Dynamic maintenance of approximations based on variable precision rough sets

In real applications, information systems may vary with time due to different reasons. Approximations of a concept under variable precision rough sets (VPRS) will change when an information system changes. Usually, incremental updating methods are an effective way to maintenance knowledge in a dynamic environment. Algorithms for incremental updating approximations are proposed in this paper when objects are added into or deleted from the universe. Finally, an experimental evaluation validates the efficiency of the proposed methods that can be used for dynamic maintenance of approximations under VPRS with regard to a concept.