Local Logics, Non-Monotonicity and Defeasible Argumentation

In this paper we present an embedding of abstract argumentation systems into the framework of Barwise and Seligman’s logic of information flow. We show that, taking P.M. Dung’s characterization of argument systems, a local logic over states of a deliberation may be constructed. In this structure, the key feature of non-monotonicity of commonsense reasoning obtains as the transition from one local logic to another, due to a change in certain background conditions. Each of Dung’s extensions of argument systems leads to a corresponding ordering of background conditions. The relations among extensions becomes a relation among partial orderings of background conditions. This introduces a conceptual innovation in Barwise and Seligman’s representation of commonsense reasoning.     

Temporal Defeasible Reasoning

An argumentation system that allows temporal reasoning using the notions of instant and interval is presented. Previous proposals just considered either instants or intervals. A many-sorted logic is used to represent temporal knowledge at the monotonic level. The logic considers how to formalize knowledge about explicit temporal references, events, properties and actions. The argumentation system provides a non-monotonic layer in which to reason about the justification of truths in the system. The proposal is illustrated showing how to solve well-known problems of the literature. Received 21 June 2000 / Revised 7 December 2000 / Accepted in revised form 8 January 2001     

Defeasible reasoning and logic programming

The general conditions of epistemic defeat are naturally represented through the interplay of two distinct kinds of entailment, deductive and defeasible. Many of the current approaches to modeling defeasible reasoning seek to define defeasible entailment via model-theoretic notions like truth and satisfiability, which, I argue, fails to capture this fundamental distinction between truthpreserving and justification-preserving entailments. I present an alternative account of defeasible entailment and show how logic programming offers a paradigm in which the distinction can be captured, allowing for the modeling of a larger range of types of defeat. This is possible through a natural extension of the declarative and procedural semantics of Horn clauses.     

纤维逻辑

形式逻辑已经从简单命题逻辑发展到比较复杂的模态逻辑系列。但是在主体环境下,已有逻辑的复杂性仍然不能有效刻画主体复杂的心智。有一些人工智能研究者根据主体心智的多重性,在模态逻辑中引入多种模态算子,并借此对主体加以刻画。但是原来的可能世界语义却难以容纳如此复杂的语法,出现了很多不合理的地方。本文首先介绍了新近出现的纤维逻辑（fibring logics）,然后归纳了目前将此理论应用在主体BDI建模的研究现状,最后分析纤维逻辑的不足之处,讨论了其他可能的应用,并对今后的工作做了展望。     

Defeasible inheritance with doubt index and its axiomatic characterization

This article introduces and uses a representation of defeasible inheritance networks where links in the network are viewed as propositions, and where defeasible links are tagged with a quantitative indication of the proportion of exceptions, called the doubt index. This doubt index is used for restricting the length of the chains of inference.The representation also introduces the use of defeater literals that disable the chaining of subsumption links. The use of defeater literals replaces the use of negative defeasible inheritance links, expressing “most A are not B”. The new representation improves the expressivity significantly.Inference in inheritance networks is defined by a combination of axioms that constrain the contents of network extensions, a heuristic restriction that also has that effect, and a nonmonotonic operation of minimizing the set of defeater literals while retaining consistency.We introduce an underlying semantics that defines the meaning of literals in a network, and prove that the axioms are sound with respect to this semantics. We also discuss the conditions for obtaining completeness.Traditional concepts, assumptions and issues in research on nonmonotonic or defeasible inheritance are reviewed in the perspective of this approach.     

一种研讨模型

提出了一种研讨模型.该模型用简化的Toulmin模型表示争议内部结构,用Dung的抽象辩论框架的方法定义争议之间的关系,给出了争议可防卫性和陈述可接受性算法.用该模型对已有文献中的实例重新建模,结果表明,该模型能够准确计算陈述可接受性并得出研讨结果.该模型研究出发点是对实际群体研讨建模,但也可以用于非经典逻辑形式系统建模.     

战争设计工程专家群体研讨模型*

针对战争设计工程中专家群体研讨问题,根据研讨的主题以及目标,将专家群体研讨划分为三类:寻求信息研讨、质询研讨和商议研讨。在研讨类型划分的基础上,建立了战争设计工程群体专家研讨模型。该模型主要用于对战争设计工程中专家群体研讨过程建模,有利于专家对研讨进程的了解。最后阐述了该模型在战争设计工程中的应用。     

Knowledge and information distribution leveraged by intelligent agents

Knowledge and Information distribution is indeed one of the main processes in Knowledge Management. Today, most Information Technology tools for supporting this distribution are based on repositories accessed through Web-based systems. This approach has, however, many practical limitations, mainly due to the strain they put on the user, who is responsible of accessing the right Knowledge and Information at the right moments. As a solution for this problem, we have proposed an alternative approach which is based on the notion of delegation of distribution tasks to synthetic agents, which become responsible of taking care of the organization's as well as the individuals' interests. In this way, many Knowledge and Information distribution tasks can be performed on the background, and the agents can recognize relevant events as triggers for distributing the right information to the right users at the right time.In this paper, we present the JITIK approach to model knowledge and information distribution, giving a high-level account of the research made around this project, emphasizing two particular aspects: a sophisticated argument-based mechanism for deciding among conflicting distribution policies, and the embedding of JITIK agents in enterprises using the service-oriented architecture paradigm. It must be remarked that a JITIK-based application is currently being implemented for one of the leading industries in Mexico.     

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.     

