一种基于可信度的迭代信念修正方法

信念修正主要解决在接收到新信息时,如何对原有知识库进行操作的问题．经典的迭代信念修正主要关注信念修正的一致性,并未考虑多agent系统中信息具有不可靠性,以及信念修正过程对修正结果的影响．基于可信度的迭代信念修正方法,通过证据理论以及信度函数方法估计信息的可信度,并由此确定最优的最大协调子集作为信念修正的结果．基于可信度的迭代信念修正算子具有历史依赖性,即修正结果不仅与当前的信念集和接收到的新信息有关,也与信念集中曾经接收到的信息相关．     

不一致信念的定量非修正方法满足AGM公设的讨论

常识推理的核心问题为信念修正问题，研究人员就此已经提出了许多方法，其中AGM理论是最有影响的一个。本文讨论并逐条证明了定量非修正方法满足AGM公设的情况，表明该方法是一种性质良好的信念修正方法。     

弱化矛盾信息的一种修正方法

信念修正中一个关键的问题就是对不一致信息的处理。文中提出一种新的策略，在对不一致信息的处理过程中，通过弱化矛盾信息而不是完全丢弃来维护知识库的一致性。这种方法遵循了最小改变原则，使信息丢失尽可能小从而保留了更多的有用信息。并讨论了其性质及满足AGM公设的情况。     

有缺指派下的信念修正逻辑

经典的AGM信念修正理论和以D-P假设为代表的迭代信念修正理论都是以完全指派为可能世界而进行的理论研究.把这些研究推广到有缺指派的领域中与完全指派为每个原子命题符号都指派真假值不同,有缺指派是一个三值指派,它可以为每个原子命题符号指派真、假和不确定三值之一.以有缺指派为可能世界,对D-P系统进行了推广,证明了相应的表示定理.     

一种基于遗忘理论的信念收缩方法

针对在经典信念理论框架下,信念收缩后可能出现信息损失的问题,本文提出了一种利用遗忘理论来构建收缩算子的信念收缩方法。本文先通过理论证明来说明该收缩算子能够满足AGM理论中信念收缩的假定,然后用实例说明,与命题逻辑表示的信念遗忘收缩相比,一阶谓词逻辑表示的信念遗忘收缩保留了更多的原有信息,避免了不必要的信息损失,遵循最小修改原则。     

弱化矛盾信息的一种修正方法

信念修正中一个关键的问题就是对不一致信息的处理.文中提出一种新的策略,在对不一致信息的处理过程中,通过弱化矛盾信息而不是完全丢弃来维护知识库的一致性.这种方法遵循了最小改变原则,使信息丢失尽可能小从而保留了更多的有用信息.并讨论了其性质及满足AGM公设的情况.     

智能体行动推理中的信念修正

信念修正中的加强修正算法在保留低秩非矛盾信念时存在不足,流演算由于其表示公式的局限,无法较好的与信念修正结合来进行行动推理。针对以上不足,提出了依赖信念修正算法和Strategy-Axiom-Reasoning模型。该算法满足Ind假设并且较好的保留了条件信念和低秩非矛盾信念,SAR模型继承并改进了流演算的公理系统,用公式集表示信念集,较好的实现了与信念修正的结合。最后将依赖信念修正算法运用到SAR模型中,用实验证明了其可行性。     

有限信念集上修正的一种方法

讨论了信念集是有限子句集时的信念修正方法.首先给出了一阶逻辑上求所有极小不协调子集的一个过程,证明了该过程的正确性;然后讨论了由有极小不协调的子集来实现信念修正的方法,介绍所开发的信念修正的原型系统;最后与相关工作进行了比较.     

Agent信念的遗忘修正方法

为了使信念修正能够满足最小改变原则,首先基于遗忘理论定义遗忘收缩算子,并且证明该算子满足必要AGM收缩假定;然后通过Levi Identity构建遗忘修正算子;最后给出遗忘修正方法和多次遗忘修正算法。实例分析表明,算法具有可行性和有效性,能够得到较满意的修正结果。     

信念修正的一种数据结构--LAT

1前言 信念修正(Belief Revision)是研究知识进化过程的一种理论方法.20世纪80年代,瑞典著名哲学家、人工智能专家Alchourrón和其同事G(a)rdenfors与Makinson发展起来的AGM理论[1](或称AGM假设)是比较典型也是比较完整的信念修正体系,并且在知识工程、演绎数据库、逻辑程序理论等领域的研究中获得非常有意义的应用,深受国际人工智能界的关注.     

