License: Creative Commons Attribution 4.0 International license (CC BY 4.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.ICDT.2023.18
URN: urn:nbn:de:0030-drops-177602
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2023/17760/
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Feller, Thomas ; Lyon, Tim S. ; Ostropolski-Nalewaja, Piotr ; Rudolph, Sebastian

Finite-Cliquewidth Sets of Existential Rules: Toward a General Criterion for Decidable yet Highly Expressive Querying

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LIPIcs-ICDT-2023-18.pdf (0.9 MB)

Abstract

In our pursuit of generic criteria for decidable ontology-based querying, we introduce finite-cliquewidth sets (fcs) of existential rules, a model-theoretically defined class of rule sets, inspired by the cliquewidth measure from graph theory. By a generic argument, we show that fcs ensures decidability of entailment for a sizable class of queries (dubbed DaMSOQs) subsuming conjunctive queries (CQs). The fcs class properly generalizes the class of finite-expansion sets (fes), and for signatures of arity ≤ 2, the class of bounded-treewidth sets (bts). For higher arities, bts is only indirectly subsumed by fcs by means of reification. Despite the generality of fcs, we provide a rule set with decidable CQ entailment (by virtue of first-order-rewritability) that falls outside fcs, thus demonstrating the incomparability of fcs and the class of finite-unification sets (fus). In spite of this, we show that if we restrict ourselves to single-headed rule sets over signatures of arity ≤ 2, then fcs subsumes fus.

BibTeX - Entry

@InProceedings{feller_et_al:LIPIcs.ICDT.2023.18,
  author =	{Feller, Thomas and Lyon, Tim S. and Ostropolski-Nalewaja, Piotr and Rudolph, Sebastian},
  title =	{{Finite-Cliquewidth Sets of Existential Rules: Toward a General Criterion for Decidable yet Highly Expressive Querying}},
  booktitle =	{26th International Conference on Database Theory (ICDT 2023)},
  pages =	{18:1--18:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-270-9},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{255},
  editor =	{Geerts, Floris and Vandevoort, Brecht},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/opus/volltexte/2023/17760},
  URN =		{urn:nbn:de:0030-drops-177602},
  doi =		{10.4230/LIPIcs.ICDT.2023.18},
  annote =	{Keywords: existential rules, TGDs, cliquewidth, treewidth, bounded-treewidth sets, finite-unification sets, first-order rewritability, monadic second-order logic, datalog}
}

Keywords: existential rules, TGDs, cliquewidth, treewidth, bounded-treewidth sets, finite-unification sets, first-order rewritability, monadic second-order logic, datalog
Collection: 26th International Conference on Database Theory (ICDT 2023)
Issue Date: 2023
Date of publication: 17.03.2023

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