Constrained regular expressions for answering RDF-path queries modulo RDFS

The standard SPARQL query language is currently defined for querying RDF graphs without RDFS semantics. Several extensions to SPARQL have been proposed to query RDF graphs considering RDFS semantics. In this paper, we discuss extensions of SPARQL that uses regular expressions to navigate RDF graphs and may be used to answer queries considering RDFS semantics. In particular, we present and compare nSPARQL and our proposal CPSPARQL. We show that CPSPARQL is expressive enough to answer full SPARQL queries modulo RDFS. Finally, we compare the expressiveness and complexity of both nSPARQL and the corresponding fragment of CPSPARQL, that we call cpSPARQL. We show that both languages have the same complexity through cpSPARQL, being a proper extension of SPARQL graph patterns, is more expressive than nSPARQL.