扩充逻辑程序设计的R－演算──知识库维护的操作方法

本文首先介绍了知识库维护过程中诸如知识库序列、新规则、用户反驳以及重构等概念；然后给出了一个扩充逻辑程序设计的框架，在这一框架下，每个逻辑程序等价于一个知识库；进一步定义了一个转换系统，称为扩充逻辑程序设计的Ｒ－演算，对一个给定的知识库和用户反驳，此演算可以导出知识库的最佳修正；同时证明了该演算的可靠性和完备性；另外，对本文的工作与其他相关工作进行了比较；最后，给出了本文的结论．     

A Logical Framework for Knowledge Base Maintenance

1IntroductionAmongalltheoreticalworksonknowledgebasemaintenance,Doyle's"TruthMaintenanceSystem"[1]andAlchourr6n,GdrdenforsandMakinson's"LogicofThe-oryChange"[2]playthemostimportantrole.'Inthe"TruthMaintenanceSystem",everylawcontainedinaknowledgebase,orabaseforshort,isspecifiedby"in"and"out"status,whichindicatethededuciblerelationsbetweenthelawsofthebase.Whenalawofthebaseisrejectedbytheusers3arevisedversionofthebasecanbeobtainedbymechanicallychangingthe"in"and"out"statusofthelaws.Thismech…     

知识库维护过程中检查其协调性的有效方法

本文首先描述了知识库维护过程中的协调性问题，然后给出了扩充逻辑程序设计的框架，在此框架下，每个逻辑程序等价于一个知识库．为了检查知识库的协调性，本文为知识库中的推理规则构造了正支持集和负支持集，并给出了一些定义；基于这些概念和定义，提出了知识库维护过程中检查知识库协调性的一种有效方法，并证明了相关的定理；基于此方法，实现了一个算法ＣＨＩＭＥ，并给出了用ＣＨＩＭＥ分析一些知识库的实验结果．本文还提到一些相关的工作，最后给出结论.     

开放逻辑中基于一优先序的R-重构

在开放逻辑中,Ｒ－重构作为一知识库或信念集修正的结果并不唯一,有时甚至太多而难于明确计算和表示,为此,文中给出了基于一优先序的Ｒ－重构的概念,基于一优先序的Ｒ－重构往往要比Ｒ－重构少得多,不存在上述Ｒ－重构的问题,在用户给出的关于一知识库中知识的优先序时,基于该优先序的Ｒ－重构可以用来刻画对该知识库的合理维护。     

Operational and complete approaches to belief revision

Two operational approaches to belief revision are presented in this paper.The rules of R-calculus are modified in order to deduce all the maximal consistent subsets.Another set of given in order to deduce all the minimal inconsistent subsets.Then a procedure,which can generate all the maximal consistent subsets,is presented.They are complete approaches,since all the maximal consistent subsets can be deduced or generated.In this paper,only the case of propositional logic is considered.     

基于强相关逻辑的不精确应急时态知识表示

在强相关逻辑基础上扩展不精确时态关系,以满足不精确应急时态知识表示与推理的需要。给出了粗糙集及强相关逻辑的相关概念;通过定义不精确时态关系扩展了强相关逻辑,形成了粗糙时态强相关逻辑,给出了可靠性和完备性证明;通过实际例子说明粗糙时态强相关逻辑的知识表示和应用。结果表明扩展后的粗糙时态强相关逻辑可以实现不精确时态知识的表示与推理。     

基于粗糙描述逻辑的不精确时态知识表示研究

在粗糙描述逻辑基础上扩充不精确时态关系,以满足不精确时态知识表示与推理的需要。首先给出了粗糙集及粗糙描述逻辑的相关概念;接着通过定义粗糙时态描述逻辑不精确时态关系,扩展了粗糙描述逻辑中具体域,并给出了可靠性和完备性证明;最后通过实际例子说明粗糙时态描述逻辑的知识表示和应用,结果表明扩展后的粗糙时态描述逻辑可以实现不精确时态知识的表示与推理。     

基于知识Petri网和归结规则的推理方法

本文提出了一种基于知识Petri网和归结规则的推理方法.通过知识Petri网描述命题逻辑知识库,将归结规则映射到知识Petri网上,根据库所和变迁的连接关系,定义了知识Petri网中的归结结构.利用归结结构,给出了基于知识Petri网的归结推理算法和扩展知识库的推理算法,并利用Wumpus实例验证了推理算法.该推理方法是可靠且完备的,能够利用知识Petri网的网络结构降低计算复杂性.     

