Rough set model under a limited asymmetric similarity relation and an approach for incremental updating approximations

The rough set model under the asymmetric similarity relation is an extension of classical rough set model under equivalence relation, by which incomplete information systems can be dealt with effectively. In this paper, a new extension model of rough set under a kind of limited asymmetric similarity relation is proposed firstly, and then by providing four theorems on incremental updating approximations and their proofs, an approach for incremental updating approximations is presented under the limited asymmetric similarity relation when the attribute set is dynamically changing in incomplete information systems. Finally, An illustrative example is given to verify the validity of the proposed method. Moreover, it may be used to support dynamic knowledge discovery.