Lower and Upper Approximations in Hv- groups

The purpose of this paper is to introduce and discuss the concept of lower and upper approximations. A simple and straightforward way for interpreting rough sets is to use membership functions. We investi-gate the similarity between rough membership function and conditional probability. We also consider the fundamental relation kr defined on an Hy-group H and interprets the lower and upper approximations as sub-sets of the group Hi/` and give some properties of such subsets.