面向数据库中关系的描述逻辑

给出了两个面向数据库中关系的描述逻辑。在其中一个描述逻辑中,一个关系可以表示为一个知识库和这个知识库的模型,并且对于这个知识库的任意模型,都存在一个与该关系同构的子模型;在另一个描述逻辑中,一个关系可以表示为一个知识库和这个知识库的模型,以便这个知识库的任何模型都同构于这个关系。     

基于描述逻辑的模糊ER模型的表示与推理

重点分析了将ER模型分别转化为描述逻辑ALNUI知识库和DLR知识库的不同之处.在深入研究了描述逻辑DLR的基础之上,对DLR进行了模糊化扩展,提出了一种新的模糊描述逻辑FDLR(fuzzyDLR).定义了FDLR的语法结构、语义解释以及知识库的形式,研究了如何将模糊ER模型转化为FDLR的知识库.通过一个转化实例例证了FDLR能够很好地对模糊ER模型进行表示,并利用FDLR的推理机制研究了模糊ER模型的自动推理问题,同时给出了上述转化和推理问题的正确性证明.     

A Logical Framework for Knowledge Base Maintenance

The maintenance sequences of a knowledge base and their limits are introduced.Some concepts used in knowledge base maintenance,such as new laws,user‘s rejections,and reconstructions of a knowledge base are defined;the related theorems are proved.A procedure is defined using transition systems;it generates maintenance sequences for a given user‘s model and a knowledge base.It is proved that all sequences produced by the procedure are convergent,and their limit is the set of true sentences of the model.Some computational aspects of reconstructions are studied.An R-calculus is given to deduce a reconstruction when a knowledge base meets a user‘s rejection.The work is compared with AGM‘s theory of belief revision.     

扩展的动态逻辑程序及其在产品个性化推荐中的应用

动态逻辑程序能很好的处理知识库更新问题, 但它不能描述和处理具有偏好的知识更新问题. 因此, 本文在动态逻辑程序的基础上, 提出了一种新的扩展的动态逻辑程序, 它通过对规则头部使用有序析取的方法使其能够描述和处理具有偏好的知识更新问题, 进一步增强了知识的表达和推理能力, 并且定义了其最优回答集语义. 同时将这种新的扩展的动态逻辑程序应用于产品推荐系统中, 使用户获得的推荐信息具有个性化特点, 达到个性化推荐的目的. 最后以一个产品个性化推荐实例讨论扩展的动态逻辑程序在产品个性化推荐中的应用.     

Formalizing multiple interpretation of legal knowledge

A representation methodology for knowledge allowing multiple interpretations is described. It is based on the following conception of legal knowledge and its open texture. Since indeterminate, legal knowledge must be adapted to fit the circumstances of the cases to which it is applied. Whether a certain adaptation is lawful or not is measured by metaknowledge. But as this too is indeterminate, its adaptation to the case must be measured by metametaknowledge, etc. This hierarchical model of law is quite well-established and may serve well as a basis for a legal knowledge system. To account for the indeterminacy of law such a system should support the construction of different arguments for and against various interpretations of legal sources. However, automatizing this reasoning fully is unsound since it would imply a restriction to arguments defending interpretations anticipated at programming time. Therefore, the system must be interactive and the user's knowledge be furnished in a principled way. Contrary to the widespread opinion that classical logic is inadequate for representing open-textured knowledge, the framework outlined herein is given a formalization in first order logic.     

