On the Relationship between Shy and Warded Datalog+/-

TL;DR

This paper explores the relationship between Shy and Warded Datalog+/- fragments, which are promising for query answering over expressive Datalog^E, and provides an experimental comparison of systems implementing these fragments.

Contribution

It clarifies the relationship between Shy and Warded Datalog+/- fragments and compares their implementations through experimental analysis.

Findings

Shy and Warded Datalog+/- are promising for decidable query answering.

Experimental results compare DLV^E and Vadalog systems.

Insights into the practical performance of these fragments.

Abstract

Datalog^E is the extension of Datalog with existential quantification. While its high expressive power, underpinned by a simple syntax and the support for full recursion, renders it particularly suitable for modern applications on knowledge graphs, query answering (QA) over such language is known to be undecidable in general. For this reason, different fragments have emerged, introducing syntactic limitations to Datalog^E that strike a balance between its expressive power and the computational complexity of QA, to achieve decidability. In this short paper, we focus on two promising tractable candidates, namely Shy and Warded Datalog+/-. Reacting to an explicit interest from the community, we shed light on the relationship between these fragments. Moreover, we carry out an experimental analysis of the systems implementing Shy and Warded, respectively DLV^E and Vadalog.