A Thorough Axiomatization of a Principle of Conditional Preservation in Belief Revision

Although the crucial role of if-then-conditionals for the dynamics of knowledge has been known for several decades, they do not seem to fit well in the framework of classical belief revision theory. In particular, the propositional paradigm of minimal change guiding the AGM-postulates of belief revision proved to be inadequate for preserving conditional beliefs under revision. In this paper, we present a thorough axiomatization of a principle of conditional preservation in a very general framework, considering the revision of epistemic states by sets of conditionals. This axiomatization is based on a nonstandard approach to conditionals, which focuses on their dynamic aspects, and uses the newly introduced notion of conditional valuation functions as representations of epistemic states. In this way, probabilistic revision as well as possibilistic revision and the revision of ranking functions can all be dealt with within one framework. Moreover, we show that our approach can also be applied in a merely qualitative environment, extending AGM-style revision to properly handling conditional beliefs.     

A survey of multiple contractions

The AGM theory of belief contraction is extended tomultiple contraction, i.e. to contraction by a set of sentences rather than by a single sentence. There are two major variants: Inpackage contraction all the sentences must be removed from the belief set, whereas inchoice contraction it is sufficient that at least one of them is removed. Constructions of both types of multiple contraction are offered and axiomatically characterized. Neither package nor choice contraction can in general be reduced to contractions by single sentences; in the finite case choice contraction allows for reduction.     

Infobase Change: A First Approximation

Generalisations of theory change involving operations on arbitrary sets ofwffs instead of on belief sets (i.e., sets closed under a consequencerelation), have become known as base change. In one view, a base should bethought of as providing more structure to its generated belief set, whichmeans that it can be employed to determine the theory contraction operationassociated with a base contraction operation. In this paper we follow suchan approach as the first step in defining infobase change. We think of an infobase as a finite set of wffs consisting of independently obtainedbits of information. Taking AGM theory change (Alchourrón et al. 1985) as the general framework, we present a method that uses the structure of aninfobase B to obtain an AGM theory contraction operation for contractingthe belief set Cn(B). Both the infobase and the obtained theory contraction operation then play a role in constructing a unique infobasecontraction operation. Infobase revision is defined in terms of an analogueof the Levi Identity, and it is shown that the associated theory revisionoperation satisfies the AGM postulates for revision. Because every infobaseis associated with a unique infobase contraction and revision operation, the method also allows for iterated base change.     

Dynamic belief revision operators

The AGM approach to belief change is not geared to provide a decent account of iterated belief change. Darwiche and Pearl have sought to extend the AGM proposal in an interesting way to deal with this problem. We show that the original Darwiche-Pearl approach is, on the one hand excessively strong and, on the other rather limited in scope. The later Darwiche-Pearl approach, we argue, although it addresses the first problem, still remains rather permissive. We address both these issues by (1) assuming a dynamic revision operator that changes to a new revision operator after each instance of belief change, and (2) strengthening the Darwiche-Pearl proposal. Moreover, we provide constructions of this dynamic revision operator via entrenchment kinematics as well as a simple form of lexicographic revision, and prove representation results connecting these accounts.     

信念修正的完全和可操作的方法

给出了命题逻辑上信念修正的两种可操作的完全方法.首先对R-演算的规则进行了修改,使得对任何一个极大协调的子集都通过这组规则得到.然后,给出了求得所有的极小不协调子集的一组规则.最后,给出一个过程,该过程能求得所有的极大协调子集.因为这两种方法都能求得所有的极大协调子集,所以把它们称为完全的.     

一种劝说式多Agent多议题协商方法

多Agent系统中的协商问题往往由许多议题组成,导致问题空间十分庞大．传统的协商方法通过对问题空间进行穷尽搜索来找到最优解,并不适合多议题协商．而且,传统的方法不考虑协商偏好变化的情况,使得Agent在不完全及不正确环境下找到的最优解并不合理．提出一种劝说式多Agent多议题协商方法．借助信念修正这一有效的推理工具,协商Agent能够在协商过程中接受协商对手的劝说,考虑对手对协商议题的偏好,并根据一种基于辩论的信念修正方法调整自身的偏好．这样就能够使协商Agent对变化的协商环境具备适应性,从而提高协商的效率及正确率,快速准确地达成协议．     

A Power Algebra for Theory Change

Various representation results have been established for logics of belief revision, in terms of remainder sets, epistemic entrenchment, systems of spheres and so on. In this paper I present another representation for logics of belief revision, as an algebra of theories. I show that an algebra of theories, enriched with a set of rejection operations, provides a suitable algebraic framework to characterize the theory change operations of systems of belief revision. The theory change operations arise as power operations of the conjunction and disjunction connectives of the underlying logic.