decision Table

Abstract

In this paper, we improve a method proposed by Hashimoto et al. to quickly calculate relative reducts after the decision table is updated. In general, when a decision table that has already created relative reducts is updated, it is necessary to calculate all relative reducts again. However, recalculation is very computationally intensive and takes a lot of processing time. Hashimoto et al. proposed a method to quickly calculate relative reducts after the decision table is updated. However, the problem of this method is that it cannot be used for decision table with inconsistent data. Therefore, we revise Hashimoto et al.’s method that can be used even with inconsistent data by supporting the cases (1) some data becomes inconsistent dada by adding some objects to decision table, and (2) some inconsistent data becomes consistent data by deleting some objects from decision table.