A Context-Based Semantics for SPARQL Property Paths over the Web

Presented at: The 12th Extented Semantic Web Conference (ESWC2015)

by Olaf Hartig, Giuseppe PirrĂ²

As of today, there exists no standard language for querying Linked Data on the Web, where navigation across distributed data sources is a key feature. A natural candidate seems to be SPARQL, which recently has been enhanced with navigational capabilities thanks to the introduction of property paths (PPs). However, the semantics of SPARQL restricts the scope of navigation via PPs to single RDF graphs. This restriction limits the applicability of PPs on the Web. To fill this gap, in this paper we provide formal foundations for evaluating PPs on the Web, thus contributing to the definition of a query language for Linked Data. In particular, we introduce a query semantics for PPs that couples navigation at the data level with navigation on the Web graph. Given this semantics we find that for some PP-based SPARQL queries a complete evaluation on the Web is not feasible. To enable systems to identify queries that can be evaluated completely, we establish a syntactic and, thus, decidable property of such queries.

Keywords: SPARQL, Navigation, Property Paths, Theory, Linked Data

Resource URI on the dog food server: http://data.semanticweb.org/conference/eswc/2015/paper/research/132

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