A skeptical theory of inheritance in nonmonotonic semantic networks

Horty, John F.; Thomason, Richmond H.; Touretzky, David S.

doi:10.1016/0004-3702(90)90057-7

Cited by 147 publications

(92 citation statements)

References 13 publications

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“…5 Although, as far as I know, this example was first published in the textbook cited here, it had previously been part of the oral tradition for many years-I first heard it during the question session after the AAAI-87 presentation of [6], when Ginsberg raised it as an objection to that theory.…”

Section: Floating Conclusionmentioning

confidence: 99%

“…6 It is harder to see how floating conclusions could be avoided in model-preference logics. In a circumscriptive theory, for instance, the yacht example could naturally be expressed by supplementing the facts Considered from the standpoint of default logic, the situation could then be represented through the new default theory ∆ = W, D , with…”

Section: Comments On the Examplementioning

confidence: 99%

“…As a policy for reasoning with conflicting defaults, the notion of skepticism was originally 28 introduced into the field of nonmonotonic logic to characterize the particular system presented in [6], which did not involve the assumption that one of a theory's multiple extensions must be correct, and did not support floating conclusions. By now, however, the term is used almost uniformly to describe approaches that do rely on this assumption, so that the "skeptical conclusions" of a theory are generally identified as the statements supported by each of its multiple extensions, including the floating conclusions.…”

Section: Skepticismmentioning

confidence: 99%

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Skepticism and floating conclusions

Horty

2012

Reasons as Defaults

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Section: Floating Conclusionmentioning

confidence: 99%

Section: Comments On the Examplementioning

confidence: 99%

Section: Skepticismmentioning

confidence: 99%

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Skepticism and floating conclusions

Horty

2012

Reasons as Defaults

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“…In general, however, path-based inheritance theories lack model-theoretic semantics. Previous pathbased theories of inheritance include the work of Touretzky, Horty, and Thomason [18,17,19,38,39,40,41], Sandewall [32], and Geffner and Verma [14].…”

Section: A Path-based Definitionmentioning

confidence: 99%

Resolving ambiguity in nonmonotonic inheritance hierarchies

Stein

1992

Artificial Intelligence

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Sis estimated to average 1 hour 9eo eidorse. . incldiunq the time for reviewing. intrucions. searching exsting data This paper describes a theory of inheritance theories. We present an original theory of inheritance in nonmonotonic hierarchies. The structures on which this theory is based delineate a framework that subsumes most inheritance theories in the literature, providing a new foundation for inheritance. "* Our path-based theory is sound and complete w.r.t. a direct model-theoretic semantics."* Both the credulous and the skeptical conclusions of this theory are polynomial-time computable."* We prove that true skeptical inheritance is not contained in the language of path-based inheritance.Because our techniques are modular w.r.t. the definition of specificity, they generalize to provide a unified framework for a broad class of inheritance theories. By describing multiple inheritance theories in the same "language" of credulous extensions, we make principled comparisons rather than the ad-hoc examination of specific examples makes up most of the comparative inheritance work. IntroductionInheritance reasoning is ubiquitous. Hierarchies provide a concise encoding of much of our comrmonsense knowledge. They appear in various guises in the literature of artificial intelligence, but also throughout the various arts and sciences. Open nearly any textbook, and some hierarchy is likely to appear. Reasoning with inheritance hierarchies is of particular interest to the artificial intelligence community because hierarchies are not only useful and native to human reasoning, but also simple and often tractable. The simplicity of the "inheritance problem" makes it attractive as a topic that can be considered in its entirety; its tractability makes it practical for the implementation of knowledge representation systems.In this paper, we present several equivalent formulations of inheritance reasoning. Each approach may be useful in a particular context; by demonstrating their equivalence, we show that the most appropriate definition may be chosen. The techniques that we develop here generalize to a broad class of existing systems, providing a unified foundation for inheritance theory and a basis for comparative analysis, as well as extending previous results.We begin, in section 2, by providing an intuitive description of what we intend by inheritance reasoning. We view inheritance hierarchies as representing primitive assertions in the knowledge base of some reasoning agent, and the inheritance problem as that of determining the agent's derived beliefs. The work in the remainder of this paper builds on this foundation.In section 3, we give a formal path-based definition of inheritance. A path-based inheritance theory gives rules describing the admissible conclusions of a hierarchy. The theory presented here combines rules concerning the transitivity of primitive assertions with an ambiguity-resolution criterion to be invoked when two paths conflict. We describe the transitivity component by the notion of reachability; ...

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“…The chaining sfc allows to manage the application of conflicting rules (i.e. those whose conclusions are opposed) according to the same intuition as the one in inheritance networks and which is expressed by the rule of preemption [5]. The practical use of sfc is presented through the three chaining methods: forward chaining, backward chaining and mixed chaining.…”

Section: Introductionmentioning

confidence: 99%

On Some Inferences Based on Stratified Forward Chaining: An Application to E-Government

Bezzazi

2007

Advances in Information Systems Development

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Summary. This paper introduces first an expert system shell based on stratified forward chaining. The stratified forward chaining was proposed as a generalization for the inheritance networks with exception since it allows more than one antecedent in the premises part of a rule. Expert systems built with this tool are rule based and the user interface is web based. The practical use of this chaining is presented here through the three chaining methods: forward chaining, backward chaining and mixed chaining. Our current aim is to make use of these inference mechanisms to help the user in his interaction with administration to identify in an efficient way the relevant information he needs. This is done through a question-response dialog to determine the user profile. The paper considers also in a second part a special kind of inference called deontic inference. The rationale behind this kind of inference is the possible presence of deontic rules which may impose a change in the base of current facts to make it comply with the obligations they prescribe.

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A skeptical theory of inheritance in nonmonotonic semantic networks

Abstract: This paper describes a new approach to inheritance reasoning in semantic networks

Cited by 147 publications

References 13 publications

Skepticism and floating conclusions

Skepticism and floating conclusions

Resolving ambiguity in nonmonotonic inheritance hierarchies

On Some Inferences Based on Stratified Forward Chaining: An Application to E-Government

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