Petri Net Representation of Ontologies for Indoor Location- Based Services

Abstract

This paper presents a Petri net representation of an ontology for indoor location-based services. The ontology is described within the Resource Description Framework (RDF). Therefore, this paper proposes a method for transforming the RDF model into a CPN (colored Petri net). The proposed method represents the semantics of the RDF model in the CPN by mapping the classes and properties of the RDF model onto CPN places and representing the relationships between those classes and properties as token transitions in the CPN. To represent an RDF statement in the CPN, the method introduces a transition that produces a (complex) token composed of two ordered (simple) tokens: one corresponding to the subject and the other corresponding to the object of the statement. Applying the proposed method, we build a sample CPN for an RDF model and perform simulations using the model to answer RDF queries. This paper also introduces a simple ontology for an indoor location- based service. Using the proposed transformation method, we transform the ontology into a CPN. Finally, we introduce our inference algorithm for the CPN and a prototype database system for demonstrating the practicality of our method. The results indicate that the proposed database system can resolve the semantic ambiguities in the query by using the ontology.