SPARQL queries on RDF with fuzzy constraints and preferences

With the widespread acceptance of RDF (Resource Description Framework) as the de-facto standard recommended by W3C (World Wide Web Consortium) for the representation and exchange of information on the Web, a huge amount of RDF data is being proliferated and becoming available. Efficient querying of RDF data is therefore of increasing importance. Preference queries and fuzzy queries are required for personalized queries, and have been extensively investigated in the context of databases. Focusing on SPARQL (Simple Protocol and RDF Query Language), we propose a fuzzy extension of SPARQL with preferences in this paper. First, we extend SPARQL with fuzzy sets by allowing the occurrence of fuzzy terms, fuzzy operators and fuzzy relations. Second, we introduce multi-dimensional preferences into the fuzzy SPARQL. Based on fuzzy set theory, we also propose a set of translation rules to convert the fuzzy SPARQL with preferences into crisp SPARQL. Finally we propose an effective scoring function to calculate the order of query results, which integrates the preferences and membership degrees. The proposed approach is evaluated with experiments as well.