Rough Set Method Based on Multi-Granulations

The original rough set model is concerned primarily with the approximation of sets described by single binary relation on universe. In the view of granular computing, classical rough set theory is researched by single granulation (static granulation). The article extends the Pawlak rough set model to rough set model based on multi-granulations MGRS, where the set approximations are defined by using multi-equivalences on the universe. Mathematical properties of MGRS are investigated. It is shown that some properties of Pawlak rough set are special instances of MGRS, approximation measure of set described by using multi-granulations is always better than by using single granulation, which is suitable for describing more accurately the concept and solving problem according to user requirement

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