@inproceedings{4a4d84d6ab404f79843939284360e171,
title = "Complexity and expressiveness of ShEx for RDF",
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, 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.",
keywords = "Complexity, Expressiveness, Graph topology, RDF, Schema, Validation",
author = "S{\l}awek Staworko and Iovka Boneva and {Labra Gayo}, {Jose E.} and Samuel Hym and Prud'hommeaux, {Eric G.} and Harold Solbrig",
year = "2015",
month = jan,
day = "1",
doi = "10.4230/LIPIcs.ICDT.2015.195",
language = "English (US)",
series = "Leibniz International Proceedings in Informatics, LIPIcs",
publisher = "Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing",
pages = "195--211",
editor = "Marcelo Arenas and Martin Ugarte",
booktitle = "18th International Conference on Database Theory, ICDT 2015",
address = "Germany",
note = "18th International Conference on Database Theory, ICDT 2015 ; Conference date: 23-03-2015 Through 27-03-2015",
}