分析安全协议猜测攻击的模态逻辑方法

以CKT5逻辑为基础,对其进行了多方面重要的扩展;在原有对称密钥机制的基础上,增加了公开密钥机制和vernam加密机制以增强其描述协议的能力;打破完善加密假设,给出了一组定义和规则使主体具备猜测和验证口令的能力;给出了与在线猜测攻击相关的定理以反映在线猜测攻击的特点;通过相关引理和定理的证明,简化了猜测攻击的分析过程,使该文方法比现有方法更加简洁高效.扩展后的逻辑能够用于分析安全协议的猜测攻击,包括在线猜测攻击.     

多智体系统时态认知规范的模型检测算法

模型检测技术一直以来主要是检验用时态逻辑描述的规范,人们很少注意认知逻辑的模型检测问题,而在分布式系统领域,系统和协议的规范已广泛地采用知识逻辑来描述.着重研讨了时态认知逻辑的模型检测算法.在SMV(symbolic model verifier)模型检测器的基础上,根据知识的语义和集合理论,提出了多种检验知识和公共知识的算法,从而使SMV的检测功能由时态逻辑扩充到时态认知逻辑.这些方法也适用于其他以状态集合作为输出的模型检测方法和工具的功能扩充.     

面向自然交互的多通道人机对话系统中答句自动生成方法

多通道自然人机对话系统要求计算机能够对用户的语句产生智能应答,传统的人机对话系统由于知识库的限制以及用户话语的随意性,当对话内容超出知识库范围时,系统将无法应答或产生与用户期望不符的回答,这在一定程度上影响了人机对话系统用户的体验感.为了解决该问题,提出了一种融合多模态历史交互信息和面向数据的句法分析(data-oriented parsing,简称DOP)模型的最优答句生成方法:首先从大规模句法树库中提取上下文无关文法的语法规则,然后结合对话过程中用户呈现的表情、姿态等多模态历史交互信息,融合DOP模型对上下文无关文法生成的汉语句子进行过滤,最终生成一个符合语法规则且符合语义的答句返回给用户,让计算机在无法获得知识库支撑时,根据交互历史信息生成应对当前对话的语句,有效地提升了多通道自然人机交互系统用户的体验感.该方法应用于交通信息查询以及咖啡厅的多主题多模态人机自由对话系统.用户的体验表明,该方法能够有效提高用户交互的自然度和体验感.     

Outlier detection using default reasoning

Default logics are usually used to describe the regular behavior and normal properties of domain elements. In this paper we suggest, conversely, that the framework of default logics can be exploited for detecting outliers. Outliers are observations expressed by sets of literals that feature unexpected semantical characteristics. These sets of literals are selected among those explicitly embodied in the given knowledge base. Hence, essentially we perceive outlier detection as a knowledge discovery technique. This paper defines the notion of outlier in two related formalisms for specifying defaults: Reiter's default logic and extended disjunctive logic programs. For each of the two formalisms, we show that finding outliers is quite complex. Indeed, we prove that several versions of the outlier detection problem lie over the second level of the polynomial hierarchy. We believe that a thorough complexity analysis, as done here, is a useful preliminary step towards developing effective heuristics and exploring tractable subsets of outlier detection problems.     

Fuzzy logic techniques in multimedia database querying: apreliminary investigation of the potentials

Fuzzy logic is known for providing a convenient tool for interfacing linguistic categories with numerical data and for expressing user's preference in a gradual and qualitative way. Fuzzy set methods have been already applied to the representation of flexible queries and to the modeling of uncertain pieces of information in databases systems, as well as in information retrieval. This methodology seems to be even more promising in multimedia databases which have a complex structure and from which documents have to be retrieved and selected not only from their contents, but also from “the idea” the user has of their appearance, through queries specified in terms of user's criteria. This paper provides a preliminary investigation of the potential applications of fuzzy logic in multimedia databases. The problem of comparing semistructured documents is first discussed. Querying issues are then more particularly emphasized. We distinguish two types of request, namely, those which can be handled within some extended version of an SQL-like language and those for which one has to elicit user's preference through examples