Complexity of Inconsistency-Tolerant Query Answering in Datalog+/–

  • Thomas Lukasiewicz
  • Maria Vanina Martinez
  • Gerardo I. Simari
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8185)


The study of inconsistency-tolerant semantics for query answering in ontological languages has recently gained much attention. In this work, we consider three inconsistency-tolerant semantics recently proposed in the literature, namely: consistent query answering, the intersection (also called IAR) semantics, and the intersection of closed repairs (ICR) semantics. We study the data complexity of conjunctive query answering under these semantics for a wide set of tractable fragments of Datalog+/–. The Datalog+/– family of ontology languages covers several important description logics (DLs), bridging the gap in expressive power between database query languages and DLs as ontology languages, and extending the well-known Datalog language in order to embed DLs. Its properties of decidability of query answering and of tractability of query answering in the (data) complexity make Datalog+/– very useful in modeling real-world applications in which inconsistency-tolerant reasoning is essential.


Description Logic Dependency Graph Conjunctive Query Query Answering Consistent Answer 
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 2013

Authors and Affiliations

  • Thomas Lukasiewicz
    • 1
  • Maria Vanina Martinez
    • 1
  • Gerardo I. Simari
    • 1
  1. 1.Department of Computer ScienceUniversity of OxfordUK

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