Using Rough Set Theory for Reasoning on Vague Ontologies

Web ontologies can contain vague concepts, which means the knowledge about them is imprecise and then query answering will not possible due to open world assumption. A concept description be very exact (crisp concept) or (fuzzy if its complete, otherwise it inexact (vague incomplete. In this paper, we propose a method based on rough set theory for reasoning ontologies. With method, detection of concepts insert into original ontology new where their defined approximation spaces used by extended Tableau algorithm automatic reasoning. prototype Tableau's developed tested examples encouraging results are given demonstrate that unlike other methods, answer queries even in presence incomplete information.