Semantics in Data and Knowledge Bases

Volume 4925 of the series Lecture Notes in Computer Science pp 199-214

Rewriting Conjunctive Queries over Description Logic Knowledge Bases

  • Héctor Pérez-UrbinaAffiliated withComputing Laboratory, University of Oxford
  • , Boris MotikAffiliated withComputing Laboratory, University of Oxford
  • , Ian HorrocksAffiliated withComputing Laboratory, University of Oxford

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We consider the problems of conjunctive query answering and rewriting for information integration systems in which a Description Logic ontology is used to provide a global view of the data. We present a resolution-based query rewriting algorithm for DL-Lite +  ontologies, and use it to show that query answering in this setting is NLogSpace-complete with respect to data complexity. We also show that our algorithm produces an optimal rewriting when the input ontology is expressed in the language DL-Lite. Finally, we sketch an extended version of the algorithm that would, we are confident, be optimal for several DL languages with data complexity of query answering ranging from LogSpace to PTime-complete.