Reliable Semantics for Extended Logic Programs with Rule Prioritization

Abstract

We present a new semantics for extended logic programs with rule prioritization (EP P ). The semantics, called reliable semantics (RS), generalizes the well-founded semantics which is defined for normal programs [34]. It also generalizes the extended well-founded semantics which is defined for non-contradictory extended programs [24]. Because of the classical negation in the head of the rules, the well-founded model of a program can be contradictory. RS is contradiction-free and defined for all EP P s. To avoid contradictions, only reliable rules and reliable closed world assumptions are used in the fixpoint computation of RS. A closed world assumption (CW A) is considered reliable if it is not "suspect" for any constraint violation. A rule r is considered reliable if it is not "suspect" for any constraint violation caused by rules with priority no lower than r. We define the stable r-models of an EP P and we show that the RS of a program coincides with its least stable r-model. The RS of an EP P , P , represents the skeptical "meaning" of P whereas stable r-models of P represent the possible "meanings" of P .

Using methods of declarative logic programming for intelligent information agents

“…They have quite different foundations such as logical entrenchment and specificity (Nute, 1994), reliability handling (Analyti & Pramanik, 1995), well-founded semantics (Brewka, 1996), or defeasible argumentation (Prakken & Sartor, 1997).…”

“…Further semantics for priorities in extended logic programming, which are not based on answer sets, have been proposed in (Nute, 1994;Analyti & Pramanik, 1995;Brewka, 1996;Prakken & Sartor, 1997). They have quite different foundations such as logical entrenchment and specificity (Nute, 1994), reliability handling (Analyti & Pramanik, 1995), well-founded semantics (Brewka, 1996), or defeasible argumentation (Prakken & Sartor, 1997).…”

Extending the expressiveness of fuzzy logic languages

“…THE SEMANTICS OF THE FRAMEWORK'S CONFIGURATION FILE been provided by a rule, by the combination of a rule and one or more default value assignments or just by one or more default value assignments. In the last one the authors introduce a priorities system closer to the one we have here, by taking ideas from some works in which the authors introduce priorities in logic programming (LP), as Wang, Zhou and Fangzhen in [WZL00], Analyti and Pramanik in [AP95], Laenens and Vermeir in [LV90], Marek, Nerode and Remmel in [MNR97], Jayaraman, Govindarajan and Mantha in [JGM07] and Delgrande, Schaub and Tompits in [DST03]. The differences between this work and the proposal of Pablos-Ceruelo and Muñoz-Hernández [PM11] are mainly due to the inclusion of modifiers and negation operators.…”