Dominance-based multi-granulation rough sets and decision rules extraction in incomplete fuzzy information systems

Multi-granulation rough set (MGRS) is a new research direction of rough set theory in recent years. This paper introduces the MGRS into the incomplete fuzzy information systems based on dominance relation. A model of dominance-based multi-granulation rough set (DMGRS) is established. Then a number of important properties are obtained. Moreover, a conclusion is presented by comparing the approximation accuracy between single granulation space and multi-granulation space, which indicates that the approximation accuracy will enlarge as the number of granulations increasing. Finally, three forms of “OR” decision rules are investigated.