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29
Dynamic Updates of NonMonotonic Knowledge Bases
, 2000
"... In this paper we investigate updates of knowledge bases represented by logic programs. In order to represent negative information, we use generalized logic programs which allow default negation not only in rule bodies but also in their heads.We start by introducing the notion of an update P \Phi U o ..."
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Cited by 150 (82 self)
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In this paper we investigate updates of knowledge bases represented by logic programs. In order to represent negative information, we use generalized logic programs which allow default negation not only in rule bodies but also in their heads.We start by introducing the notion of an update P \Phi U of one logic program P by another logic program U . Subsequently, we provide a precise semantic characterization of P \Phi U , and study some basic properties of program updates. In particular, we show that our update programs generalize the notion of interpretation update. We then extend this notion to compositional sequences of logic programs updates P1 \Phi P2 \Phi : : : , defining a dynamic program update, and thereby introducing the paradigm of dynamic logic programming. This paradigm significantly facilitates modularization of logic programming, and thus modularization of nonmonotonic reasoning as a whole. Specifically, suppose that we are given a set of logic program modules, each de...
Dynamic Logic Programming
 LINKÖPING ELECTRONIC ARTICLES IN COMPUTER AND INFORMATION SCIENCE
, 1997
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LUPS  a language for updating logic programs
, 2000
"... Most of the work conducted so far in the eld of logic programming has focused on representing static knowledge, i.e. knowledge that does not evolve with time. To overcome this limitation, in a recent paper, the authors introduced dynamic logic programming. There, they studied and dened the declarati ..."
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Cited by 75 (36 self)
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Most of the work conducted so far in the eld of logic programming has focused on representing static knowledge, i.e. knowledge that does not evolve with time. To overcome this limitation, in a recent paper, the authors introduced dynamic logic programming. There, they studied and dened the declarative and operational semantics of sequences of logic programs (or dynamic logic programs). Each program in the sequence contains knowledge about some given state, where dierent states may, for example, represent dierent time periods or dierent sets of priorities. But how, in concrete situations, is a sequence of logic programs built? For instance, in the domain of actions, what are the appropriate sequences of programs that represent the performed actions and their eects? Whereas dynamic logic programming provides a way for, given the sequence, determining what should follow, it does not provide a good practical language for the specication of the sequence of updates which may be condi...
Generalizing Updates: from Models to Programs
, 1997
"... Recently the field of theory update has seen some improvement, in what concerns model updating, by allowing updates to be specified by socalled revision programs. The updating of theory models is governed by their update rules and also by inertia applied to those literals not directly affected by t ..."
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Cited by 61 (36 self)
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Recently the field of theory update has seen some improvement, in what concerns model updating, by allowing updates to be specified by socalled revision programs. The updating of theory models is governed by their update rules and also by inertia applied to those literals not directly affected by the update program. Though this is important, it remains necessary to tackle as well the updating of programs specifying theories. Some results have been obtained on the issue of updating a logic program which encodes a set of models, to obtain a new program whose models are the desired updates of the initial models. But here the program only plays the rôle of a means to encode the models. A logic program encodes much more than a set of models: it encodes knowledge in the form of the relationships between the elements of those models. In this paper we advocate that the principle of inertia is advantageously applied to the rules of the initial program rather than to the individual literals in...
Logic Program Updates
, 1997
"... The field of theory update has seen some major improvements in what concerns model updating. The update of models is governed by update rules and by inertia applied to the literals not directly aoeected by the update program. This is important but it is still necessary to tackle as well the updating ..."
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Cited by 28 (12 self)
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The field of theory update has seen some major improvements in what concerns model updating. The update of models is governed by update rules and by inertia applied to the literals not directly aoeected by the update program. This is important but it is still necessary to tackle as well the updating of programs. Some results have been obtained on the issue of updating a logic program which encodes a set of models, to obtain a new program whose models are the desired updates of the initial models. But here the program only plays the rôle of a means to encode the models. A logic program encodes much more than a set of models: it encodes the relationships between the elements of those models. In this dissertation we advocate that the principle of inertia is advantageously applied to the rules of the initial program rather than to the individual literals in a model. Indeed, we show how this concept of program update generalizes simple interpretation update. We will consider both the 2valued...
A Kripkean Semantics for Dynamic Logic Programming
, 2000
"... The main goal of the paper is to propose a tool for a semantic specication of program updates (in the context of dynamic logic programming paradigm). A notion of Kripke structure KP associated with a generalized logic program P is introduced. It is shown that some paths in KP specify stable mode ..."
