The path index for query processing on RDF and RDF schema

In the semantic Web, metadata and ontology plays important roles for advanced information retrieval systems. A large amount of RDF documents for describing metadata and RDF Schema documents for representing ontology is made available. Therefore, many studies to store and query metadata and ontology in RDF and RDF Schema are required. Unlike XML, RDF and RDF Schema express information resources and semantic associations between resources on the Web. And these documents can be represented based on graph model. To retrieve efficiently RDF data, the schematic information defined by RDF Schema and methods for querying by using path expressions are required. For these necessities, we define query patterns to retrieve RDF data in RDF and RDF Schema. Then for retrieving those query patterns efficiently, we extract path expressions in RDF and RDF Schema graph models and construct indexing structures based on path expressions