One of the main results of the paper is a characterization of certain kind similarity relations in Pawlak knowledge representation systems by means of first order sentences. As an application we obtain a complete finite axiomatization of the corresponding poly modal logic, called in the paper MLSim. It is proved that MLSim possesses finite model property and is decidable.
Knowledge-based systems have become widespread in modern years. Knowledge-base developers need to be able to share and reuse knowledge bases that they build. As a result, interoperability among different knowledge-representation systems is essential. Domain ontology seeks to reduce conceptual and terminological confusion among users who need to share various kind of information. This paper shows how these structures make it possible to bridge the gap between standard objects and Knowledge-based Systems.