Ontology Mapping and SPARQL Rewriting for Querying Federated RDF Data Sources - (Short Paper)

The web of data consists of distributed, diverse (in terms of schema adopted), and large RDF datasets. In this paper we present a SPARQL query rewriting method which can be used to achieve interoperability in semantic information retrieval and/or knowledge discovery processes over interconnected RDF data sources. Formal mappings between different overlapping ontologies are exploited in order to rewrite initial user SPARQL queries, so that they can be evaluated over different RDF data sources on different sites. The proposed environment is utilized by an ontology-based mediator system, which we have developed in order to provide data integration within the Semantic Web environment.