Capturing Stationary and Regular Extensions with Reiter's Extensions

  • Authors:
  • Tomi Janhunen

  • Affiliations:
  • -

  • Venue:
  • JELIA '00 Proceedings of the European Workshop on Logics in Artificial Intelligence
  • Year:
  • 2000

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Abstract

Janhunen et al. [14] have proposed a translation technique for normal logic programs in order to capture the alternating fix-points of a program with the stable models of the translation. The same technique is also applicable in the disjunctive case so that partial stable models can be captured. In this paper, the aim is to capture Przymusinska and Przymusinski's stationary extensions with Reiter's extensions using the same translational idea. The resulting translation function is polynomial, but only weakly modular and not perfectly faithful. Fortunately, another technique leads to a polynomial, faithful and modular (PFM) translation function. As a result, stationary default logic (STDL) is ranked in the expressive power hierarchy (EPH) of non-monotonic logics [13]. Moreover, reasoning with stationary extensions as well as brave reasoning with regular extensions (i.e., maximal stationary extensions) can be implemented using an inference engine for reasoning with Reiter's extensions.