2 research outputs found
An extension of SPARQL for expressing qualitative preferences
In this paper we present SPREFQL, an extension of the SPARQL language that
allows appending a PREFER clause that expresses "soft" preferences over the
query results obtained by the main body of the query. The extension does not
add expressivity and any SPREFQL query can be transformed to an equivalent
standard SPARQL query. However, clearly separating preferences from the "hard"
patterns and filters in the WHERE clause gives queries where the intention of
the client is more cleanly expressed, an advantage for both human readability
and machine optimization. In the paper we formally define the syntax and the
semantics of the extension and we also provide empirical evidence that
optimizations specific to SPREFQL improve run-time efficiency by comparison to
the usually applied optimizations on the equivalent standard SPARQL query.Comment: Accepted to the 2017 International Semantic Web Conference, Vienna,
October 201
SPARQL with Qualitative and Quantitative Preferences Position Paper
Abstract. The volume and diversity of data that is queriable via SPARQL and its increasing integration motivate the desire to query SPARQL information sources via the specification of preferred query outcomes. Such preference-based queries support the ordering of query outcomes with respect to a user’s measure of the quality of the response. In this position paper we argue for the incorporation of preference queries into SPARQL. We propose an extension to the SPARQL query language that supports the specification of qualitative and quantitative preferences over query outcomes and examine the realization of the resulting preferencebased queries via off-the-shelf SPARQL engines.