多Agent合作逻辑研究进展

多Agent合作逻辑(Cooperation Logics)的研究,最近几年以来得到了广泛的关注,是一个前沿研究课题。相关研究成果琳琅满目,其中ATL/ATL*和CL/ECL等开拓性的成果更是倍受瞩目。本文从浩繁的文献中理出交互时序逻辑序列和联盟逻辑序列这两大主线,综述多Agent合作逻辑的研究进展,并对其下一步研究给予展望。     

模糊交互时态逻辑的模型检测

交互时态逻辑已被广泛应用于开放系统的规范描述,交互时态逻辑的模型检测技术是一个比较重要的验证方法。为了形式化描述和验证具有模糊不确定性信息的开放系统的性质,提出了一种模糊交互时态逻辑,并讨论了它的模型检测问题。首先,引入了模糊交互时态逻辑的基于路径和基于不动点的两种语义,证明了其等价性。然后,基于其等价性,给出了模糊交互时态逻辑的模型检测算法和复杂性分析。     

基于线性时序逻辑的多Agent协商推理模型

在多智能体系统中,协商是Agent交互的主要形式.用形式化方法构建了基于线性时序逻辑的协商推理模型,该模型用线性时序逻辑描述在协商过程中Agent所处环境,自身能力、权力、知识、思维等随时间的变化,以及在系统运行时Agent采取异步行为.进一步完善了多Agent系统中自主的协商机制.     

多Agent VSK-AF逻辑

提出了对多Agent系统的信息特征进行推理的形式化体系VSK-AF逻辑，建立了它与多Agent系统的形式化模型间的关系，给出了该逻辑的公理体系和交互公理，证明了该逻辑公理体系的一致性、无矛盾性以及完全性。讨论了进一步的研究工作。     

经验逻辑：一种非单调逻辑的统一形式

人的常识推理是一种充满经验性知识的累积过程,而经验推理具有非单调性。本文提出一种关于典型与例外的经验逻辑,特别研究它的非单调性,它提供了一个现存的主要非单调逻辑的统一基础,这是通过一种类似的规则把它们翻译成经验逻辑获得的。因此,经验逻辑给出了一类更一般而且直观的非单调推理形式。     

知识的非单调处理

演绎逻辑对人类认识世界的处理是单调的,但是在这种基础上建立起来的推理系统与人类对客观世界的认识过程往往是不一致的。非单调逻辑及其推理系统为我们有效地处理人类认识的不完全性提供了一个颇有前途的理论工具。本文简要介绍非单调逻辑的基本问题,并着重讨论三种基本的也是重要的非单调推理形式,即缺省逻辑、模态逻辑和约束推理。     

论辩系统的动态性及其研究进展

论辩系统是一种非单调形式体系,能够支持个体Agent的推理决策和多Agent之间的有效交互.由于个体Agent的知识、观察信息和资源的动态性以及多Agent交互过程的动态性,在各类论辩系统中,论证及其攻击关系的动态性是普遍存在的.作为一个新的研究领域,有关论辩系统动态性的概念、理论和方法远未成熟.在介绍论辩系统相关概念的基础上,阐明论辩系统动态性的两个主要研究方向(正向动态性和逆向动态性),并讨论需要解决的开放性问题.围绕这些问题,简要回顾现有的理论和方法,并分析其特点和不足.     

一种支持自治计算的基于可废止逻辑的柔性Agent

以自治计算的研究为背景,利用可废止逻辑理论的非单调知识表征和推理机制,提出一种能够动态接受规则变更、灵活处理实时发生的规则冲突,并进行高效的非单调推理的柔性Agent模型.这种Agent既是自主的,又是可控的,而且可以在开放、动态的环境中通过合同与其他Agent进行协同工作.     

多Agent合作逻辑中的动作与意图

改进并发博弈结构,给出了一个新模型.消除了不同Agent不准执行相同动作这个与常识不符的假定.给出了5个动作相关函数,使得对Agent、动作与状态三者之间的关系在社会法律约束下的深入考察成为可能.在语法层面同时表述动作和社会法律,提高了多Agent合作逻辑的灵活性和表达能力.在多Agent合作逻辑中引入信念算子和意图算子;考察了两种个体意图和两种群体意图;给出了对命题的个体意图的多子集语义,并把它拓展到对命题的群体意图的语义.     

可更新Datalog的分布式时态逻辑扩展及应用

针对现有的分布式逻辑语言缺乏完整时态表达力等问题,将分布式时态逻辑谓词引入Datalog规则,提出TU-Datalog语言。该语言通过融入U-Datalog的非即时性更新语义,形成完全声明式具有强大时态表达力的逻辑编程语言和环境。通过扩展U-Datalog逻辑固定点语义,提出TU-Datalog语言的固定点时态演化规则,并对该语言的语法、语义、评价算法进行了研究,最后对该语言的应用做了说明和示例。     

基于时态认知逻辑的Web服务模型检测

传统模型检测技术主要采用时态逻辑描述被验证的规范,人们较少注意多智能体认知逻辑的模型检测问题.而在分布式系统领域,系统和协议的规范很适合用认知逻辑来描述.Web服务是一个典型的分布式系统.把Web服务组合建模为多智能体系统,并成功采用我们实现的时态认知逻辑符号模型检测工具MCTK验证了SAS股票分析服务实例.同时采用WSAT,WS-Engineer和SPIN 3个模型检测工具在相同实验环境下验证了该实例,实验结果表明我们的Web服务模型检测方法不仅比这3个模型检测工具更高效,而且支持认知逻辑规范的验证,这是这3个模型检测工具所不具备的.     

