Logical models of argument formalize commonsense reasoning while taking process and computation seriously. This survey discusses the main ideas which characterize different logical models of argument. It presents the formal features of a few main approaches to the modeling of argumentation. We trace the

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Argumentation theory has become an important topic in the field of AI. The basic idea is to construct arguments in favor and against a statement, to select the “acceptable” ones and, finally, to determine whether the original statement can be accepted or not. Several argumentation systems have been proposed in the literature. Some of them, the so-called rule-based systems, use a particular logical language with strict and defeasible rules. While these systems are useful in different domains (e.g. legal reasoning), they unfortunately lead to very unintuitive results, as is discussed in this paper. In order to avoid such anomalies, in this paper we are interested in defining principles, called rationality postulates, that can be used to judge the quality of a rule-based argumentation system. In particular, we define two important rationality postulates that should be satisfied: the consistency and the closure of the results returned by that system. We then provide a relatively easy way in which these rationality postulates can be warranted for a particular rule-based argumentation system developed within a

This article carries out a formal study of dialogue games for argumentation. A formal framework for such games is proposed which imposes an explicit reply structure on dialogues, where each dialogue move either attacks or surrenders to some earlier move of the other participant. The framework is flexible in several respects. It allows for different underlying logics, alternative sets of locutions and more or less strict rules for when they are allowed. In particular, it allows for varying degrees of coherence and flexibility when it comes to maintaining focus of a dialogue. Its formal nature supports the study of formal properties of specific dialogue protocols, especially on how they respect the underlying logic.

Negotiation is essential in settings where autonomous agents have conflicting interests and a desire to cooperate. For this reason, mechanisms in which agents exchange potential agreements according to various rules of interaction have become very popular in recent years as evident, for example, in the auction and mechanism design community. However, a growing body of research is now emerging which points out limitations in such mechanisms and advocates the idea that agents can increase the likelihood and quality of an agreement by exchanging arguments which influence each others ’ states. This community further argues that argument exchange is sometimes essential when various assumptions about agent rationality cannot be satisfied. To this end, in this article, we identify the main research motivations and ambitions behind work in the field. We then provide a conceptual framework through which we outline the core elements and features required by agents engaged in argumentation-based negotiation, as well as the environment that hosts these agents. For each of these elements, we survey and evaluate existing proposed techniques in the literature and highlight the major challenges that need to be addressed if argument-based negotiation research is to reach its full potential.

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Dung’s theory of abstract argumentation frameworks [8] led to the formalization of various argument-based semantics, which are actually particular forms of dealing with the issue of reinstatement. In this paper, we re-examine the issue of semantics from the perspective of postulates. In particular, we ask ourselves the question of which (minimal) requirements have to be fulfilled by any principle for handling reinstatement, and how this relates to Dung’s standard semantics. Our purpose is to shed new light on the ongoing discussion on which semantics is most appropriate.

This paper relates the Defeasible Logic Programming (DeLP ) framework and its semantics SEM DeLP to classical logic programming frameworks. In DeLP we distinguish between two different sorts of rules: strict and defeasible rules. Negative literals (A) in these rules are considered to represent classical negation. In contrast to this, in normal logic programming (NLP ), there is only one kind of rules, but the meaning of negative literals (notA) is different: they represent a kind of negation as failure, and thereby introduce defeasibility. Various semantics have been defined for NLP, notably the well-founded semantics WFS and the stable semantics Stable. In this paper we consider the transformation properties for NLP introduced by Brass and Dix and suitably adjusted for the DeLP framework. We show which transformation properties are satisfied, thereby identifying aspects in which NLP and DeLP differ. We contend that the transformation rules presented in this paper can he...

We present a formal model of argumentation based on situation calculus which captures both the logical and the procedural aspects of argumentation processes. The logic is used to determine what is accepted by each agent participating in the discussion and by the group as a whole, on the basis of the speech acts performed during argumentation. Argumentation protocols, also called rules of order, describe declaratively which speech acts are legal in a particular state of the argumentation. We first discuss argumentation with fixed rules of order. Our model tolerates protocol violations but makes it possible to object to illegal actions. In realistic settings the rules of order themselves can at any time become the topic of the debate. We show how meta level argumentation of this kind can be modelled in what we call dynamic argument systems. To illustrate the notions introduced in the paper we present a reconstruction of Rescher's theory of formal disputation and a dynamic argument system with three levels which we use to discuss a murder case. 1