35 research outputs found
A Comparative Study of Ranking-based Semantics for Abstract Argumentation
Argumentation is a process of evaluating and comparing a set of arguments. A
way to compare them consists in using a ranking-based semantics which
rank-order arguments from the most to the least acceptable ones. Recently, a
number of such semantics have been proposed independently, often associated
with some desirable properties. However, there is no comparative study which
takes a broader perspective. This is what we propose in this work. We provide a
general comparison of all these semantics with respect to the proposed
properties. That allows to underline the differences of behavior between the
existing semantics.Comment: Proceedings of the 30th AAAI Conference on Artificial Intelligence
(AAAI-2016), Feb 2016, Phoenix, United State
Modélisation des interactions entre agents rationnels : les jeux booléens
Boolean games are a logical setting for representing static games in a succinct way, taking advantage of the expressive power and conciseness of propositional logic. Boolean games allow to express compactly two-players zero-sum static games with binary preferences: an agent's strategy consists of a truth assignment of the propositional variables she controls, and a player's preferences are expressed by a plain propositional formula.These three restrictions (two-players, zero-sum, binary preferences) strongly limit the expressivity of the framework. The first two can be easily encompassed by defining the agents' preferences as an arbitrary n-uple of propositional formulas. Two others notions have been studied: dependencies between players (if the goal, and hence the satisfaction, of a player i depends on some variables controlled by a player j, then i may need some action of j to see her goal satisfied) and efficient coalitions (a coalition in a Boolean game is efficient if it has the power to guarantee that all goals of the members of the coalition are satisfied). We give simple characterizations of Nash equilibria and dominated strategies, and investigate the computational complexity of the related problems.Then, we relax the last restriction by coupling Boolean games with propositional languages for compact preference representation; we consider generalized Boolean games where players' preferences are expressed within the two following languages: propositionalized CP-nets, and then prioritized goals.Les jeux boolĂ©ens permettent de reprĂ©senter les jeux stratĂ©giques d'une maniĂšre succincte en tirant profit du pouvoir d'expression et de la concision de la logique propositionnelle. Informellement, un jeu boolĂ©en est un jeu Ă deux joueurs, chacun d'entre eux contrĂŽlant un ensemble de variables propositionnelles, et Ă somme nulle. La fonction d'utilitĂ© du joueur 1 (et donc celle du joueur 2 qui est son opposĂ©) est reprĂ©sentĂ©e par une formule de la logique propositionnelle, appelĂ©e forme boolĂ©enne du jeu. Ainsi, un joueur dans un jeu boolĂ©en a des prĂ©fĂ©rences dichotomiques : son but est satisfait ou ne l'est pas.Ces trois restrictions (deux joueurs, somme nulle, prĂ©fĂ©rences binaires) limitent fortement l'expressivitĂ© de ce cadre. Les deux premiĂšres restrictions peuvent ĂȘtre facilement rĂ©solues en dĂ©finissant les prĂ©fĂ©rences des agents comme Ă©tant un n-uplet de formules propositionnelles (une pour chaque agent). Des outils simples issus de la logique propositionnelle nous permettent ainsi de caractĂ©riser certaines propriĂ©tĂ©s du jeu. Deux autres notions ont alors Ă©tĂ© Ă©tudiĂ©es : la dĂ©pendance entre joueurs (si le but (et donc la satisfaction) d'un joueur i dĂ©pend de variables contrĂŽlĂ©es par le joueur j, alors i aura besoin de j pour satisfaire son but) et les coalitions de joueurs (une coalition dans un jeu boolĂ©en est efficace si elle peut garantir Ă tous ses membres que leurs buts sont satisfaits). Dans les deux cas, l'objectif est de faciliter le calcul des concepts de solution tels que les Ă©quilibres de Nash en stratĂ©gies pures.Lever la troisiĂšme restriction consiste Ă exprimer des prĂ©fĂ©rences (non binaires) dans un cadre propositionnel. Cela est possible en utilisant un langage de reprĂ©sentation compacte de prĂ©fĂ©rences. Nous avons integrĂ© ici deux de ces langages aux jeux boolĂ©ens : tout d'abord, les buts Ă prioritĂ© puis les CP-nets
Coalitional games for abstract argumentation
International audienceIn this work we address the issue of the uncertainty faced by a user participating in multiagent debate. We propose a way to compute the relative relevance of arguments for such a user, by merging the classical argumentation framework proposed in [5] into a game theoretic coalitional setting, where the worth of a collection of arguments (opinions) can be seen as the combination of the information concerning the defeat relation and the preferences over arguments of a " user ". Via a property-driven approach, we show that the Shapley value [15] for coalitional games defined over an argumentation framework, can be applied to resume all the information about the worth of opinions into an attribution of relevance for the single arguments. We also prove that, for a large family of (coalitional) argumentation frameworks, the Shapley value can be easily computed
