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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 55 (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...
Knowledge Representation with Logic Programs
 DEPT. OF CS OF THE UNIVERSITY OF KOBLENZLANDAU
, 1996
"... In this tutorialoverview, which resulted from a lecture course given by the authors at ..."
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Cited by 31 (6 self)
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In this tutorialoverview, which resulted from a lecture course given by the authors at
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 22 (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
DisLoP: A Research Project on Disjunctive Logic Programming
 AI COMMUNICATIONS
, 1997
"... This paper gives a brief highlevel description of what has been done in the Disjunctive Logic Programmingproject (funded by Deutsche ForschungsGemeinschaft), undertaken by the University of Koblenz since July 1995. We present the main ideas, cite the relevant papers and point to the implemented s ..."
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Cited by 19 (4 self)
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This paper gives a brief highlevel description of what has been done in the Disjunctive Logic Programmingproject (funded by Deutsche ForschungsGemeinschaft), undertaken by the University of Koblenz since July 1995. We present the main ideas, cite the relevant papers and point to the implemented systems and how to access them. This paper also serves as a brief survey of the current status of disjunctive logic programming by highlighting important developments and providing enough pointers for further reading.
Improving the Alternating Fixpoint: The Transformation Approach
, 1997
"... . We present a bottomup algorithm for the computation of the wellfounded model of nondisjunctive logic programs which is based on the set of elementary program transformations studied by Brass and Dix [4, 5]. The transformation approach has been introduced in more detail in [7]. In this paper we ..."
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Cited by 9 (0 self)
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. We present a bottomup algorithm for the computation of the wellfounded model of nondisjunctive logic programs which is based on the set of elementary program transformations studied by Brass and Dix [4, 5]. The transformation approach has been introduced in more detail in [7]. In this paper we present a deeper analysis of its complexity and describe an optimized SCCoriented evaluation. We show that by our method no more work is done than by the alternating fixpoint procedure [23, 24] and that there are examples where our algorithm is significantly superior. 1 Introduction It is likely that the next generation of deductive database systems will support the full class of normal programs and that the wellfounded semantics will be chosen by nearly all system designers, because it has a unique model. Whereas the SLGresolution of Chen and Warren [10, 11, 12] is an elaborate topdown method for the computation of the wellfounded model of a normal program that already led to a full...
A Comparison of the Static and the Disjunctive Wellfounded Semantics
, 1998
"... . In recent years, much work was devoted to the study of theoretical foundations of Disjunctive Logic Programs and Disjunctive Deductive Databases. While the semantics of nondisjunctive programs is fairly well understood the declarative and computational foundations of disjunctive programming prov ..."
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Cited by 7 (1 self)
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. In recent years, much work was devoted to the study of theoretical foundations of Disjunctive Logic Programs and Disjunctive Deductive Databases. While the semantics of nondisjunctive programs is fairly well understood the declarative and computational foundations of disjunctive programming proved to be much more elusive and difficult. Quite recently, two new and very promising semantics have been proposed for the class of disjunctive logic programs. Both of them extend the wellfounded semantics of normal programs. The first one is the static semantics proposed by Przymusinski and the other is the DWFS semantics proposed by Brass and Dix. Although the two semantics are based on very different ideas, we show in this paper that they turn out to be very closely related. In fact, we show that it is possible to restrict the underlying language of STATIC to get DWFS. We also show how to use this characterization for an efficient implementation based on a prover for computing minimal ...
Computation of NonGround Disjunctive WellFounded Semantics with Constraint Logic Programming
 Nonmonotonic Extensions of Logic Programming, LNAI 1216
, 1997
"... . Impressive work has been done in the last years concerning the meaning of negation and disjunction in logic programs, but most of this research concentrated on propositional programs only. While it suffices to consider the propositional case for investigating general properties and the overall ..."