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Cited by 12 (5 self)
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The main goal of the paper is to propose a tool for a semantic specication of program updates (in the context of dynamic logic programming paradigm). A notion of Kripke structure KP associated with a generalized logic program P is introduced. It is shown that some paths in KP specify stable models of P and vice versa, to each stable model of P corresponds a path in KP . An operation on Kripke structures is de ned: for Kripke structures KP and KU associated with P (the original program) and U (the updating program), respectively, a Kripke structure KPU is constructed. KPU species (in a reasonable sense) a set of updates of P by U . There is a variety of possibilities for a selection of an updated program. 1
The Rise and Fall of Semantic Rule Updates Based on SEModels
 UNDER CONSIDERATION FOR PUBLICATION IN THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2013
"... Logic programs under the stable model semantics, or answerset programs, provide an expressive rulebased knowledge representation framework, featuring a formal, declarative and wellunderstood semantics. However, handling the evolution of rule bases is still a largely open problem. The AGM framewor ..."
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Cited by 12 (3 self)
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Logic programs under the stable model semantics, or answerset programs, provide an expressive rulebased knowledge representation framework, featuring a formal, declarative and wellunderstood semantics. However, handling the evolution of rule bases is still a largely open problem. The AGM framework for belief change was shown to give inappropriate results when directly applied to logic programs under a nonmonotonic semantics such as the stable models. The approaches to address this issue, developed so far, proposed update semantics based on manipulating the syntactic structure of programs and rules. More recently, AGM revision has been successfully applied to a significantly more expressive semantic characterisation of logic programs based on SEmodels. This is an important step, as it changes the focus from the evolution of a syntactic representation of a rule base to the evolution of its semantic content. In this paper, we borrow results from the area of belief update to tackle the problem of updating (instead of revising) answerset programs. We prove a representation theorem which makes it possible to constructively define any operator satisfying a set of postulates derived from Katsuno and Mendelzon’s postulates for belief update. We define a specific operator based on this theorem, examine its computational complexity and compare the behaviour of this operator with syntactic rule update semantics from the literature. Perhaps surprisingly, we uncover a serious drawback of all rule update operators based on Katsuno and Mendelzon’s approach to update and on SEmodels.
Program Updating by Incremental and Answer Subsumption Tabling
"... Abstract. We explore the use of stateoftheart Logic Programming (LP) implementation techniques to exploit their use in addressing a classical nonmonotonic reasoning problem, that of LP program updates, with incidence on representing change, i.e. internal or self and external or world changes. We ..."
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Cited by 7 (7 self)
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Abstract. We explore the use of stateoftheart Logic Programming (LP) implementation techniques to exploit their use in addressing a classical nonmonotonic reasoning problem, that of LP program updates, with incidence on representing change, i.e. internal or self and external or world changes. We do so starting from a given LP update language and a given LP implementation system. We propose and foster a novel conceptual approach to program updates implementation that especially exploits two recent features of tabling in logic programming (in XSB Prolog): incremental and answer subsumption tabling. Our approach, termed EVOLP/R, is based on and follows the paradigm and constructs of Evolving Logic Programs (EVOLP), but simplifies it at first by restricting updates to fluents only. Rule updates are nevertheless achieved via the mechanism of rule name fluents, placed in rules ’ bodies, permitting to turn rules on or off, through assertions or retractions of their corresponding unique name fluents. Incremental tabling of fluents allows to automatically maintain – at engine level – the consistency of program states, analogously to an assumption based truthmaintenance
Monotone expansions of updates in logical databases
 In: Proc. of 5th International Conference LPNMR’99. LNAI 1730
, 1999
"... Abstract. To find a minimal real change after an update of a database with integrity constraints (IC) expressed by an extended logic program is proven to be a Σp2complete problem. We define a class of operators expanding the input updates correctly with respect to the IC. The particular monotone e ..."
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Cited by 6 (2 self)
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Abstract. To find a minimal real change after an update of a database with integrity constraints (IC) expressed by an extended logic program is proven to be a Σp2complete problem. We define a class of operators expanding the input updates correctly with respect to the IC. The particular monotone expansion operator we describe is incrementally computed in square time. It provides a practical optimization of the standard complete choice algorithm resolving the update problem. 1