On the Interaction of Existential Rules and Equality Constraints in Ontology Querying

  • Andrea Calì
  • Georg Gottlob
  • Giorgio Orsi
  • Andreas Pieris
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7265)


Ontological query processing is an exciting research topic in database theory, knowledge representation, and logic programming. In many cases, ontological constraints are expressed over an extensional database by extending traditional Datalog rules to allow existential quantification and equality atoms in the head. The unrestricted use of these features causes undecidability of query answering and, therefore, their interaction must be controlled. This work provides a tutorial-like introduction to the problem of query answering under existential and equality constraints. We survey the most notable (semantic and syntactic) restrictions to such constraints ensuring decidability of query answering, and we discuss their practical application to conceptual modelling.


Equality Constraint Description Logic Conjunctive Query Query Answering Inclusion Dependency 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Andrea Calì
    • 2
    • 3
  • Georg Gottlob
    • 1
    • 3
    • 4
  • Giorgio Orsi
    • 1
    • 4
  • Andreas Pieris
    • 1
  1. 1.Department of Computer ScienceUniversity of OxfordUK
  2. 2.Dept. of Computer Science and Inf. SystemsBirkbeck University of LondonUK
  3. 3.Oxford-Man Institute of Quantitative FinanceUniversity of OxfordUK
  4. 4.Institute for the Future of ComputingOxford Martin SchoolUK

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