We define a nonmonotonic formalism that shares some features with three other systems of nonmonotonic reasoning—default logic, logic programming with strong negation, and nonmonotonic causal logic—and study its possibilities as a language for describing actions. 1998 ACM Subject Classification D.1.6 Logic Programming

Uncertain information is present in many real applications e.g., medical domain, weather forecast, etc. The most common approaches for leading with this information are based on probability however some times; it is difficult to find suitable probabilities about some events. In this paper, we present a possibilistic logic programming approach which is based on possibilistic logic and PStable se...

Fuzzy Answer Set Programming (FASP) combines the nonmonotonic reasoning typical of Answer Set Programming with the capability of Fuzzy Logic to deal with imprecise information and paraconsistent reasoning. In the context of paraconsistent reasoning, the fundamental principle of minimal undefinedness states that truth degrees close to 0 and 1 should be preferred to those close to 0.5, to minimiz...

The foundations of a class of logic programming systems wi th the expressive power of full first-order logic and a non-monotonic component is addressed. The underlying refutation method is an extended version of weak model el imination. The first ques­ t ion addressed is how to compute answers with weak model el iminat ion when queries and programs are sets of arbitrary clauses, which is comple...

Defeasible logic is a simple but efficient rule-based non-monotonic logic. It has powerful implementations and shows promise to be applied in the areas of legal reasoning and the modelling of business rules. So far defeasible logic has been defined only proof-theoretically. Argumentation-based semantics have become popular in the area of logic programming. In this paper we give an argumentation...

We present a framework of logic programming using an explicit representation of defeats of assumptions, called assumption denials. We study semantics for extended, disjunctive, and extended disjunctive programs, all in the same framework. The framework is based on a x-point operator over \uninterpreted programs", and semantics for various kinds of programs are then deened simply by adding appro...

In other words whatever can be obtained from assumption A can still be obtained if we add to A more assumptions. In many cases, reasoning is non-monotonic. Consider the story below of the World-Trave-Agency (WTA). The story shall serve as the basis for introducing a system of non-monotonic logic. WTA offers package tours from New York to Paris and Stuttgart. Every Sunday, a group of New Yorkers...

In this paper we view nonmonotonic reasoning as a (special kind of) process. As temporal logic is a common formalism to specify and derive properties of processes, we introduce a variant of temporal logic as a general specification language for reasoning processes. We show that it is possible to execute finite specifications in this language, which leads to executability of a large class of fin...

Our purpose is to exhibit a modular systematic method of representing nonmonotonic reasoning problems with the Well Founded Semantics of extended logic programs aumented with eXplicit negation (WFSX), augmented by its Contradiction Removal Semantics (CRSX) when needed. We show how to cast in the language of such logic programs forms of non-monotonic reasoning like defeasible reasoning and hypot...

We propose a monotonic logic of internalised non-monotonic or instant interactive proofs (LiiP) and reconstruct an existing monotonic logic of internalised monotonic or persistent interactive proofs (LiP) as a minimal conservative extension of LiiP. Instant interactive proofs effect a fragile epistemic impact in their intended communities of peer reviewers that consists in the impermanent induc...