A Simple Modal Logic for Reasoning in Multigranulation Rough Set Model

The notions of strong/weak approximations have been studied extensively in recent years. These approximations are based on a structure of the form (W, {R-i}(i is an element of N)), called the multiple-source approximation system, where R-i is an equivalence relation on W, and N is an initial segment of the set N of natural numbers. We propose and explore a simple modal language and semantics that can be used to reason about the strong/weak approximations of concepts. Moreover, our study is not confined to collections of equivalence relations only, but other types of relations are also considered. This study is important, keeping in view the notions of generalized approximation spaces with relations other than equivalence.