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Logic Programming and Knowledge Representation
 Journal of Logic Programming
, 1994
"... In this paper, we review recent work aimed at the application of declarative logic programming to knowledge representation in artificial intelligence. We consider exten sions of the language of definite logic programs by classical (strong) negation, disjunc tion, and some modal operators and sh ..."
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Cited by 242 (20 self)
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In this paper, we review recent work aimed at the application of declarative logic programming to knowledge representation in artificial intelligence. We consider exten sions of the language of definite logic programs by classical (strong) negation, disjunc tion, and some modal operators and show how each of the added features extends the representational power of the language.
Nonmonotonic Reasoning with Logic Programming
 LNAI
, 1993
"... Our purpose is to exhibit a modular systematic method of representing non monotonic reasoning problems with the Well Founded Semantics WFS of extended logic programs augmented with eXplicit negation (WFSX), augmented by its Contradiction Removal Semantics (CRSX) when needed. We apply this semantic ..."
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Cited by 41 (17 self)
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Our purpose is to exhibit a modular systematic method of representing non monotonic reasoning problems with the Well Founded Semantics WFS of extended logic programs augmented with eXplicit negation (WFSX), augmented by its Contradiction Removal Semantics (CRSX) when needed. We apply this semantics, and its contradiction removal semantics counterpart, to represent nonmonotonic reasoning problems. We show how to cast in the language of logic programs extended with explicit negation such forms of nonmonotonic reasoning as defeasible reasoning, abductive reasoning and hypothetical reasoning and apply them to such different domains of knowledge representation as hierarchies and reasoning about actions. We then abstract a modular systematic method of representing nonmonotonic problems in a logic programming semantics comprising two forms of negation avoiding some drawbacks of other proposals, with which we relate our work.
Representing Actions: Laws, Observations and Hypotheses
 Journal of Logic Programming
, 1997
"... We propose a modification L 1 of the action description language A. The language L 1 allows representation of hypothetical situations and hypothetical occurrence of actions (as in A) as well as representation of actual occurrences of actions and observations of the truth values of fluents in actual ..."
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Cited by 36 (3 self)
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We propose a modification L 1 of the action description language A. The language L 1 allows representation of hypothetical situations and hypothetical occurrence of actions (as in A) as well as representation of actual occurrences of actions and observations of the truth values of fluents in actual situations. The corresponding entailment relation formalizes various types of commonsense reasoning about actions and their effects not modeled by previous approaches. As an application of L 1 we also present an architecture for intelligent agents capable of observing, planning and acting in a changing environment based on the entailment relation of L 1 and use logic programming approximation of this entailment to implement a planning module for this architecture. We prove the soundness of our implementation and give a sucient condition for its completeness.
Prolegomena to Logic Programming for NonMonotonic Reasoning
"... The present prolegomena consist, as all indeed do, in a critical discussion serving to introduce and interpret the extended works that follow in this book. As a result, the book is not a mere collection of excellent papers in their own specialty, but provides also the basics of the motivation, b ..."
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Cited by 25 (16 self)
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The present prolegomena consist, as all indeed do, in a critical discussion serving to introduce and interpret the extended works that follow in this book. As a result, the book is not a mere collection of excellent papers in their own specialty, but provides also the basics of the motivation, background history, important themes, bridges to other areas, and a common technical platform of the principal formalisms and approaches, augmented with examples. In the
Scenario Semantics of Extended Logic Programs
, 1993
"... We present a coherent, flexible, unifying, and intuitive framework for the study of explicit negation in logic programs, based on the notion of admissible scenaria and the "coherence principle". With this support we introduce, in a simple way, a proposed "ideal sceptical semantics&quo ..."
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Cited by 17 (6 self)
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We present a coherent, flexible, unifying, and intuitive framework for the study of explicit negation in logic programs, based on the notion of admissible scenaria and the "coherence principle". With this support we introduce, in a simple way, a proposed "ideal sceptical semantics", as well as its well founded counterpart. Another result is a less sceptical "complete scenaria semantics", and its proof of equivalence to the wellfounded semantics with explicit negation (WFSX). This has the added benefict of bridging complete scenaria to default theory via WFSX, defined here based on GelfondLifschitz \Gamma operator.. Finally, we characterize a variety of more and less sceptical or credulous semantics, including answersets, and give sufficient conditions for equivalence between those semantics. Introduction In general, approaches to semantics follow two major intuitions: scepticism and credulity [30]. In logic programming, the credulous approach includes such semantics as stabl...
Contradiction Removal Semantics with Explicit Negation
 KNOWLEDGE REPRESENTATION AND REASONING UNDER UNCERTAINTY, NUMBER 808 IN LNAI
, 1992
"... Well Founded Semantics for logic programs extended with eXplicit negation (WFSX) is characterized by that, in any model, whenever :a (the explicit negation of a) holds, then ¸a (the negation by default of a) also holds. When explicit negation is used contradiction may be present (e.g. a and :a bot ..."