Argumentation Ranking Semantics based on Propagation
International audienceArgumentation is based on the exchange and the evaluation of interacting arguments. Unlike Dung's theory where arguments are either accepted or rejected, ranking-based semantics rank-order arguments from the most to the least acceptable ones. We propose in this work six new ranking-based semantics. We argue that, contrarily to existing ranking semantics in the literature, that focus on evaluating attacks and defenses only, it is reasonable to give a prominent role to non-attacked arguments, as it is the case in standard Dung's semantics. Our six semantics are based on the propagation of the weight of each argument to its neighbors, where the weight of non-attacked arguments is greater than the attacked ones
A Parametrized Ranking-based Semantics for Persuasion
International audienceIn this paper we question the ability of the existant ranking semantics for argumentation to capture persuasion settings, emphasizing in particular the phenomena of protocatalepsis (the fact that it is often efficient to anticipate the counter-arguments of the audience), and of fading (the fact that long lines of argumentation become ineffective). It turns out that some widely accepted principles of ranking-based semantics are incompatible with a faithful treatment of these phenomena. We thus propose a parametrized semantics based on propagation of values, which allows to control the scope of arguments to be considered for evaluation. We investigate its properties (identifying in particular threshold values guaranteeing that some properties hold), and report experimental results showing that the family of rankings that may be returned have a high coherence rate
Coalitions efficaces dans les jeux booléens (RFIA 2008)
National audienceBoolean games are a logical setting for representing stra-tegic games in a succinct way, taking advantage of the ex-pressive power and conciseness of propositional logic. A Boolean game consists of a set of players, each of which controls a set of propositional variables and has a speciïŹc goal expressed by a propositional formula. We show here that Boolean games are a very simple setting, yet sophisti-cated enough, for studying coalitions. Due to the fact that players have dichotomous preferences, the following no-tion emerges naturally : a coalition in a Boolean game is efïŹcient if it has the power to guarantee that all goals of the members of the coalition are satisïŹed. We study the proper-ties of efïŹcient coalitions.Les jeux boolĂ©ens permettent de reprĂ©senter succinctement des jeux en tirant profit du pouvoir dâexpression et de la concision de la logique propositionnelle. Un jeu boolĂ©en est constituĂ© dâun ensemble de joueurs, chacun dâentre eux contrĂŽlant un ensemble de variables propositionnelles et ayant un but reprĂ©sentĂ© par une formule en logique propositionnelle. Nous montrons ici que les jeux boolĂ©ens sont un cadre trĂšs simple, et pourtant assez sophistiquĂ©, pour Ă©tudier les coalitions. Ătant donnĂ© que les joueurs ont des prĂ©fĂ©rences dichotomiques, la notion suivante Ă©merge naturellement: une coalition dans un jeu boolĂ©en est efficace si elle peut garantir Ă tous ses membres que leurs buts sont satisfaits. Nous Ă©tudions ici les propriĂ©tĂ©s de ces coalitions
Translation of an argumentation framework into a CP-boolean game (ICTAI 2009)
International audienceThere already exist some links between argumentation and game theory. For instance, dynamic games can be used for simulating interactions between agents in an argumentation process. In this paper, we establish a new link between these domains in a static framework: we show how an argumentation framework can be translated into a CP-Boolean game and how this translation can be used for computing extensions of argumentation semantics. We give formal algorithms to do so
Argumentation et CP-jeux booléens
National audienceDes liens entre argumentation et thĂ©orie des jeux existent dĂ©jĂ . Par exemple, les jeux dynamiques permettent de simuler les interactions entre agents dans un processus dâargumentation. Dans ce papier, nous Ă©tablissons un nouveau lien entre ces domaines dans un cadre statique : nous montrons comment un CP-jeu boolĂ©en peut ĂȘtre utilisĂ© pour calculer des extensions en argumentation, et donnons des algorithmes formels pour le faire
Compact Preference Representation for Boolean Games
International audienc