Semantic Change and Extension Enforcement in Abstract Argumentation

Change in argumentation frameworks has been widely studied in the recent years. Most of the existing works on this topic are concerned with change of the structure of the argumentation graph (addition or removal of arguments and attacks), or change of the outcome of the framework (acceptance statuses of arguments). Change on the acceptability semantics that is used in the framework has not received much attention so far. Such a change can be motivated by different reasons, especially it is a way to change the outcome of the framework. In this paper, it is shown how semantic change can be used as a way to reach a goal about acceptance statuses in a situation of extension enforcement

Quelques réflexions autour de la notion de bêtise artificielle

"La bêtise est souvent l'ornement de la beauté ; c'est elle qui donne aux yeux cette limpidité morne des étangs noirâtres et ce calme huileux des heures tropicales." Charles Baudelaire, Journaux intimes (1887)National audienceProfessor Rollin wrote about artificial stupidity. Could we remain indifferent to this ? This article shows the contrary.Le professeur Rollin a écrit au sujet de la bêtise artificielle. Pouvions-nous rester indifférent à cela ? Cet article montre le contraire

Dynamique des systèmes d'argumentation

This thesis tackles the problem of integrating a new piece of information in an abstract argumenta- tion framework. Such a framework is a directed graph such that its nodes represent the arguments, and the directed edges represent the attacks between arguments. There are different ways to decide which arguments are accepted by the agent who uses such a framework to represent her beliefs.An agent may be confronted with a piece of information such that "this argument should be accepted", which is in contradiction with her current beliefs, represented by her argumentation framework.In this thesis, we have studied several approaches to incorporate a piece of information in an argumenta- tion framework.Our first contribution is an adaptation of the AGM framework for belief revision, which has been de- veloped for characterizing the incorporation of a new piece of information when the agent’s beliefs are represented in a logical setting. We have adapted the rationality postulates from the AGM framework to characterize the revision operators suited to argumentation frameworks, and we have identified several ways to generate the argumentation frameworks resulting from the revision.We have also shown how to use AGM revision as a tool for revising argumentation frameworks. Our approach uses a logical encoding of the argumentation framework to take advantage of the classical re- vision operators, for deriving the expected result.At last, we have studied the problem of enforcing a set of arguments (how to change an argumentation framework so that a given set of arguments becomes an extension). We have developed a new family of operators which guarantee the success of the enforcement process, contrary to the existing approaches, and we have shown that a translation of our approaches into satisfaction and optimization problems makes possible to develop efficient tools for computing the result of the enforcement.Cette thèse traite du problème de l’intégration d’une nouvelle information dans un système d’argumen- tation abstrait. Un tel système est un graphe orienté dont les nœuds représentent les arguments, et les arcs représentent les attaques entre arguments. Il existe divers moyen de décider quels arguments sont acceptés par l’agent qui utilise un tel système pour représenter ses croyances.Il peut arriver dans la vie d’un agent qu’il soit confronté à une information du type "tel argument devrait être accepté", alors que c’est en contradiction avec ses croyances actuelles, représentées par son système d’argumentation.Nous avons étudié dans cette thèse diverses approches pour intégrer une information à un système d’ar- gumentation.Notre première contribution est une adaptation du cadre AGM pour la révision de croyances, habituelle- ment utilisé lorsque les croyances de l’agent sont représentées dans un formalisme logique. Nous avons notamment adapté les postulats de rationalité proposés dans le cadre AGM pour pouvoir caractériser des opérateurs de révision de systèmes d’argumentation, et nous avons proposé différents moyens de générer les systèmes d’argumentation résultant de la révision.Nous avons ensuite proposé d’utiliser la révision AGM comme un outil pour réviser les systèmes d’ar- gumentation. Il s’agit cette fois-ci d’une approche par encodage en logique du système d’argumentation, qui permet d’utiliser les opérateurs de révision usuels pour obtenir le résultat souhaité.Enfin, nous avons étudié le problème du forçage d’un ensemble d’arguments (comment modifier le sys- tème pour qu’un ensemble donné soit une extension). Nous avons proposé une nouvelle famille d’opé- rateurs qui garantissent le succès de l’opération, contrairement aux opérateurs de forçage existants, et nous avons montré qu’une traduction de nos approches en problèmes de satisfaction ou d’optimisation booléenne permet de développer des outils efficaces pour calculer le résultat du forçage

Constraints and Changes in Argumentation: State of the Art and Challenges of Argumentation Dynamics

19th European Agent Systems Summer School (EASSS 2017), Gdańsk, PolandArgumentation dynamics has become a hot topic in recent years in the argumentation community, with several applications in the context of multi-agent systems: negotiation, persuasion between agents, online debate platforms, benefit from advances on this topic. Argumentation dynamics has in addition strong connections with well-established reasoning research areas, such as belief change. At a high level, argumentation dynamics consists in taking into account some constraint about an argumentation system (e.g. some attack must be added or some argument must be accepted) that an agent wants to enforce, and in modifying this argumentation system to make the constraint satisfied by it. In this tutorial, we review the existing approaches for argumentation dynamics. We classify them depending on the kind of constraint which is considered, and how the framework is modified to make the constraint satisfied. We show how this classification highlights open questions for future work about argumentation dynamics

Constraints and Changes: A Survey of Abstract Argumentation Dynamics

International audienceThis paper addresses the issue of the dynamic enforcement of a constraint in an argumentation system. The system consists in (1) an argumentation framework, made up, notably, of a set of arguments and of an attack relation, (2) an evaluation semantics, and (3) the evaluation result, computed from (1) and (2). An agent may want another agent to consider a new attack, or to have a given argument accepted, or even to relax the definition of the semantics. A constraint on any of the three components is thus defined, and it has to be enforced in the system. The enforcement may result in changes on components of the system. The paper surveys existing approaches for the dynamic enforcement of a constraint and its consequences, and reveals challenging enforcement cases that remain to be investigated

Quantifying the Difference between Argumentation Semantic

International audienceProperties of argumentation semantics have been widely studied in the last decades. However, there has been no investigation on the question of difference measures between semantics. Such measures turn helpful when the semantics associated to an argumentation framework may have to be changed, in a way that ensures that the new semantics is not too dissimilar from the old one. Three main notions of difference measures between semantics are defined in this paper. Some of these measures are shown to be distances or semi-distances

How Different Are Two Argumentation Semantics? (JIAF 2016)

International audiencetIn the last decades, many argumentation semanticshave been defined, and their properties studied. Somecomparison criteria between semantics have been high-lighted, but no measures of difference between seman-tics have been defined. Such measures turn helpful inthe case where the semantics associated to an argumen-tation framework may have to be changed, in a way thatensures that the new semantics is not too dissimilar fromthe old one. Three main notions of difference measuresbetween semantics are defined in this paper. Some ofthese measures are shown to be distances, semi-distancesor pseudo-distancesCes dernières années, de nombreuses sémantiques pour l’argumentation ont été définies, et leurs propriétés étudiées. Des critères de comparaison entre sémantiques ont été proposés, mais aucune mesure de différence entre sémantique n’a été définie. De telles mesures se révèlent utiles dans le cas où la sémantique associée`a un système d’argumentation doit être changée, d’une manière qui assure que la nouvelle sémantique n’est pas trop éloignée de l’ancienne. Trois principales mesures de différence sont proposées dans cet article. Nous montrons que certaines de ces mesures sont des distances,des semi-distances, ou des pseudo-distances