Is non-monotonic reasoning always harder

  • Uwe Egly
  • Hans Tompits
Regular Papers
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1265)


Although it has been shown that non-monotonic reasoning is presumably harder than classical reasoning, there are cases where a non-monotonic treatment actually simplifies matters. Indeed, one of the reasons for considering non-monotonic systems is the hope of speeding up reasoning, and not to slow it down. In this paper, we consider proof lengths in a cut-free sequent calculus, and we show that the application of circumscription (or completion) to certain first-order formulae leads to a non-elementary speed-up of proof length. This is possible because the introduction of the completion formula can simulate the cut rule.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Uwe Egly
    • 1
  • Hans Tompits
    • 1
  1. 1.Technische Universität WienWienAustria

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