Navigational queries as property path queries employing the Kleene star operator

Abstract

In the context of SPARQL, queries could be seen as patterns that are matched against an RDF graph. Until recently, it was not possible to create a pattern without specifying the exact path of the underlying graph (in terms of real data and/or variables) that would match against the graph. The advent of SPARQL 1.1 introduced property paths as a new graph matching paradigm that allows the employment of Kleene star * (and it's variant +) unary operators to build SPARQL queries that are agnostic of the underlying RDF graph structure. In this paper, we propose a generic SPARQL rewriting method that facilitates the execution of property path queries employing Kleene star * (and it's variant +) unary operators. This method is further extended through the employment of the RDF-Type Summary graph in an effort to reduce query execution time. The proposed approach is accordingly evaluated in terms of scalability with promising results.