A fuzzy extension of SPARQL based on fuzzy sets and aggregators

SPARQL has been adopted as query language for the Semantic Web. RDF and OWL have also been established as vocabularies to describe ontologies in this setting. While RDF/OWL/SPARQL have been designed for querying crisp information, some contexts require to manage uncertainty, vagueness and imprecise knowledge. In this paper a SPARQL extension, called FSA-SPARQL (Fuzzzy Sets and Aggregators based SPARQL) is proposed, in which queries can involve different fuzzy connectives and (aggregation) operators. The language has been implemented as an extension of the ARQ Jena SPARQL engine and it is equipped with a Web tool from which queries can be executed on-line.