Publications in Scientific Journals:
T. Eiter, Y. Shen:
"Evaluating epistemic negation in answer set programming";
Epistemic negation not along with default negation ¬ plays a key role in knowledge representation and nonmonotonic reasoning. However, the existing epistemic approaches such as those by Gelfond ,  and , Truszczynski  and Kahl et al.  behave not satisfactorily in that they suffer from the problems of unintended world views due to recursion through the epistemic modal operator K or M (KFKF and MFMF are shorthands for View the MathML source¬notF and not¬Fnot¬F, respectively). In this paper we present a new approach to handling epistemic negation which is free of unintended world views and thus offers a solution to the long-standing problem of epistemic specifications which were introduced by Gelfond  over two decades ago. We consider general logic programs consisting of rules of the form H←BH←B, where H and B are arbitrary first-order formulas possibly containing epistemic negation, and define a general epistemic answer set semantics for general logic programs by introducing a novel program transformation and a new definition of world views in which we apply epistemic negation to minimize the knowledge in world views. The general epistemic semantics is applicable to extend any existing answer set semantics, such as those defined in , , , , ,  and , with epistemic negation. For illustration, we extend FLP answer set semantics of Faber et al.  for general logic programs with epistemic negation, leading to epistemic FLP semantics. We also extend the more restrictive well-justified FLP semantics of Shen et al. , which is free of circularity for default negation, to an epistemic well-justified semantics. We consider the computational complexity of epistemic FLP semantics and show that for a propositional program Π with epistemic negation, deciding whether Π has epistemic FLP answer sets is View the MathML sourceΣ3p-complete and deciding whether a propositional formula F is true in Π under epistemic FLP semantics is View the MathML sourceΣ4p-complete in general, but has lower complexity for logic programs that match normal epistemic specifications, where the complexity of world view existence and query evaluation drops by one level in the polynomial hierarchy.
Answer set programming; Epistemic negation; Semantics
"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)
Electronic version of the publication:
Project Head Thomas Eiter:
Answer Set Programmierung für das Semant
Created from the Publication Database of the Vienna University of Technology.