Complex quantified formulas in SPARQL 1.1: formalisation, translation, and partial verbalisation
Anastasia Analyti · International Journal of Web Engineering and Technology · 2023
In this paper, we propose quantified SPARQL 1.1 filter expressions, called also q-SPARQL filter expressions for short, based on a specific grammar that uses not only EXISTS and NOT EXISTS keywords but also FORALL-IMPLIES. These filter expressions is a syntactic sugar to SPARQL 1.1 filter expressions since they have a translation to them. However through various examples, we demonstrate their user-friendliness. Additionally, we formally define q-SPARQL queries which use q-SPARQL filter expressions. We further analyse which variables of q-SPARQL filter expressions are universally quantified and which are existential. We also indicate the places where these variables can appear. We translate two nested NOT EXISTS filter expressions into FORALL-IMPLIES form, when it is possible, improving user friendliness of the query. Finally, we partially verbalise q-SPARQL filter expressions, making easier their understanding from the user.