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A General Datalog-Based Framework for Tractable Query Answering Over Ontologies

79 Pages Posted: 22 Jun 2018 Publication Status: Accepted

See all articles by Andrea Cali

Andrea Cali

University of London - Department of Computer Science & Information Systems; University of Oxford - Oxford-Man Institute of Quantitative Finance

Georg Gottlob

University of Oxford - Department of Computer Science; University of Oxford - Oxford-Man Institute of Quantitative Finance

Thomas Lukasiewicz

University of Oxford - Computing Laboratory

Abstract

Ontologies and rules play a central role in the development of the Semantic Web. Recent research in this context focuses especially on highly scalable formalisms for the Web of Data, which may highly benefit from exploiting database technologies. In this paper, as a first step towards closing the gap between the Semantic Web and databases, we introduce a family of expressive extensions of Datalog, called Datalog±, as a new paradigm for query answering over ontologies. The Datalog± family admits existentially quantified variables in rule heads, and has suitable restrictions to ensure highly efficient ontology querying. We show in particular that Datalog± encompasses and generalizes the tractable description logic ℇ 𝓛 and the DL-Lite family of tractable description logics, which are the most common tractable ontology languages in the context of the Semantic Web and databases. We also show how stratified negation can be added to Datalog± while keeping ontology querying tractable. Furthermore, the Datalog± family is of interest in its own right, and can, moreover, be used in various contexts such as data integration and data exchange. It paves the way for applying results from databases to the context of the Semantic Web.

Keywords: Datalog, Ontologies, Semantic Web, Dl-Lite, OWL, Conjunctive Queries, Query Evaluation, Chase, Dependencies, Constraints, Complexity, Tractability

Suggested Citation

Cali, Andrea and Gottlob, Georg and Lukasiewicz, Thomas, A General Datalog-Based Framework for Tractable Query Answering Over Ontologies (2012). Journal of Web Semantics First Look 14_0_1, Available at SSRN: https://ssrn.com/abstract=3198957 or http://dx.doi.org/10.2139/ssrn.3198957

Andrea Cali

University of London - Department of Computer Science & Information Systems ( email )

Malet Street, Bloomsbury
London
United Kingdom

University of Oxford - Oxford-Man Institute of Quantitative Finance

Eagle House
Walton Well Road
Oxford, Oxfordshire OX2 6ED
United Kingdom

Georg Gottlob

University of Oxford - Department of Computer Science ( email )

Wolfson Building, Parks Road
Oxford
United Kingdom

University of Oxford - Oxford-Man Institute of Quantitative Finance

Eagle House
Walton Well Road
Oxford, Oxfordshire OX2 6ED
United Kingdom

Thomas Lukasiewicz (Contact Author)

University of Oxford - Computing Laboratory ( email )

Wolfson Building
Parks Road
Oxford, OX1 3QD
United Kingdom

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