Clausal resolution in a logic of rational agency

A resolution based proof system for a Temporal Logic of Possible Belief is presented. This logic is the combination of the branching-time temporal logic CTL (representing change over time) with the modal logic KD45 (representing belief ). Such combinations of temporal or dynamic logics and modal logics are useful for specifying complex properties of multi-agent systems. Proof methods are important for developing verification techniques for these complex multi-modal logics. Soundness, completeness and termination of the proof method are shown and simple examples illustrating its use are given.     

基于Verics的组合Web服务有界模型检测

传统的模型检测技术无法描述系统的认知逻辑特性,而在分布式系统领域,系统和协议的规范适合用多智能体时态认知逻辑来描述.组合Web服务是典型的分布式系统.为了保证组合Web服务运行的正确性,把组合Web服务看成多智能体系统,将其建模成一组相互通信的时间自动机.采用时态认知逻辑模型检测工具Verics对该组合Web服务的可用性、可靠性和时效性的时态认知逻辑特性进行检测.本文以旅游预订系统组合Web服务为例,阐述了上述过程.     

基于组织结构的多主体协作

基于主体组织的多主体问题求解可以降低问题求解难度和交互复杂性,其中多主体组织的形成规则和多主体的协作与规划是多主体合作的关键。文中提出了一种新的多主体组织模型和一组相关的组织原则,给出了组织规划的方法,提出了多主体组织的形成与消亡形式,并利用扩展的时序逻辑和π演算对上述结论进行了形式化描述,完善了基于组织结构的多主体协作理论,改进了多主体理论研究和多主体编程实践之间脱节的现状。     

Annotated Logic Applications for Imperfect Information

Imperfect information is a very general term that comprises different types of information, such as uncertain, vague, fuzzy, inconsistent, possibilistic, probabilistic, partially or totally incomplete information [2]. In the literature of knowledge representation we find a different formal model for each one of these distinct types. For example, annotated logic is a formal model to represent inconsistent information.Annotated logics are non-classical logics introduced in [20] as a logic programming theory. They were proved to be paraconsistent. Based on [5], we present in this work the annotated logic programming theory and some of its applications in Artificial Intelligence (AI). We present it as a formalism to reason with inconsistent information and investigate its possibility to represent other types of imperfect information, such as possibilistic and non-monotonic reasoning. Our main goal is to verify and confirm the importance of annotated logics as a tool for developing knowledge-based and automated reasoning systems in AI.     

Stable and extension class theory for logic programs and default logics

The stable model semantics (cf. Gelfond and Lifschitz [1]) for logic programs suffers from the problem that programs may not always have stable models. Likewise, default theories suffer from the problem that they do not always have extensions. In such cases, both these formalisms for non-monotonic reasoning have an inadequate semantics. In this paper, we propose a novel idea-that of extension classes for default logics, and of stable classes for logic programs. It is shown that the extension class and stable class semantics extend the extension and stable model semantics respectively. This allows us to reason about inconsistent default theories, and about logic programs with inconsistent completions. Our work extends the results of Marek and Truszczynski [2] relating logic programming and default logics.     

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.     

Stochastic game logic

Stochastic game logic (SGL) is a new temporal logic for multi-agent systems modeled by turn-based multi-player games with discrete transition probabilities. It combines features of alternating-time temporal logic (ATL), probabilistic computation tree logic and extended temporal logic. SGL contains an ATL-like modality to specify the individual cooperation and reaction facilities of agents in the multi-player game to enforce a certain winning objective. While the standard ATL modality states the existence of a strategy for a certain coalition of agents without restricting the range of strategies for the semantics of inner SGL formulae, we deal with a more general modality. It also requires the existence of a strategy for some coalition, but imposes some kind of strategy binding to inner SGL formulae. This paper presents the syntax and semantics of SGL and discusses its model checking problem for different types of strategies. The model checking problem of SGL turns out to be undecidable when dealing with the full class of history-dependent strategies. We show that the SGL model checking problem for memoryless deterministic strategies as well as the model checking problem of the qualitative fragment of SGL for memoryless randomized strategies is PSPACE-complete, and we establish a close link between natural syntactic fragments of SGL and the polynomial hierarchy. Further, we give a reduction from the SGL model checking problem under memoryless randomized strategies into the Tarski algebra which proves the problem to be in EXPSPACE.     

Nonmonotonic logic and temporal projection

Nonmonotonic formal systems have been proposed as an extension to classical first-order logic that will capture the process of human “default reasoning” or “plausible inference” through their inference mechanisms, just as modus ponens provides a model for deductive reasoning. But although the technical properties of these logics have been studied in detail and many examples of human default reasoning have been identified, for the most part these logics have not actually been applied to practical problems to see whether they produce the expected results.We provide axioms for a simple problem in temporal reasoning which has long been identified as a case of default reasoning, thus presumably amenable to representation in nonmonotonic logic. Upon examining the resulting nonmonotonic theories, however, we find that the inferences permitted by the logics are not those we had intended when we wrote the axioms, and in fact are much weaker. This problem is shown to be independent of the logic used; nor does it depend on any particular temporal representation. Upon analyzing the failure we find that the nonmonotonic logics we considered are inherently incapable of representing this kind of default reasoning.The first part of the paper is an expanded version of one that appeared in the 1986 AAAI proceedings. The second part reports on several responses to our result that have appeared since the original paper was published.