Ontology-Based Data Access: A Study through Disjunctive Datalog, CSP, and MMSNP

• Autores: Meghyn Bienvenu, Balder Ten Cate, Carsten Lutz, Frank Wolter
• Localización: ACM transactions on database systems, ISSN 0362-5915, Vol. 39, Nº 4 ( Invited Articles Issue, SIGMOD 2013, PODS 2013 and ICDT ), 2014
• Idioma: inglés
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• Resumen

  • Ontology-based data access is concerned with querying incomplete data sources in the presence of domain-specific knowledge provided by an ontology. A central notion in this setting is that of an ontology-mediated query, which is a database query coupled with an ontology. In this article, we study several classes of ontology-mediated queries, where the database queries are given as some form of conjunctive query and the ontologies are formulated in description logics or other relevant fragments of first-order logic, such as the guarded fragment and the unary negation fragment. The contributions of the article are threefold. First, we show that popular ontology-mediated query languages have the same expressive power as natural fragments of disjunctive datalog, and we study the relative succinctness of ontology-mediated queries and disjunctive datalog queries. Second, we establish intimate connections between ontology-mediated queries and constraint satisfaction problems (CSPs) and their logical generalization, MMSNP formulas. Third, we exploit these connections to obtain new results regarding: (i) first-order rewritability and datalog rewritability of ontology-mediated queries; (ii) P/NP dichotomies for ontology-mediated queries; and (iii) the query containment problem for ontology-mediated queries.