Query answering in description logics with transitive roles

  • Authors:

  • Thomas Eiter;Carsten Lutz;Magdalena Ortiz;Mantas Šimkus

  • Affiliations:

  • Institute of Information Systems, Vienna University of Technology, Austria;Fachbereich Mathematik und Informatik, Universität Bremen, Germany;Institute of Information Systems, Vienna University of Technology, Austria;Institute of Information Systems, Vienna University of Technology, Austria

  • Venue:
  • IJCAI'09 Proceedings of the 21st international jont conference on Artifical intelligence
  • Year:
  • 2009

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Abstract

We study the computational complexity of conjunctive query answering w.r.t. ontologies formulated in fragments of the description logic SHIQ. Our main result is the identification of two new sources of complexity: the combination of transitive roles and role hierarchies which results in 2-EXPTIME-hardness, and transitive roles alone which result in CO-NEXPTIME-hardness. These bounds complement the existing result that inverse roles make query answering in SHIQ 2-EXPTIME-hard. We also show that conjunctive query answering with transitive roles, but without inverse roles and role hierarchies, remains in EXPTIME if the ABox is tree-shaped.