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

A reasoning platform based on the MI Shapley inconsistency value

International audienceIn this paper we show how to build a reasoning platform us- ing an inconsistency value. The idea is to use an inconsistency value for evaluating how much each formula of the belief base is responsible of the inconsistency of the base. Then this evaluation allows us to obtain a strati cation (total pre-order) of the base, that can be used as the preferential input for di erent reasoning tasks, such as inference, belief revision, or conciliation. We show that the obtained operators are interesting and have good logical properties. We use as inconsistency value, the MI Shapley inconsistency value, that is known to have good properties, and that can be computed from minimal inconsistent subsets. We developed a java-based platform, that use the Sat4j library for computing the minimal inconsistent subsets, and that allows to have an e ective way to compute the MI Shapley inconsistent subsets. We implemented also several inference, revision and conciliation methods, that use this inconsistency value. So this provides a complete reasoning platform, that can be used for instance for academic purposes

Propositional Merging and Judgment Aggregation: Two Compatible Approaches?

International audienceThere are two theories of aggregation of logical formu-lae: merging and judgment aggregation. In this work we investigate the relationships between these theories; one of our objectives is to point out some correspondences/discrepancies between the associated rationality properties

Planification multi-agent et diagnostic stratégique

Quand plusieurs agents opèrent dans un environnement commun, leurs plans peuvent interférer. Le résultat de chaque plan peut être altéré par cette interaction et la notion de plan valide de la planification classique (mono-agent) ne convient plus. Dans cet article, nous étendons ce cadre à un cadre multi-agent. Nous montrons comment les "meilleurs" plans pour un agent rationnel peuvent être caractérisés en utilisant des notions de théorie des jeux, en particulier celle d'équilibre de Nash. Nous identifions par ailleurs les scénarios pour lesquels une coopération entre agents devrait s'effectuer et montrons que nombre d'informations stratégiques peuvent être dérivées du jeu

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

Compositional Belief Merging

Abstract Belief merging aims at extracting a coherent and informative view from a set of belief bases. A first requirement for belief merging operators is to obey basic rationality conditions. Another expected property is to preserve as much information as possible from the input bases. In this paper, we show how new merging operators, called compositional operators, can be defined from existing ones. Such operators aim at offering a higher discriminative power than the merging operators on which they are based, without leading to a complexity shift or losing rationality postulates. We identify some sufficient conditions for ensuring that rationality is fully preserved by composition

Probing the spin dimensionality in single-layer CrSBr van der Waals heterostructures by magneto-transport measurements

Two-dimensional (2D) magnetic materials offer unprecedented opportunities both in terms of fundamental concepts and applied devices with special relevance in the fields of spintronics and magnonics. Beyond the pioneering studies on CrI3 and Cr2Ge2Te6, the family of 2D magnets has expanded to layered antiferromagnets with different spin anisotropies and spin textures. However, all these compounds are highly insulating, thus limiting their possibilities for being integrated into devices. Of particular interest is the case of the layered metamagnet CrSBr, a 2D semiconductor formed by ferromagnetic layers (Tc ~ 150 K) coupled antiferromagnetically between them. This material exhibits a rich physical scenario, including thermal spin dimensionality crossovers and low-temperature hidden order (T* ~ 40 K). Here, we inspect the magneto-transport properties of monolayer, bilayer and trilayer CrSBr integrated into vertical van der Waals heterostructures. Our results in the monolayer limit demonstrate (1) the marked low dimensional character of the ferromagnetic layer, with short-range correlations extending at temperatures well above Tc, (2) a spin anisotropy, with the spins spontaneously aligned along the easy axis (b) of the plane, (3) a reorientation of these spins along a and c upon applying a moderate magnetic field in these directions, and (4) the appearance of field-induced phases in these two directions below ca. 30-40 K due to a cooperative freezing of the spins. In the multilayer case, a spin valve-like behavior is also observed characterized by a negative MR strongly enhanced below T*. Overall, the present results, supported by first-principles calculations, show that the monolayer and bilayer of CrSBr capture most of the physics present in the bulk, offering new insights into the physics of 2D magnets and the integration of these layers into vertical spintronic devices.Comment: 4 figure

SBGM : Conciliation et mesures de conflits

Nous proposons la définition de nouveaux opérateurs de conciliation. Ces opérateurs sont basés sur un processus itératif de sélection/affaiblissement des croyances/buts des agents, jusqu'à trouver un consensus (accord) entre les agents. Pour définir un opérateur particulier, il faut donc choisir la fonction de sélection et la fonction d'affaiblissement. Dans les travaux précédents la fonction de sélection était définie arbitrairement. Nous proposons de prendre comme fonction de sélection une mesure de conflit basée sur la valeur de Shapley, qui permet de défi- nir la part de conflit imputable à chaque agent. Cela mène à une formalisation plus intuitive de ces processus de négociation abstraits. We propose to define new conciliation operators. Those operators are based on an iterative selection/ weakening process of the beliefs/goals of the agents, until a consensus (agreement) is found between the agents. To define a particular operator, it just need to choose a choice function and a weakening function. In previous works the choice function was defined arbitrarily. We propose to take as choice function a measure of conflict based on the Shapley value, that allows to define the quantity of conflict due to each agent. This leads to a more intuitive formalization of those abstract negotiation processes

More games in belief game model: a preliminary report

International audienc