Proof Theory for Casari's Comparative Logics

Comparative logics were introduced by Casari in the 1980s totreat aspects of comparative reasoning occurring in naturallanguage. In this article Gentzen systems are defined for theselogics by means of a special mix rule that combines calculifor various substructural logics with a hypersequent calculusfor Meyer and Slaney's Abelian logic. Cut-elimination is establishedfor all these systems, and as a consequence, a positive answeris given to an open problem on the decidability of the basiccomparative logic.     

Optimality Theory as a Family of Cumulative Logics

We investigate two formalizations of Optimality Theory, a successful paradigm in linguistics.We first give an order-theoretic counterpart for the data and processinvolved in candidate evaluation.Basically, we represent each constraint as a function that assigns every candidate a degree of violation.As for the second formalization, we define (after Samek-Lodovici and Prince) constraints as operations that select the best candidates out of a set of candidates.We prove that these two formalizations are equivalent (accordingly, there is no loss of generality with using violation marks and dispensing with them is only apparent).Importantly, we show that the second formalization is equivalent with a class of operations over sets of formulas in a given logical language.As a result, we prove that Optimality Theory can be characterized by certain cumulative logics.So, applying Optimality Theory is shown to be reasoning by the rules of cumulative logics.     

一种渐进式论辩语义的论证博弈模型

在可计算论辩模型中,论辩语义的证明理论解决如何判定给定论辩语义中某个论证的证成状态的问题,这通常需要建构与之对应的论证博弈模型。论证博弈发生在正方和反方的论证交互过程中,正反双方都是通过给出攻击论证来质疑对方的论证和辩护己方的论证,正方只有在论证博弈中获胜才能使其初始论证获得确定的证成状态。文中定义了一种被称为BRD-论辩语义的渐进式论辩语义,不同于Dung的抽象论辩语义,它是在结构化论辩框架ASPIC+中嵌入了一种用于计算论证的强度和证成度的循环语义。为了给出该语义的证明理论,建构了与之对应的论证博弈模型。     

A Framework for Automated Reasoning in Multiple-Valued Logics

The language of signed formulas offers a first-order classical logic framework for automated reasoning in multiple-valued logics. It is sufficiently general to include both annotated logics and fuzzy operator logics. Signed resolution unifies the two inference rules of annotated logics, thus enabling the development of an SLD-style proof procedure for annotated logic programs. Signed resolution also captures fuzzy resolution. The logic of signed formulas offers a means of adapting most classical inference techniques to multiple-valued logics.     

Argument-based mixed recommenders and their application to movie suggestion

Recommender systems have become prevalent in recent years as they help users to access relevant items from the vast universe of possibilities available these days. Most existing research in this area is based purely on quantitative aspects such as indices of popularity or measures of similarity between items or users. This work introduces a novel perspective on movie recommendation that combines a basic quantitative method with a qualitative approach, resulting in a family of mixed character recommender systems. The proposed framework incorporates the use of arguments in favor or against recommendations to determine if a suggestion should be presented or not to a user. In order to accomplish this, Defeasible Logic Programming (DeLP) is adopted as the underlying formalism to model facts and rules about the recommendation domain and to compute the argumentation process. This approach has a number features that could be proven useful in recommendation settings. In particular, recommendations can account for several different aspects (e.g., the cast, the genre or the rating of a movie), considering them all together through a dialectical analysis. Moreover, the approach can stem for both content-based or collaborative filtering techniques, or mix them in any arbitrary way. Most importantly, explanations supporting each recommendation can be provided in a way that can be easily understood by the user, by means of the computed arguments. In this work the proposed approach is evaluated obtaining very positive results. This suggests a great opportunity to exploit the benefits of transparent explanations and justifications in recommendations, sometimes unrealized by quantitative methods.     

Defeasible Reasoning in Japanese Criminal Jurisprudence

Modeling legal argumentation is one of the most important research in AI and Law, and a lot of models have been proposed. However, most research has not treated value judgement and debate. In this paper, we introduce a legal reasoning model which covers various aspects of legalreasoning such as making argument, selecting argument and debate.Furthermore, we present how criminal law is described and reasoned inthis model.     

分级论辩系统的逻辑研究

近年来,形式论证已逐渐成为人工智能领域的研究热点之一。自Dung于1995年提出抽象辩论框架起,学术界普遍认为论辩的核心任务是在各种基于外延的语义下对论点集进行评估,以确定其辩护状态。分级论辩系统(Graded Argumentation System,GAS)是对经典Dung型论辩系统(Dung-style Argumentation System,DAS)的推广,通过一般化DAS语义的两个核心性质,即无冲突性和可接受性,来提供更细化的论点状态概念。当前的论辩系统语义等效性研究主要集中在框架和论点层次上,可为其结构约简提供有力的保证。针对两个不同分级论辩系统中论点的语义等效问题,首先运用分级模态逻辑(Graded Modal Logic,GML)形式化分级论辩系统的片段,然后建立并证明了分级论辩系统基于外延的语义和GML公式之间的一一对应关系,最后定义分级互模拟关系并证明其蕴含分级论辩系统的4个重要的语义等价性。     

Defeasible Inheritance Through Specialization

Typed substitution provides a means of capturing inheritance in logic deduction systems. However, in the presence of method overriding and multiple inheritance, inheritance is known to be nonmonotonic, and the semantics of programs becomes a problematic issue. This article attempts to provide a general framework, based on Dung's argumentation theoretic framework, for developing a natural semantics for programs with dynamic nonmonotonic inheritance. The relationship between the presented semantics and perfect‐model (with overriding) semantics, proposed by Dobbie and Topor (1995), is investigated. It is shown that for inheritance‐stratified programs, the two semantics coincide. However, the proposed semantics also provides correct skeptical meanings for the programs that are not inheritance‐stratified.