共查询到20条相似文献,搜索用时 15 毫秒
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本文在相信逻辑中引入相信解释与相信模的概念,从语义上把相信逻辑改造成非单调逻辑。一个缺省理论可以直接转换成一个相信逻辑理论,本文中证明了一个缺省理论外延的模集就是对应相信理论的模,从而为缺省理论提供了一种简便的语义。 相似文献
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利用格论研究缺省推理 总被引:1,自引:1,他引:0
本文提出了一组转换规则,使用这组转换规则可以把缺省规则转换成扩展规则,然后使用这些扩展规则去扩展缺省理论的初始逻辑公式集合,在这些扩展规则的基础上,我们提出了缺省格(default lattice)的概念,证明了缺省理论的外延刚好对应于它的缺省格的相容性集合的D-极大值,因此可以使用缺省格求出缺省理论的所有外延. 相似文献
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本文在布尔环重量写系统中研究了缺省逻辑。一个缺省理论等价于一个布尔环方程组。本文还分析了命题缺省理论外延的结构,证明了一个缺省理论的外延的模型集合就是对应的布尔环方程组的极大缺省解,从而为确定缺省理论的外延提供了一种简便实用的方法。 相似文献
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When reasoning about complex domains, where information available is usually only partial, nonmonotonic reasoning can be an important tool. One of the formalisms introduced in this area is Reiter's Default Logic (1980). A characteristic of this formalism is that the applicability of default (inference) rules can only be verified in the future of the reasoning process. We describe an interpretation of default logic in temporal epistemic logic which makes this characteristic explicit. It is shown that this interpretation yields a semantics for default logic based on temporal epistemic models. A comparison between the various semantics for default logic will show the differences and similarities of these approaches and ours. 相似文献
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Abstract argumentation systems 总被引:9,自引:0,他引:9
《Artificial Intelligence》1997,90(1-2):225-279
In this paper, we develop a theory of abstract argumentation systems. An abstract argumentation system is a collection of “defeasible proofs”, called arguments, that is partially ordered by a relation expressing the difference in conclusive force. The prefix “abstract” indicates that the theory is concerned neither with a specification of the underlying language, nor with the development of a subtheory that explains the partial order. An unstructured language, without logical connectives such as negation, makes arguments not (pairwise) inconsistent, but (groupwise) incompatible. Incompatibility and difference in conclusive force cause defeat among arguments. The aim of the theory is to find out which arguments eventually emerge undefeated. These arguments are considered to be in force. Several results are established. The main result is that arguments that are in force are precisely those that are in the limit of a so-called complete argumentation sequence. 相似文献
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非单调推理的研究现状 总被引:1,自引:0,他引:1
一、引言 早在1959年,McCart~[1]就发现常识和常识推理很难处理,因为在常识推理中当前得出的结论,可能会由于以后新事实的加入而被取消.这就是所谓的“非单调性”。 相似文献
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James P. Delgrande 《Annals of Mathematics and Artificial Intelligence》2006,48(3-4):135-167
In nonmonotonic reasoning, a default conditional α→β has most often been informally interpreted as a defeasible version of a classical conditional, usually the material conditional.
There is however an alternative interpretation, in which a default is regarded essentially as a rule, leading from premises
to conclusion. In this paper, we present a family of logics, based on this alternative interpretation. A general semantic
framework under this rule-based interpretation is developed, and associated proof theories for a family of weak conditional
logics is specified. Nonmonotonic inference is easily defined in these logics. Interestingly, the logics presented here are
weaker than the commonly-accepted base conditional approach for defeasible reasoning. However, this approach resolves problems
that have been associated with previous approaches.
相似文献
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缺省推理是各种非单调推理系统中最在影响的系统之一。R。Reiter对规范缺省理论作了一系列的研究。他还提出了证明理论,并证明了这一证明理论对于规范缺省理论来说是完备的。W。Etherington则提出了应用范围更为广泛的有序半规范缺省理论。本文先证明了这类缺省理论具有半单调性等各种性质,然后证明了R。Reiter的证明理论对于有序半规范缺省理论也是完备的。 相似文献
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Refinement of logical theories plays an important role in various application domains, notably in software engineering. This
note introduces and studies refinement notions for nonmonotonic knowledge bases in default logic. The paper motivates and
proposes refinement concepts, discusses their relationship, and establishes sufficient conditions for refinement.
