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On the Problem of Computing Small Representations of Least Common Subsumers

  • Franz Baader
  • Anni-Yasmin Turhan
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2479)

Abstract

For Description Logics with existential restrictions, the size of the least common subsumer (lcs) of concept descriptions may grow exponentially in the size of the input descriptions. The first (negative) result presented in this paper is that it is in general not possible to express the exponentially large concept description representing the lcs in a more compact way by using an appropriate (acyclic) terminology. In practice, a second and often more severe cause of complexity was the fact that concept descriptions containing concepts defined in a terminology must first be unfolded (by replacing defined names by their definition) before the known lcs algorithms could be applied. To overcome this problem, we present a modified lcs algorithm that performs lazy unfolding, and show that this algorithm works well in practice.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Franz Baader
    • 1
  • Anni-Yasmin Turhan
    • 1
  1. 1.Theoretical Computer ScienceTU DresdenGermany

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