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Cited by 7 (3 self)
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. Impressive work has been done in the last years concerning the meaning of negation and disjunction in logic programs, but most of this research concentrated on propositional programs only. While it suffices to consider the propositional case for investigating general properties and the overall behaviour of a semantics, we feel that for real applications and for computational purposes an implementation should be able to handle firstorder programs without grounding them. In this paper we present a theoretical framework by defining a calculus of program transformations that apply directly to rules with variables and function symbols. Our main results are that (1) this calculus is confluent for arbitrary programs, (2) for finite ground programs it is equivalent to a terminating calculus introduced by Brass and Dix (1995), and (3) it approximates a generalisation of DWFS for arbitrary programs. We achieve this by transforming program rules into rules with equational constr...
Back and Forth Semantics for Normal, Disjunctive and Extended Logic Programs
 In Proceedings of the Joint Conference on Declarative Programming (APPIAGULPPRODE'98
, 1998
"... We define a logical semantics called backandforth, applicable to normal and disjunctive datalog programs as well as to programs possessing a second, explicit or `strong' negation operator. We show that on normal programs it is equivalent to the wellfounded semantics (WFS), and that on disjunctive ..."
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We define a logical semantics called backandforth, applicable to normal and disjunctive datalog programs as well as to programs possessing a second, explicit or `strong' negation operator. We show that on normal programs it is equivalent to the wellfounded semantics (WFS), and that on disjunctive programs it is equivalent to the Pstable semantics of Eiter, Leone and Sacc`a, hence to Przymusinski's 3valued stable semantics. The main advantage is that it is characterised by simple conditions on models in a wellknown nonclassical logic and therefore provides a better insight into the nature of partial stable models from a logical standpoint. It also suggests why the Pstable models are a natural generalisation of WFS to the disjunctive case. On extended programs with strong negation, the backandforth semantics is apparently new, differing from answer sets, from WSFX and from the static semantics. Keywords: stable models, Pstable models, disjunctive programs, intermediate logics,...
Comparison and Efficient Computation of the STATIC and the Disjunctive Wellfounded Semantics
, 1997
"... While the semantics of nondisjunctive programs is now fairly well understood, the declarative and computational foundations of disjunctive programming proved to be much more elusive and difficult. Quite recently, two new and very promising semantics have been introduced for the class of disjunctive ..."
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Cited by 1 (0 self)
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While the semantics of nondisjunctive programs is now fairly well understood, the declarative and computational foundations of disjunctive programming proved to be much more elusive and difficult. Quite recently, two new and very promising semantics have been introduced for the class of disjunctive logic programs: STATIC proposed by Przymusinski and DWFS proposed by Brass and Dix. Although the two semantics are based on very different ideas, we show in this paper that they turn out to be very closely related. We also show how to use our characterizations for an efficient implementation based on a prover for computing minimal models for positive disjunctive programs. Contrary to most other implementations of (disjunctive) semantics, ours works in polynomial space. 1 Introduction In natural discourse as well as in various programming applications we often use disjunctive statements. That is why considerable interest and research effort has been recently devoted to disjunctive logic p...
A Comparison of STATIC Semantics with DWFS
, 1996
"... In recent years, much work was devoted to the study of theoretical foundations of Disjunctive Logic Programs and Disjunctive Deductive Databases . While the semantics of nondisjunctive programs is fairly well understood the declarative and computational foundations of disjunctive programming pro ..."
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In recent years, much work was devoted to the study of theoretical foundations of Disjunctive Logic Programs and Disjunctive Deductive Databases . While the semantics of nondisjunctive programs is fairly well understood the declarative and computational foundations of disjunctive programming proved to be much more elusive and difficult. Quite recently, two new and very promising semantics have been proposed for the class of disjunctive logic programs. Both of them extend the wellfounded semantics of normal programs. The first one is the static semantics proposed by Przymusinski and the other is the DWFS semantics proposed by Brass and Dix. Although the two semantics are based on very different ideas, we show in this paper that they turn out to be very closely related. In fact, we show that (i) it is possible to restrict the underlying language of STATIC to get DWFS, and (ii) it is possible to define a simple transformation P 7! P cp such that DWFS(P cp ) = STATIC(P ...