一种基于时态的扩展值辩论框架

时间是用来描述辩论过程以及辩论活动变化的一个重要因素,在辩论框架中加入时间因素是积极的。本文结合Dung的标准辩论框架以及Bench-Capon的基于值的辩论框架,提出了基于时态的扩展值辩论框架。首先分析了Dung的辩论框架以及Bench-Capon的值辩论框架在时态以及辩论值方面描述的局限性及需求,然后结合这些需求提出了基于时态的扩展值辩论框架,给出了完整的框架结构和语义描述,证明了基于时态的扩展值辩论框架满足Dung提出的标准辩论框架的一些基本定理。     

辩论的理论模型及其算法研究

本文研究分布式人工智能背景下的辩论的理论模型及其算法,提出并建立了一个基于命题性知识的辩论的理论框架.在此框架下,我们给出了几个体现不同辩论策略的辩论算法,并对算法的正确性给出了理论证明.本文的研究可为分布式人工智能中多专家系统的辩论和意见综合提供参考,进一步的研究可望推进多专家联合系统的实用化进程.     

基于可信度的辩论模型及争议评价算法

辩论是智能主体间为了消除分歧的一种基于言语的交互行为.由于知识的局限性,争议以及争议内部的陈述通常存在不确定性,因此在对辩论进行建模时需要考虑不确定信息处理问题.提出一种基于可信度的辩论模型（CFA）,该模型将争议表示为由若干前提和一个结论组成的可废止规则,并用对话树描述辩论推演过程.为了表示不确定性推理,引入可信度模型,将争议前提的不确定性和争议之间的攻击强度统一用可信度因子表示.在此基础上,提出计算陈述可信度的争议评价算法,并通过设定可信度阈值确定陈述的可接受性,得出最终辩论结果.最后,用一个实例说明该方法的有效性.该模型可以有效处理不确定信息条件下辩论推理过程,其辩论算法建立在数值计算基础之上,所得出的可接受陈述集在给定可信度阈值条件下是唯一的,可以克服Dung 的抽象辩论框架中扩充语义的不足.     

基于逻辑和辩论的安全策略一致性研究

冲突检测和冲突消解是策略一致性研究的两个主要方向。现有的冲突检测算法时间复杂度高,且缺乏灵活性和扩展性。改变策略条件和基于优先级的冲突消解方法容易引起新的不一致性问题,而且优先权的赋予带有主观因素,难以实现。在此基础上,使用逻辑对策略和策略冲突进行形式化描述和分析,并提出了一种基于逻辑合一思想的多项式时间内的策略一致性检测算法;把策略冲突分为包容冲突、相交冲突和互补冲突,给出了一种包容冲突和相交冲突的自动解决方法,证明了该方法的可行性和完备性;利用辩论机制和理论对策略互补冲突进行了语义分析,为基于优先级的解决方案提供了理论基础;提出了一种策略互补冲突下的一致性策略子集的计算算法,并进行了复杂度分析。     

一种扩展双极辩论模型

提出一种扩展双极辩论模型EBAF(extended bipolar argumentation framework).该模型不仅包括攻击和支援两种独立的语义关系,还允许攻击和支援的递归交互,即对攻击和支援关系进行攻击或支援,且递归次数不受限制.围绕该模型的可接受集合的确定问题,首先将该模型中的攻击和支援关系进行分离,得到攻击辩论框架和支援辩论框架;然后将攻击关系和支援关系作为实体,把递归攻击和递归支援转化为关系视角下的攻击和支援.在此基础上,定义了EBAF的基本语义概念和可接受集合,并给出了可接受集合的确定算法.最后将EBAF与其他相关辩论模型进行了比较.     

面向领域的语义搜索引擎的应用研究

针对基于关键字的搜索引擎缺乏语义的问题,提出了一种面向专业领域的语义搜索引擎模型.以领域本体形式化描述为基础,构建本体语义框架,进而给出语义搜索模型.在模型中,以概念、概念-实例以及关键字等3种扩展特征项作为基础,对查询扩展算法和文档语义标注算法进行了研究,并且构建了语义索引,通过引入向量空间模型判定扩展检索词与语义文档的相似度.实验结果表明,该模型较传统模型较大提高了检索的查准率和查全率.     

