Semantics and Complexity of SPARQL

Jorge Pérez¹, Marcelo Arenas², and Claudio Gutierrez³

¹Universidad de Talca, Chile

²Pontificia Universidad Católica de Chile, Chile

³Universidad de Chile, Chile

Abstract. SPARQL is the W3C candidate recommendation query language for RDF. In this paper we address systematically the formal study of SPARQL, concentrating in its graph pattern facility. We consider for this study simple RDF graphs without special semantics for literals and a simplified version of filters which encompasses all the main issues. We provide a compositional semantics, prove there are normal forms, prove complexity bounds, among others that the evaluation of SPARQL patterns is PSPACE-complete, compare our semantics to an alternative operational semantics, give simple and natural conditions when both semantics coincide and discuss optimization procedures.

LNCS 4273, p. 30 ff.

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