Complexity and expressiveness of ShEx for RDF

Sławek Staworko, Iovka Boneva, Jose E. Labra Gayo, Samuel Hym, Eric G. Prud'hommeaux, Harold Solbrig

Research output: Chapter in Book/Report/Conference proceedingConference contribution

21 Scopus citations


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, multiand 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.

Original languageEnglish (US)
Title of host publication18th International Conference on Database Theory, ICDT 2015
EditorsMarcelo Arenas, Martin Ugarte
PublisherSchloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
Number of pages17
ISBN (Electronic)9783939897798
StatePublished - Jan 1 2015
Externally publishedYes
Event18th International Conference on Database Theory, ICDT 2015 - Brussels, Belgium
Duration: Mar 23 2015Mar 27 2015

Publication series

NameLeibniz International Proceedings in Informatics, LIPIcs
ISSN (Print)1868-8969


Other18th International Conference on Database Theory, ICDT 2015


  • Complexity
  • Expressiveness
  • Graph topology
  • RDF
  • Schema
  • Validation

ASJC Scopus subject areas

  • Software


Dive into the research topics of 'Complexity and expressiveness of ShEx for RDF'. Together they form a unique fingerprint.

Cite this