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Classical Negation in Logic Programs and Disjunctive Databases
 New Generation Computing
, 1991
"... An important limitation of traditional logic programming as a knowledge representation tool, in comparison with classical logic, is that logic programming does not allow us to deal directly with incomplete information. In order to overcome this limitation, we extend the class of general logic progra ..."
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Cited by 846 (74 self)
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An important limitation of traditional logic programming as a knowledge representation tool, in comparison with classical logic, is that logic programming does not allow us to deal directly with incomplete information. In order to overcome this limitation, we extend the class of general logic programs by including classical negation, in addition to negationasfailure. The semantics of such extended programs is based on the method of stable models. The concept of a disjunctive database can be extended in a similar way. We show that some facts of commonsense knowledge can be represented by logic programs and disjunctive databases more easily when classical negation is available. Computationally, classical negation can be eliminated from extended programs by a simple preprocessor. Extended programs are identical to a special case of default theories in the sense of Reiter. 1 Introduction An important limitation of traditional logic programming as a knowledge representation tool, in comp...
Propositional Semantics for Disjunctive Logic Programs
 Annals of Mathematics and Artificial Intelligence
, 1994
"... In this paper we study the properties of the class of headcyclefree extended disjunctive logic programs (HEDLPs), which includes, as a special case, all nondisjunctive extended logic programs. We show that any propositional HEDLP can be mapped in polynomial time into a propositional theory such th ..."
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Cited by 145 (2 self)
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In this paper we study the properties of the class of headcyclefree extended disjunctive logic programs (HEDLPs), which includes, as a special case, all nondisjunctive extended logic programs. We show that any propositional HEDLP can be mapped in polynomial time into a propositional theory such that each model of the latter corresponds to an answer set, as defined by stable model semantics, of the former. Using this mapping, we show that many queries over HEDLPs can be determined by solving propositional satisfiability problems. Our mapping has several important implications: It establishes the NPcompleteness of this class of disjunctive logic programs; it allows existing algorithms and tractable subsets for the satisfiability problem to be used in logic programming; it facilitates evaluation of the expressive power of disjunctive logic programs; and it leads to the discovery of useful similarities between stable model semantics and Clark's predicate completion. 1 Introduction ...
Logic and Databases: a 20 Year Retrospective
, 1996
"... . At a workshop held in Toulouse, France in 1977, Gallaire, Minker and Nicolas stated that logic and databases was a field in its own right (see [131]). This was the first time that this designation was made. The impetus for this started approximately twenty years ago in 1976 when I visited Gallaire ..."
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Cited by 53 (1 self)
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. At a workshop held in Toulouse, France in 1977, Gallaire, Minker and Nicolas stated that logic and databases was a field in its own right (see [131]). This was the first time that this designation was made. The impetus for this started approximately twenty years ago in 1976 when I visited Gallaire and Nicolas in Toulouse, France, which culminated in a workshop held in Toulouse, France in 1977. It is appropriate, then to provide an assessment as to what has been achieved in the twenty years since the field started as a distinct discipline. In this retrospective I shall review developments that have taken place in the field, assess the contributions that have been made, consider the status of implementations of deductive databases and discuss the future of work in this area. 1 Introduction As described in [234], the use of logic and deduction in databases started in the late 1960s. Prominent among the developments was the work by Levien and Maron [202, 203, 199, 200, 201] and Kuhns [1...
Formalizing a logic for logic programming
 Annals of Mathematics and Artificial Intelligence
, 1992
"... ..."
On the impact of stratification on the complexity of nonmonotonic reasoning
 PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON PRINCIPLES OF KNOWLEDGE REPRESENTATION AND REASONING
, 1992
"... This paper investigates the problem of finding subclasses of nonmonotonic reasoning which can be implemented efficiently. The ability to "define" propositions using default assumptions about the same propositions is identified as a major source of computational complexity in nonmonotonic reasoning ..."
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Cited by 16 (4 self)
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This paper investigates the problem of finding subclasses of nonmonotonic reasoning which can be implemented efficiently. The ability to "define" propositions using default assumptions about the same propositions is identified as a major source of computational complexity in nonmonotonic reasoning. If such constructs are not allowed, i.e. stratied knowledge bases are considered, a significant computational advantage is obtained. This is demonstrated by developing an iterative algorithm for propositional stratified autoepistemic theories the complexity of which is dominated by required classical reasoning. Thus efficient subclasses of stratied nonmonotonic reasoning can be obtained by further restricting the form of sentences in a knowledge base. As an example quadratic and linear time algorithms for specific subclasses of stratified autoepistemic theories are derived. The results are shown to imply efficient reasoning methods for stratied cases of default logic, logic programs, truth maintenance systems, and nonmonotonic modal logics.
CONTEXTSENSITIVE POINTER ANALYSIS USING BINARY DECISION DIAGRAMS
, 2007
"... in my opinion, it ..."
Semantics for Disjunctive Logic Programs with Explicit and Default Negation
 Fundamenta Informaticae
, 1994
"... The use of explicit negation enhances the expressive power of logic programs by providing a natural and unambiguous way to assert negated information about the domain being represented. We study the semantics of disjunctive programs that contain both explicit negation and negationby default, called ..."
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Cited by 12 (2 self)
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The use of explicit negation enhances the expressive power of logic programs by providing a natural and unambiguous way to assert negated information about the domain being represented. We study the semantics of disjunctive programs that contain both explicit negation and negationby default, called extended disjunctive logic programs. General techniques are described for extending model, fixpoint, and proof theoretic characterizations of an arbitrary semantics of normal disjunctive logic programs to cover the class of extended programs. Illustrations of these techniques are given for stable models, disjunctive wellfounded and stationary semantics. The declarative complexity of the extended programs, as well as the algorithmic complexity of the proof procedures and fixpoint operators, are discussed. 1 Introduction The purpose of this paper is to study, in a comprehensive manner, different aspects of extended disjunctive logic programs (edlps for short), that is, programs whose clause...
Logic and artificial intelligence
 The Stanford Encyclopedia of Philosophy. Fall 2003. http://plato.stanford.edu/archives/fall2003/entries/logicai
"... www.rthomaso.eecs.umich.edu ..."
Stable Classes and Operator Pairs for Disjunctive Programs
 Proc. of the 3rd Int. Conference on Logic Programming and Nonmonotonic Reasoning
, 1995
"... . Baral and Subrahmanian introduced the notion of stable classes for normal logic programs. In contrast to stable models stable classes always exist and can be given a constructive characterization. We generalize the BaralSubrahmanian approach to disjunctive programs and propose mf stable classes ..."
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Cited by 2 (2 self)
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. Baral and Subrahmanian introduced the notion of stable classes for normal logic programs. In contrast to stable models stable classes always exist and can be given a constructive characterization. We generalize the BaralSubrahmanian approach to disjunctive programs and propose mf stable classes for different functions mf . Such mf stable classes always exist and are sound with respect to stable model semantics. Operationalizations for approximate but efficient query evaluation are defined in terms of threevalued interpretations and their relation with mf stable classes is analyzed. Finally, analogous concepts are given for an approach based on states instead of models. 1 Introduction Stable model semantics as proposed by Gelfond and Lifschitz [5] is one of the most elegant approaches concerning the semantics of normal logic programs. It generalizes the perfect model semantics and is closely related with Autoepistemic Logic [14] as a major formalization of nonmonotonic reasoning...