Skip to Main content Skip to Navigation
New interface
Conference papers

The Complexity of Ontology-Based Data Access with OWL 2 QL and Bounded Treewidth Queries

Abstract : Our concern is the overhead of answering OWL 2 QL ontology-mediated queries (OMQs) in ontology-based data access compared to evaluating their underlying tree-shaped and bounded treewidth conjunctive queries (CQs). We show that OMQs with bounded-depth ontologies have nonrecursive datalog (NDL) rewritings that can be constructed and evaluated in LOGCFL for combined complexity, even in NL if their CQs are tree-shaped with a bounded number of leaves, and so incur no overhead in complexity-theoretic terms. For OMQs with arbitrary ontologies and bounded-leaf CQs, NDL-rewritings are constructed and evaluated in LOGCFL. We show experimentally feasibility and scalability of our rewritings compared to previously proposed NDL-rewritings. On the negative side, we prove that answering OMQs with tree-shaped CQs is not fixed-parameter tractable if the ontology depth or the number of leaves in the CQs is regarded as the parameter, and that answering OMQs with a fixed ontology (of infinite depth) is NP-complete for tree-shaped and LOGCFL for bounded-leaf CQs.
Complete list of metadata

Cited literature [60 references]  Display  Hide  Download
Contributor : Meghyn Bienvenu Connect in order to contact the contributor
Submitted on : Friday, November 10, 2017 - 2:40:38 PM
Last modification on : Friday, August 5, 2022 - 3:03:00 PM
Long-term archiving on: : Sunday, February 11, 2018 - 2:00:40 PM


Files produced by the author(s)


  • HAL Id : hal-01632638, version 1



Meghyn Bienvenu, Stanislav Kikot, Roman Kontchakov, Vladimir V Podolskii, Vladislav Ryzhikov, et al.. The Complexity of Ontology-Based Data Access with OWL 2 QL and Bounded Treewidth Queries. PODS: Principles of Database Systems, Jun 2017, Chicago, United States. ⟨hal-01632638⟩



Record views


Files downloads