基于消息的构件组合运算与构件演化

根据构件能够接收和发送的消息，扩展了构件接口定义框架，给出了基于消息的构件组合模型，定义了构件的执行路径，对四种组合运算进行了形式化描述，提出并证明了六则构件演化运算．给出了一个实例：把一个没有显示语义的层次系统模型简化为语义明确的树形组合模型，并给出了模型的代数表达式和简化算法．     

一种新的辩论推理模式及其应用

文中定义了一个新的辩论推理模式,建立了一个形式化的知识表示框架,并把它应用于研究扩展逻辑程序类的说明语义,结果表明,新语义克服了择优语义的不足。作者还根据上述研究结果实现了逻辑程序设计风格下的知识框架。     

用于计算辩论的论据本体研究

近年来辩论技术在人工智能领域获得广泛关注。然而,在辩论过程中,如何高质高效地构建攻击论据仍然是难以解决的问题。通过分析论据的本质属性,形式定义论据的相关概念及相互关系,结构化论据的知识表示,实现了论据本体的建模。该论据本体的一致性和可用性通过一个辩论实例得以验证。在此基础上构建了一个原型系统,该系统能够在辩论过程中基于论据本体查找和构建论据,重用已构建的论据,从而有效提高了自动辩论的计算效率。     

基于价值辩论框架的决策支持技术研究

在复杂、开放、不确定的环境中,决策者都面临着对行动方案进行论证与选择的难题.基于辩论的决策支持技术是近年来出现的不同于传统辅助决策理论的新方法,它使用论据辅助决策制定和解释决策的理由.首先总结分析了当前基于价值辩论框架的决策支持模型存在的不足与缺陷,提出了论据分类的思想,然后根据该思想设计了ArguDecision辩论...     

Coalitions of arguments: A tool for handling bipolar argumentation frameworks

Bipolar argumentation frameworks enable to represent two kinds of interaction between arguments: support and conflict. In this paper, we turn a bipolar argumentation framework into a meta‐argumentation framework where conflicts occur between sets of arguments, characterized as coalitions of supporting arguments. So, Dung's well‐known semantics can be used on this meta‐argumentation framework to select the acceptable arguments. © 2009 Wiley Periodicals, Inc.     

A logic of argumentation for specification and verification of abstract argumentation frameworks

In this paper, we propose a logic of argumentation for the specification and verification (LA4SV) of requirements on Dung??s abstract argumentation frameworks. We distinguish three kinds of decision problems for argumentation verification, called extension verification, framework verification, and specification verification respectively. For example, given a political requirement like ??if the argument to increase taxes is accepted, then the argument to increase services must be accepted too,?? we can either verify an extension of acceptable arguments, or all extensions of an argumentation framework, or all extensions of all argumentation frameworks satisfying a framework specification. We introduce the logic of argumentation verification to specify such requirements, and we represent the three verification problems of argumentation as model checking and theorem proving properties of the logic. Moreover, we recast the logic of argumentation verification in a modal framework, in order to express multiple extensions, and properties like transitivity and reflexivity of the attack relation. Finally, we introduce a logic of meta-argumentation where abstract argumentation is used to reason about abstract argumentation itself. We define the logic of meta-argumentation using the fibring methodology in such a way to represent attack relations not only among arguments but also among attacks. We show how to use this logic to verify the requirements of argumentation frameworks where higher-order attacks are allowed [A preliminary version of the logic of argumentation compliance was called the logic of abstract argumentation?(2005).]     

Reasoning about preferences in argumentation frameworks

The abstract nature of Dung's seminal theory of argumentation accounts for its widespread application as a general framework for various species of non-monotonic reasoning, and, more generally, reasoning in the presence of conflict. A Dung argumentation framework is instantiated by arguments and a binary conflict based attack relation, defined by some underlying logical theory. The justified arguments under different extensional semantics are then evaluated, and the claims of these arguments define the inferences of the underlying theory. To determine a unique set of justified arguments often requires a preference relation on arguments to determine the success of attacks between arguments. However, preference information is often itself defeasible, conflicting and so subject to argumentation. Hence, in this paper we extend Dung's theory to accommodate arguments that claim preferences between other arguments, thus incorporating meta-level argumentation based reasoning about preferences in the object level. We then define and study application of the full range of Dung's extensional semantics to the extended framework, and study special classes of the extended framework. The extended theory preserves the abstract nature of Dung's approach, thus aiming at a general framework for non-monotonic formalisms that accommodate defeasible reasoning about as well as with preference information. We illustrate by formalising argument based logic programming with defeasible priorities in the extended theory.     

