| Article ID: | iaor20122327 |
| Volume: | 59 |
| Issue: | 1 |
| Start Page Number: | 431 |
| End Page Number: | 436 |
| Publication Date: | Jan 2010 |
| Journal: | Computers and Mathematics with Applications |
| Authors: | Wang Changzhong, Chen Degang |
| Keywords: | group decision making |
It is a useful method in research of group theory to construct a new group by using known groups. Lower and upper approximation operators of rough sets are applied into group theory and so the notion of a rough group has been introduced. In this paper, we first point out that there are still some incomplete propositions in Kuroki and Wang (1996) although some authors have showed several incorrect statements in the literature. We then present improved versions of the incomplete propositions and continue to study the image and inverse image of rough approximations of a subgroup with respect to a homomorphism between two groups.