Constraints in RDF

  • Authors:

  • Waseem Akhtar;Álvaro Cortés-Calabuig;Jan Paredaens

  • Affiliations:

  • Vrije Universiteit Brussel, Belgium;University of Antwerp, Belgium;University of Antwerp, Belgium

  • Venue:
  • SDKB'10 Proceedings of the 4th international conference on Semantics in data and knowledge bases
  • Year:
  • 2010

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Abstract

RDF (Resource Description Framework) is a World Wide Web Consortium recommendation for specifying meta-data models on the web. RDF databases consist of triples in the form of subject-predicateobject, which are often conceptualized as defining a directed labeled graph. In this paper, we extend the basic model of RDF by introducing two types of integrity constraints, namely functional and equality generating constraints. Our formal framework is inspired and motivated by the importance of the corresponding constraints in the relational model. In the first part of the paper we present the formal notion of satisfaction for both types of constraints and introduce a mechanism to express functional constraints in terms of equality generating constraints, and we show that the converse is not possible. In the second part, we define an Armstrong-type scheme of rules for equality generating constraints and we prove that these rules form a sound and complete set. In addition, we present chase-like algorithms for both types of constraints that check whether a single constraint follows from a given set of constraints.