The Impact of Active Domain Predicates on Guarded Existential Rules

Georg Gottlob, Andreas Pieris, Mantas Simkus

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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, forma 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.
Original languageEnglish
Pages (from-to)123-146
Number of pages22
JournalFundamenta Informaticae
Issue number1-2
Publication statusPublished - 7 Mar 2018

Keywords / Materials (for Non-textual outputs)

  • Rule-based languages
  • ontology-mediated queries
  • conjunctive queries
  • existential rules
  • tuple-generating dependencies
  • guardedness
  • expressive power
  • Complexity


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