关键词: 构造性覆盖算法（CCA）, 边界域样本处理, 三支决策

Abstract: The three-way decisions model based on constructive covering algorithm (CCA) produces automatically three regions: positive regions (POS), negative regions (NEG) and boundary regions (BND) according to the distribution characteristic of samples. The model provides a new idea to deal with samples in BND for the theory of three-way decisions. This paper proposes two methods to deal with samples in BND: The first method deals with all samples in BND, which gives three principles, nearest to the center principle, nearest to the boundary principle and gravity principle; The second one deals with part of samples in BND, i.e., the samples which satisfy some conditions are dealt with, and the rest samples are still in the BND. The second method promotes the accuracy. This paper compares the two methods on five datasets using 10-fold cross-validation. The experimental results show that the effect and accuracy of dealing with part of samples in BND are better than those of dealing with all samples in BND.

Key words: constructive covering algorithm (CCA), dealing with samples in boundary regions, three-way decisions