Received 27 July 1999 / Revised 3 November 1999 / Accepted 24 May 2000 相似文献
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Rachel Ben-Eliyahu-Zohary 《Artificial Intelligence》2002,139(1):1-20
We identify several new tractable subsets and several new intractable simple cases for reasoning in the propositional version of Reiter's default logic. The majority of our findings are related to brave reasoning. By making some intuitive observations, most classes that we identify can be derived quite easily from some subsets of default logic already known in the literature. Some of the subsets we discuss are subclasses of the so-called “extended logic programs”. All the tractable subsets presented in this paper can be recognized in linear time. 相似文献
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Reasoning almost always occurs in the face of incomplete information. Such reasoning is nonmonotonic in the sense that conclusions drawn may later be withdrawn when additional information is obtained. There is an active literature on the problem of modeling such nonmonotonic reasoning, yet no category of method-let alone a single method-has been broadly accepted as the right approach. This paper introduces a new method, called sweeping presumptions, for modeling nonmonotonic reasoning. The main goal of the paper is to provide an example-driven, nontechnical introduction to the method of sweeping presumptions, and thereby to make it plausible that sweeping presumptions can usefully be applied to the problems of nonmonotonic reasoning. The paper discusses a representative sample of examples that have appeared in the literature on nonmonotonic reasoning, and discusses them from the point of view of sweeping presumptions. 相似文献
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As an important variant of Reiter‘s default logic.Poole(1988) developed a nonmonotonic reasoning framework in the classical first-order language,Brewka and Nebel extended Poole‘s approach in order to enable a representation of priorities between defaults.In this paper a general framework for default reasoning is presented,which can be viewed as a generalization of the three approaches above.It is proved that the syntax-independent default reasoning in this framework is identical to the general belief revision operation introduced by Zhang et al.(1997).This esult provides a solution to the problem whether there is a correspondence between belief revision and default logic for the infinite case .As a by-product,an answer to the the question,raised by Mankinson and Gaerdenfors(1991),is also given about whether there is a counterpart contraciton in nonmonotonic logic. 相似文献
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We continue the work in Zhu et al. [Normal conditions for inference relations and injective models, Theoret. Comput. Sci. 309 (2003) 287–311]. A class Ω of strict partial order structures (posets, for short) is said to be axiomatizable if the class of all injective preferential models from Ω may be characterized in terms of general rules. This paper aims to obtain some characteristics of axiomatizable classes. To do this, a monadic second-order frame language is presented. The relationship between 0-axiomatizability and second-order definability is explored. Then a notion of an admissible set is introduced. Based on this notion, we show that any preferential model, which does not contain any four-node substructure, must be a reduct of some injective model. Furthermore, we furnish a necessary and sufficient condition for the axiomatizability of classes of injective preferential models using general rules. Finally, we show that, in some sense, the class of all posets without any four-node substructure is the largest among axiomatizable classes. 相似文献
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Li-Yan Yuan 《Journal of Automated Reasoning》1994,13(1):69-82
We study the expressive power of first-order autoepistemic logic. We argue that full introspection of rational agents should be carried out by minimizing positive introspection and maximizing negative introspection. Based on full introspection, we propose the maximal well-founded semantics that characterizes autoepistemic reasoning processes of rational agents, and show that breadth of the semantics covers all theories in autoepistemic logic of first order, Moore's AE logic, and Reiter's default logic. Our study demonstrates that the autoepistemic logic of first order is a very powerful framework for nonmonotonic reasoning, logic programming, deductive databases, and knowledge representation.This research is partially supported by NSERC grant OGP42193. 相似文献
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We consider the problem of integrating Reiter's default logic into terminological representation systems. It turns out that such an integration is less straightforward than we expected, considering the fact that the terminological language is a decidable sublanguage of first-order logic. Semantically, one has the unpleasant effect that the consequences of a terminological default theory may be rather unintuitive, and may even vary with the syntactic structure of equivalent concept expressions. This is due to the unsatisfactory treatment of open defaults via Skolemization in Reiter's semantics. On the algorithmic side, we show that this treatment may lead to an undecidable default consequence relation, even though our base language is decidable, and we have only finitely many (open) defaults. Because of these problems, we then consider a restricted semantics for open defaults in our terminological default theories: default rules are applied only to individuals that are explicitly present in the knowledge base. In this semantics it is possible to compute all extensions of a finite terminological default theory, which means that this type of default reasoning is decidable. We describe an algorithm for computing extensions and show how the inference procedures of terminological systems can be modified to give optimal support to this algorithm.This is a revised and extended version of a paper presented at the3rd International Conference on Principles of Knowledge Representation and Reasoning, October 1992, Cambridge, MA. 相似文献