Recently, SPARQL-DL was introduced in [7] as a rich query language for OWL-DL ontologies. It provides an OWL-DL-like semantics for SPARQL basic graph patterns which involves as special cases both conjunctive ABox queries and mixed TBox/RBox/ABox queries over Description Logic (DL) ontologies. This paper describes the implementation of a SPARQL-DL query engine and discusses several optimizations...

A W3C standard for processing RDF data is a SPARQL query language, a technique that is used to encode data in meaningful manner. We investigate the foundations of SPARQL query optimization by grouping into individual clusters using common substructures in the multiple SPARQL queries, propose a comprehensive set of query rewriting rules for the clustered group and finally Query execution provide...

This paper presents a thorough study of negation in SPARQL. The types of negation supported in SPARQL are identified and their main features discussed. Then, we study the expressive power of the corresponding negation operators. At this point, we identify a core SPARQL algebra which could be used instead of the W3C SPARQL algebra. Finally, we analyze the negation operators in terms of their com...

Until now, the sparql query language was restricted to simple entailment. Now sparql is being extended with more expressive entailment regimes. This allows to query over inferred, implicit knowledge. However, in this case the sparql endpoint provider decides which inference rules are used for its entailment regimes. In this paper, we propose an extension to the sparql query language to support ...

Represented knowledge is subject to frequent changes. To meet these requirements for dynamics, SPARQL update, an update language for RDF graphs, was developed. Even though there is some research on semantics of SPARQL ABox update for RDFS ontologies and approaches addressing updates in interplay with rather restricted TBoxes languages, up till now there is no definition of semantics for SPARQL ...