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Cited by 16 (12 self)
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Well Founded Semantics for logic programs extended with eXplicit negation (WFSX) is characterized by that, in any model, whenever :a (the explicit negation of a) holds, then ¸a (the negation by default of a) also holds. When explicit negation is used contradiction may be present (e.g. a and :a both hold for some a) and thus no semantics is given to the program. We introduce here the notion of removing some contradictions, through identifying the set of models obtained by revising closed world assumptions. One such unique model is singled out as the contradiction free semantics (CRSX). When contradiction does not arise, the contradiction removal semantics coincides with WFSX.
An Encompassing Framework for Paraconsistent Logic Programs
 J. Applied Logic
, 2003
"... We propose a framework which extends Antitonic Logic Programs [13] to an arbitrary complete bilattice of truthvalues, where belief and doubt are explicitly represented. Inspired by Ginsberg and Fitting 's bilattice approaches, this framework allows a precise de nition of important operato ..."
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Cited by 16 (6 self)
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We propose a framework which extends Antitonic Logic Programs [13] to an arbitrary complete bilattice of truthvalues, where belief and doubt are explicitly represented. Inspired by Ginsberg and Fitting 's bilattice approaches, this framework allows a precise de nition of important operators found in logic programming, such as explicit and default negation. In particular, it leads to a natural semantical integration of explicit and default negation through the Coherence Principle [38], according to which explicit negation entails default negation. We then de ne Coherent Answer Sets, and the Paraconsistent Wellfounded Model semantics, generalising many paraconsistent semantics for logic programs. In particular, Paraconsistent WellFounded Semantics with eXplicit negation (WFSXp ) [3, 11]. The framework is an extension of Antitonic Logic Programs for most cases, and is general enough to capture Probabilistic Deductive Databases, Possibilistic Logic Programming, Hybrid Probabilistic Logic Programs, and Fuzzy Logic Programming. Thus, we have a powerful mathematical formalism for dealing simultaneously with default, paraconsistency, and uncertainty reasoning. Results are provided about how our semantical framework deals with inconsistent information and with its propagation by the rules of the program.
Belief, provability and logic programs
 INTERNATIONAL WORKSHOP ON LOGICS IN ARTIFICIAL INTELLIGENCE, JELIA'94, VOLUME 838 OF LECTURE NOTES IN ARTIFICIAL INTELLIGENCE
, 1994
"... The main goal of this paper is to establish a nonmonotonic epistemic logic with two modalities – provability and belief – capable of expressing and comparing a variety of known semantics for extended logic programs, and clarify their meaning. In particular we present here, for the first time, embed ..."
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Cited by 3 (3 self)
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The main goal of this paper is to establish a nonmonotonic epistemic logic with two modalities – provability and belief – capable of expressing and comparing a variety of known semantics for extended logic programs, and clarify their meaning. In particular we present here, for the first time, embeddings into epistemic logic of logic programs extended with a second kind of negation under the well– founded semantics, and contrast them to the recent embeddings into autoepistemic logics of such programs under stable models based semantics. Because of the newly established relationship between our epistemic logic and extended program semantics, the former benefits from the procedures and implementations of the latter, and can be applied to at least the same class of AI problems that the latter can. Moreover, one issue of epistemic logic introduced here, belief revision, can profit from adapting techniques employed by the latter for contradiction removal. Furthermore, the language of the epistemic logic presented here being more general than that of extended programs, it offers a basic tool for further generalizations of the latter, for instance regarding disjunction and modal operators.
An Argumentation Theoretic Semantics Based on NonRefutable Falsity
"... Introduction In [PAA TCS] we've argued before that the WFS of normal programs is too sceptical, and then defined the more credulous Osemantics for normal programs. Take: arrested not free free not free free not arrested . In the WFM, argument not arrested is not acceptable because ..."
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Cited by 2 (1 self)
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Introduction In [PAA TCS] we've argued before that the WFS of normal programs is too sceptical, and then defined the more credulous Osemantics for normal programs. Take: arrested not free free not free free not arrested . In the WFM, argument not arrested is not acceptable because free} is evidence against it. So WFM = {}. . However free} is inconsistent, and should not count as evidence. . not arrested can be safely assumed: the only way to support arrested is inconsistent. The Osemantics is {free, not arrested}. Principles of Osemantics Any MOD(P ) can be added with a set A of negative literals (assumptions) if the following principles hold: . Consistent: MOD(P )#A #= L for not L A. . Sustainable: for not L A there is no consistent set A of assumptions defeating not L, i.e. such that MOD(P ) = . Maximal . Unique: There is consensus about a unique such set A. Introduction (cont.) We've defined WFSX [PA ECAI], extending WFS with