Paper 181 (Research track)

The Problem of Correlation and Substitution in SPARQL

Author(s): Daniel Hernandez, Claudio Gutierrez, Renzo Angles

Abstract: Implementations of a standard language are expected to give same outputs to identical queries. In this paper we study why different implementations of SPARQL (Fuseki, Virtuoso, Blazegraph and rdf4j) behave differently when evaluating queries with correlated variables. We show that at the core of this problem lies the historically troubling notion of logical substitution. We present a formal framework to study this issue based on Datalog that besides clarifying the problem, gives a solid base to define and implement nesting.

Keywords: Correlation; Substitution; SPARQL

Share on

Leave a Reply

Your email address will not be published. Required fields are marked *