License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.ICDT.2016.22
URN: urn:nbn:de:0030-drops-57912
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2016/5791/
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Kröll, Markus ; Pichler, Reinhard ; Skritek, Sebastian

On the Complexity of Enumerating the Answers to Well-designed Pattern Trees

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Abstract

Well-designed pattern trees (wdPTs) have been introduced as an extension of conjunctive queries to allow for partial matching - analogously to the OPTIONAL operator of the semantic web query language SPARQL. Several computational problems of wdPTs have been studied in recent years, such as the evaluation problem in various settings, the counting problem, as well as static analysis tasks including the containment and equivalence problems. Also restrictions needed to achieve tractability of these tasks have been proposed. In contrast, the problem of enumerating the answers to a wdPT has been largely ignored so far. In this work, we embark on a systematic study of the complexity of the enumeration problem of wdPTs. As our main result, we identify several tractable and intractable cases of this problem both from a classical complexity point of view and from a parameterized complexity point of view.

BibTeX - Entry

@InProceedings{krll_et_al:LIPIcs:2016:5791,
  author =	{Markus Kr{\"o}ll and Reinhard Pichler and Sebastian Skritek},
  title =	{{On the Complexity of Enumerating the Answers to Well-designed Pattern Trees}},
  booktitle =	{19th International Conference on Database Theory (ICDT 2016)},
  pages =	{22:1--22:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-002-6},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{48},
  editor =	{Wim Martens and Thomas Zeume},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2016/5791},
  URN =		{urn:nbn:de:0030-drops-57912},
  doi =		{10.4230/LIPIcs.ICDT.2016.22},
  annote =	{Keywords: SPARQL, Pattern Trees, CQs, Enumeration, Complexity}
}

Keywords: SPARQL, Pattern Trees, CQs, Enumeration, Complexity
Collection: 19th International Conference on Database Theory (ICDT 2016)
Issue Date: 2016
Date of publication: 14.03.2016

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