Gottlob, G., Pieris, A., & Šimkus, M. (2018). The Impact of Active Domain Predicates on Guarded Existential Rules. Fundamenta Informaticae, 159(1–2), 123–146. https://doi.org/10.3233/fi-2018-1660
E192-02 - Forschungsbereich Databases and Artificial Intelligence
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Journal:
Fundamenta Informaticae
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ISSN:
0169-2968
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Date (published):
2018
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Number of Pages:
24
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Publisher:
IOS Press
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Peer reviewed:
Yes
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Keywords:
Theoretical Computer Science; Information Systems; Algebra and Number Theory; Computational Theory and Mathematics; complexity; conjunctive queries; tuple-generating dependencies; expressive power; Rule-based languages; ontology-mediated queries; existential rules; guardedness
en
Abstract:
It is realistic to assume that a database management system provides access to the active domain via built-in relations. Therefore, databases that include designated predicates that hold the active domain, which we call product databases, form a natural notion that deserves our attention. An important issue then is to look at the consequences of product databases for the expressiveness and complexity of central existential rule languages. We focus on guarded-based existential rules, and we investigate the impact of product databases on their expressive power and complexity. We show that the queries expressed via (frontier-)guarded rules gain in expressiveness, and in fact, they have the same expressive power as Datalog. On the other hand, there is no impact on the expressiveness of the queries specified via weakly-(frontier-)guarded rules since they are powerful enough to explicitly compute the predicates needed to access the active domain. We also observe that there is no impact on the complexity of the query languages in question.
