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Investigations Into a Theory of Knowledge Base Revision
, 1988
"... A fundamental problem in knowledge representation is how to revise knowledge when new, contradictory information is obtained. This paper formulates some desirable principles of knowledge revision, and investigates a new theory of knowledge revision that realizes these principles. This theory of revi ..."
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Cited by 240 (0 self)
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A fundamental problem in knowledge representation is how to revise knowledge when new, contradictory information is obtained. This paper formulates some desirable principles of knowledge revision, and investigates a new theory of knowledge revision that realizes these principles. This theory of revision can be explained at the knowledge level, in purely modeltheoretic terms. A syntactic characterization of the proposed approach is also presented. We illustrate its application through examples and compare it with several other approaches. 1 Introduction At the core of very many AI applications built in the past decade is a knowledge base  a system that maintains knowledge about the domain of interest. Knowledge bases need to be revised when new information is obtained. In many instances, this revision contradicts previous knowledge, so some previous beliefs must be abandoned in order to maintain consistency. As argued in [Ginsberg, 1986], such situations arise in diverse areas such...
On the Complexity of Propositional Knowledge Base Revision, Updates, and Counterfactuals
 ARTIFICIAL INTELLIGENCE
, 1992
"... We study the complexity of several recently proposed methods for updating or revising propositional knowledge bases. In particular, we derive complexity results for the following problem: given a knowledge base T , an update p, and a formula q, decide whether q is derivable from T p, the updated (or ..."
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Cited by 186 (12 self)
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We study the complexity of several recently proposed methods for updating or revising propositional knowledge bases. In particular, we derive complexity results for the following problem: given a knowledge base T , an update p, and a formula q, decide whether q is derivable from T p, the updated (or revised) knowledge base. This problem amounts to evaluating the counterfactual p > q over T . Besides the general case, also subcases are considered, in particular where T is a conjunction of Horn clauses, or where the size of p is bounded by a constant.
On the Logic of Merging
, 1998
"... This work proposes an axiomatic characterization of merging operators. It underlines the differences between arbitration operators and majority operators. A representation theorem is stated showing that each merging operator corresponds to a family of partial preorders on interpretations. Examples o ..."
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Cited by 112 (11 self)
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This work proposes an axiomatic characterization of merging operators. It underlines the differences between arbitration operators and majority operators. A representation theorem is stated showing that each merging operator corresponds to a family of partial preorders on interpretations. Examples of operators are given. They show the consistency of the axiomatic characterization. A new merging operator 4GMax is provided. It is proved that it is actually an arbitration operator. 1 Introduction In a growing number of applications, we face conflicting information coming from several sources. The problem is to reach a coherent piece of information from these contradicting ones. A lot of different merging methods have already been given [BI84, LMa, BKM91, BKMS92, Sub94]. Instead of giving one particular merging method we propose, in this paper, a characterization of such methods following the rationality of the postulates they satisfy. We shall call merging operators those meth...
Updates and Counterfactuals
 In: Proceedings of the Second International Conference on Principles of Knowledge Representation and Reasoning
, 1991
"... We study the problem of combining updates a special instance of theory change and counterfactual conditionals in propositional knowledgebases. Intuitively, an update means that the world described by the knowledgebase has changed. This is opposed to revisions another instance of theory chan ..."
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Cited by 47 (3 self)
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We study the problem of combining updates a special instance of theory change and counterfactual conditionals in propositional knowledgebases. Intuitively, an update means that the world described by the knowledgebase has changed. This is opposed to revisions another instance of theory change where our knowledge about a static world changes. A counterfactual implication is a statement of the form `If A were the case, then B would also be the case', where the negation of A may be derivable from our current knowledge. We present a decidable logic, called VCU 2 , that has both update and counterfactual implication as connectives in the object language. Our update operator is a generalization of operators previously proposed and studied in the literature. We show that our operator satisfies certain postulates set forth for any reasonable update. The logic VCU 2 is an extension of D. K. Lewis' logic VCU for counterfactual conditionals. The semantics of VCU 2 is that of a m...
Merging with Integrity Constraints
, 1999
"... We consider, in this paper, the problem of knowledge base merging with integrity constraints. We propose a logical characterization of those operators and give a representation theorem in terms of preorders on interpretations. We show the close connection between belief revision and merging oper ..."
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Cited by 45 (10 self)
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We consider, in this paper, the problem of knowledge base merging with integrity constraints. We propose a logical characterization of those operators and give a representation theorem in terms of preorders on interpretations. We show the close connection between belief revision and merging operators and we show that our proposal extends the pure merging case (i.e. without integrity constraints) we study in a previous work. Finally we show that Liberatore and Schaerf commutative revision operators can be seen as a special case of merging.