基于动态规划的优先语义扩充求解算法

抽象辩论框架中的优先语义是判断争议可接受程度的最重要语义。现有优先扩充求解方法多用标记映射求解,依赖于标记的定义、转换规则、相邻争议的标记。算法每次迭代会产生一个新的抽象辩论框架导致时间、空间复杂度较高。提出一种基于动态规划的优先扩充算法,在动态规划中加入争议可接受性判断,求出辩论框架中极大可容许集得到优先扩充。在基于随机抽象辩论框架与ICCMA提供的数据集进行实验,同Heureka、ArgSemSAT等算法进行对比。结果表明,求解相同数量的优先扩充,算法耗时较少,时间、空间复杂度有所降低。     

Encoding deductive argumentation in quantified Boolean formulae

There are a number of frameworks for modelling argumentation in logic. They incorporate a formal representation of individual arguments and techniques for comparing conflicting arguments. A common assumption for logic-based argumentation is that an argument is a pair 〈Φ,α〉 where Φ is minimal subset of the knowledge-base such that Φ is consistent and Φ entails the claim α. Different logics provide different definitions for consistency and entailment and hence give us different options for argumentation. Classical propositional logic is an appealing option for argumentation but the computational viability of generating an argument is an issue. To better explore this issue, we use quantified Boolean formulae to characterise an approach to argumentation based on classical logic.     

TOWARD A COMPUTATIONAL ANALYSIS OF PROBABILISTIC ARGUMENTATION FRAMEWORKS

In this article we analyze probabilistic argumentation frameworks (PAFs), defined as an extension of Dung abstract argumentation frameworks in which each argument n is asserted with a probability p_n. The debate around PAFs has so far centered on their theoretical definition and basic properties. This work contributes to their computational analysis by proposing a first recursive algorithm to compute the probability of acceptance of each argument under grounded and preferred semantics and by studying the behavior of PAFs with respect to reinstatement, cycles, and changes in argument structure. The computational tools proposed may provide strategic information for agents selecting the next step in an open argumentation process and they represent a contribution in the debate about gradualism in abstract argumentation.     

Modelling defeasible and prioritized support in bipolar argumentation

Cayrol and Lagasquie-Schiex introduce bipolar argumentation frameworks by introducing a second relation on the arguments for representing the support among them. The main drawback of their approach is that they cannot encode defeasible support, for instance they cannot model an attack towards a support relation. In this paper, we introduce a way to model defeasible support in bipolar argumentation frameworks. We use the methodology of meta-argumentation in which Dung??s theory is used to reason about itself. Dung??s well-known admissibility semantics can be used on this meta-argumentation framework to compute the acceptable arguments, and all properties of Dung??s classical theory are preserved. Moreover, we show how different contexts can lead to the alternative strengthening of the support relation over the attack relation, and converse. Finally, we present two applications of our methodology for modeling support, the case of arguments provided with an internal structure and the case of abstract dialectical frameworks.     

A labelling framework for probabilistic argumentation

The combination of argumentation and probability paves the way to new accounts of qualitative and quantitative uncertainty, thereby offering new theoretical and applicative opportunities. Due to a variety of interests, probabilistic argumentation is approached in the literature with different frameworks, pertaining to structured and abstract argumentation, and with respect to diverse types of uncertainty, in particular the uncertainty on the credibility of the premises, the uncertainty about which arguments to consider, and the uncertainty on the acceptance status of arguments or statements. Towards a general framework for probabilistic argumentation, we investigate a labelling-oriented framework encompassing a basic setting for rule-based argumentation and its (semi-) abstract account, along with diverse types of uncertainty. Our framework provides a systematic treatment of various kinds of uncertainty and of their relationships and allows us to back or question assertions from the literature.     

Incorporating rhetorical and plausible reasoning in a system for simulating argumentation

The article introduces argumentation theory, some examples of computational models of argumentation, some application examples, considers the significance and problems of argumentation systems, and outlines the significance and difficulties of the field. Also, the article describes a system which used rhetorical reasoning rules such as fairness, reciprocity, and deterrence which was used to simulate the text of a debate. The text was modelled using modern argumentation theory, and this model was used to build the system. The article discusses the system with regard to several aspects: its ability to deal with meaningful contradiction such as claim X supporting claim Y, yet claim Y attacking claim X; recursive arguments; inconsistency maintenance; expressiveness; encapsulation, the use of definitions as the basis for rules, and making generalisations using taxonomies. The article concludes with a discussion of domain dependence, rule plausibility, and some comparisons with formal logic.