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DOI: 10.4230/LIPIcs.ICDT.2015.195
URN: urn:nbn:de:0030-drops-49856
URL: http://drops.dagstuhl.de/opus/volltexte/2015/4985/
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Staworko, Slawek ; Boneva, Iovka ; Labra Gayo, Jose E. ; Hym, Samuel ; Prud'hommeaux, Eric G. ; Solbrig, Harold

Complexity and Expressiveness of ShEx for RDF

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Abstract

We study the expressiveness and complexity of Shape Expression Schema (ShEx), a novel schema formalism for RDF currently under development by W3C. A ShEx assigns types to the nodes of an RDF graph and allows to constrain the admissible neighborhoods of nodes of a given type with regular bag expressions (RBEs). We formalize and investigate two alternative semantics, multi- and single-type, depending on whether or not a node may have more than one type. We study the expressive power of ShEx and study the complexity of the validation problem. We show that the single-type semantics is strictly more expressive than the multi-type semantics, single-type validation is generally intractable and multi-type validation is feasible for a small (yet practical) subclass of RBEs. To curb the high computational complexity of validation, we propose a natural notion of determinism and show that multi-type validation for the class of deterministic schemas using single-occurrence regular bag expressions (SORBEs) is tractable.

BibTeX - Entry

@InProceedings{staworko_et_al:LIPIcs:2015:4985,
  author =	{Slawek Staworko and Iovka Boneva and Jose E. Labra Gayo and Samuel Hym and Eric G. Prud'hommeaux and Harold Solbrig},
  title =	{{Complexity and Expressiveness of ShEx for RDF}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{195--211},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Marcelo Arenas and Mart{\'i}n Ugarte},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2015/4985},
  URN =		{urn:nbn:de:0030-drops-49856},
  doi =		{10.4230/LIPIcs.ICDT.2015.195},
  annote =	{Keywords: RDF, Schema, Graph topology, Validation, Complexity, Expressiveness}
}

Keywords: RDF, Schema, Graph topology, Validation, Complexity, Expressiveness
Seminar: 18th International Conference on Database Theory (ICDT 2015)
Issue Date: 2015
Date of publication: 19.03.2015


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