Syntactic Characterizations of Belief Change Operators
 In Proc. of IJCAI'93, the Thirteenth International Joint Conference on Artificial Intelligence
, 1993
"... We provide syntactic characterizations for a number of propositional modelbased belief revision and update operators proposed in the literature, as well as algorithms based on these characterizations. 1 Introduction In this paper, we provide syntactic characterizations and algorithms for a number ..."
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Cited by 13 (3 self)
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We provide syntactic characterizations for a number of propositional modelbased belief revision and update operators proposed in the literature, as well as algorithms based on these characterizations. 1 Introduction In this paper, we provide syntactic characterizations and algorithms for a number of belief change operators proposed in the literature. We already characterized Winslett's `possible models approach' (PMA) update operators in [ del Val, 1992b ] , where we explored in depth some of the operators in the PMA family, provided algorithms to compute them and experimentally showed that they could be of practical value for (small) updates of quite large databases. In this paper, we show how other operators can be characterized in a very similar way, and show how to design algorithms for computing the result of applying these operators to disjunctive, negation and conjunctive normal form (DNF, NNF and CNF, respectively) databases, which return a database in the same format. The i...
Ontology evolution: A framework and its application to RDF
 Proceedings of the Joint ODBIS & SWDB Workshop on Semantic Web, Ontologies, Databases
"... The algorithms dealing with the incorporation of new knowledge in an ontology often share a rather standard process of dealing with changes. This process consists of the determination of the allowed change operations, the identification of the inconsistencies that could be caused by each such operat ..."
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Cited by 6 (2 self)
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The algorithms dealing with the incorporation of new knowledge in an ontology often share a rather standard process of dealing with changes. This process consists of the determination of the allowed change operations, the identification of the inconsistencies that could be caused by each such operation as well as the various alternatives to deal with each such inconsistency, and, finally, some (manual or automatic) selection mechanism that allows the determination of the “best ” of these alternatives. Unfortunately, most ontology evolution algorithms implement these steps using a casebased, adhoc methodology, which is cumbersome and errorprone. In this paper we propose a general framework for ontology change management that generalizes the methodology employed by existing tools. The introduction of this framework allows us to devise a whole class of ontology evolution algorithms, which, due to their formal underpinnings, avoid many of the problems exhibited by adhoc frameworks. We exploit this framework by implementing a specific ontology evolution algorithm for RDF ontologies. 1.
Revision by Translation
, 1999
"... In this paper, we show that it is possible to accomplish belief revision in any logic which is translatable to classical logic. We give the example of the propositional modal logic K and show that a belief operation in K defined in terms of K # s translation to classical logic verifies the AGM postu ..."
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Cited by 4 (0 self)
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In this paper, we show that it is possible to accomplish belief revision in any logic which is translatable to classical logic. We give the example of the propositional modal logic K and show that a belief operation in K defined in terms of K # s translation to classical logic verifies the AGM postulates. Contents 1 Introduction 2 2 Belief Revision 3 3 Revising in the modal logic K 8 4 Conclusions 11 5 Acknowledgments 12 1 1 Introduction This paper will present a method for revision of theories in logics other than classical logic. The idea is to translate the other logic into firstorder classical logic, perform the revision there and then translate back. The general schema looks as follows. Let # a be a revision process in classical logic. Typically, given a classical logic theory # an input formula # 1 , the operation # a gives us a new theory # = ## a #, corresponding to the result of the revision of # by #. Ideally, # a has some desirable properties, for instance, the...
Collective decisionmaking without paradoxes: A fusion approach
, 2005
"... The combination of individual judgments on logically interconnected propositions into a collective decision on the same propositions is called judgment aggregation. Literature in social choice and political theory has claimed that judgment aggregation raises serious concerns. For example, consider a ..."
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Cited by 3 (1 self)
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The combination of individual judgments on logically interconnected propositions into a collective decision on the same propositions is called judgment aggregation. Literature in social choice and political theory has claimed that judgment aggregation raises serious concerns. For example, consider a set of premises and a conclusion in which the latter is logically equivalent to the former. When majority voting is applied to some propositions (the premises) it may give a different outcome than majority voting applied to another set of propositions (the conclusion). This problem is known as the doctrinal paradox. The doctrinal paradox is a serious problem since it is not clear whether a collective outcome exists in these cases, and if it does, what it is like. Moreover, the two suggested escaperoutes from the paradox the socalled premisebased procedure and the conclusionbased procedure are not, as I will show, satisfactory methods for group decisionmaking. In this paper I introduce a new aggregation procedure inspired by an operator defined in artificial intelligence in order to merge knowledge bases. The result is that we do not need to worry about paradoxical outcomes, since these arise only when inconsistent collective judgments are not ruled out from the set of possible solutions.