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 .
Analyti and Pramanik. Yet another semantics for extended logic programs, called reliable semantics (RS), has been proposed by Analyti and Pramanik in REF .
Reliable Semantics for Extended Logic Programs with Rule Prioritization
JOURNAL OF LOGIC AND COMPUTATION
Computer Science