Papers by patricia everaere
Le Centre pour la Communication Scientifique Directe - HAL - Diderot, May 4, 2015
The problem of aggregating pieces of propositional information coming from several agents has giv... more The problem of aggregating pieces of propositional information coming from several agents has given rise to an intense research activity. Two distinct theories have emerged. On the one hand, belief merging has been considered in AI as an extension of belief revision. On the other hand, judgment aggregation has been developed in political philosophy and social choice theory. Judgment aggregation focusses on some specific issues (represented as formulas and gathered into an agenda) on which each agent has a judgment, and aims at defining a collective judgment set (or a set of collective judgment sets). Belief merging considers each source of information (the belief base of each agent) as a whole, and aims at defining the beliefs of the group without considering an agenda. In this work the relationships between the two theories are investigated both in the general case and in the fully informed case when the agenda is complete (i.e. it contains all the possible interpretations). Though it cannot be ensured in the general case that the collective judgment computed using a rational belief merging operator is compatible with the collective judgment computed using a rational judgment aggregation operator, we show that some close correspondences between the rationality properties considered in the two theories exist when the agenda is complete.
Approches de la révision et de la fusion d'informations
National audienceCh.11: Approches de la révision et de la fusion d’informations - 11.1 Introducti... more National audienceCh.11: Approches de la révision et de la fusion d’informations - 11.1 Introduction - 11.2 Révision de croyances en logique - 11.3 Révision itérée - 11.4 Approche logique de la fusion d’informations - 11.5 Approches - valuées de la révision et de la fusion - 11.6 Conclusio
Journal of Artificial Intelligence Research, 2007
Merging operators aim at defining the beliefs/goals of a group of agents from the beliefs/goals o... more Merging operators aim at defining the beliefs/goals of a group of agents from the beliefs/goals of each member of the group. Whenever an agent of the group has preferences over the possible results of the merging process (i.e., the possible merged bases), she can try to rig the merging process by lying on her true beliefs/goals if this leads to better merged base according to her point of view. Obviously, strategy-proof operators are highly desirable in order to guarantee equity among agents even when some of them are not sincere. In this paper, we draw the strategy-proof landscape for many merging operators from the literature, including model-based ones and formula-based ones. Both the general case and several restrictions on the merging process are considered.
Revue d'intelligence artificielle, 2011
Allouer m ressources entre n agents, de façon à optimiser leur bien-être, est un problème qui peu... more Allouer m ressources entre n agents, de façon à optimiser leur bien-être, est un problème qui peut souvent être résolu de manière centralisée. Cependant, pour certaines fonctions de bien-être social, une résolution centralisée n'est pas envisageable. Par exemple, le bien-être de Nash est une fonction qui a d'indéniables qualités mais qui ne peut être optimisée de manière classique. De plus, de nombreuses applications reposent sur des hypothèses qui ne peuvent pas être prises en compte par ces techniques centralisées alors que d'autres méthodes le permettent, comme les approches multi-agents. Après une présentation du problème multi-agents d'allocation de ressources, nous mettons en évidence les difficultés liées aux techniques centralisées et distribuées existantes. Nous proposons une méthode s'appuyant sur la notion de transaction sociale que nous revendiquons être la seule méthode « anytime » capable de résoudre efficacement le problème d'allocation de Nash. ABSTRACT. Solving the allocation of m resources between n agents is a problem which has been mainly studied in a centralized way. However, some welfare functions cannot be addressed by such approaches. The Nash welfare, which has interesting qualities cannot be solved in such a way. Moreover, many real problems rely on aspects that cannot be handled by centralized techniques whereas multiagent methods are efficient. After having presented the multiagent allocation problem, we show the difficulties of centralized and distributed approaches. We propose a solving method based on social transactions and we claim that our anytime solving method is the only one able to effectively address this problem of obvious practical interests.
International Journal of Parallel, Emergent and Distributed Systems, 2009
The volume of E-commerce transactions has considerably increased in the last several years. One o... more The volume of E-commerce transactions has considerably increased in the last several years. One of the most important aspects of such progress is the efforts made to develop and deploy dependable and secure payment infrastructures. Among these infrastructures is electronic cash, which is an attempt to reproduce the characteristics of paper cash in online transactions. Electronic cash schemes have so far been the purpose of a significant amount of research work. Although real-life deployments of such schemes are expected to take place in highly distributed environments, limited attention has been paid in the literature on underlying architectural issues. So far the focus has mostly been on addressing only security issues. However, for real-life deployment, distributed processing criteria such as performance, scalability, and availability are of prime importance. In this paper, through a survey of the literature, we identify and analyze the different distributed architectural styles underlying existing e-cash schemes. We discuss the strengths and limitations of these architectures with respect to fundamental system distribution criteria. In light of such discussion, we make some recommendations for designing effective distributed e-cash systems from an architectural perspective.
Je voudrais remercier mes deux directeurs de thèse, Pierre Marquis et Sébastien Konieczny. Les re... more Je voudrais remercier mes deux directeurs de thèse, Pierre Marquis et Sébastien Konieczny. Les remercier pour la confiance qu'ils m'ont accordée en acceptant de me suivre au cours de ces trois années, mais surtout pour les qualités humaines et scientifiques dont ils font preuve. Je pense avoir eu beaucoup de chance d'être entourée par deux personnes aussi intelligentes, intéressantes, disponibles et honnêtes. Grâce à eux, j'ai beaucoup appris durant ces trois années, sur le plan scientifique, bien sûr, mais aussi sur le plan personnel. Cette aventure m'a permis de découvrir le monde de la recherche et de relever un défi. Et finalement, c'est de cela dont je suis la plus fière, et c'est aussi pour cela que je voudrais les remercier. Je voudrais également remercier les rapporteurs, Jérôme Lang et Torsten Schaub, d'avoir accepté de me sacrifier une partie de leur temps si précieux, et de leurs remarques pertinentes et utiles. Merci également aux membres du jury, Éric Grégoire, Salem Benferhat, Isabelle Bloch et Anthony Hunter pour leur présence à la soutenance, et d'avoir si spontanément accepté cette responsabilité. Je voudrais également remercier l'Université d'Artois et l'Université de Lille I de m'avoir permis de progresser plus rapidement dans mes recherches en m'accordant une décharge de service. Je profite de cette occasion pour saluer mes anciens collègues de l'IUT de Lens, département informatique, où j'ai rencontré des gens très attachants. Ce sont eux en premier qui m'ont donné envie de me lancer ce défi, et qui ont eu confiance en mes capacités. En particulier, merci à Assef, Sylvie, Olivier et Gilles pour leur aide lors de mes premiers pas en latex, leurs encouragements et leur amitié. Merci à Bertrand, Daniel, Sylvain et Jean-Luc pour leur aide, et merci à tout ceux que je ne cite pas... Enfin, un grand merci à Alain pour son soutien inconditionnel...
Op´erateurs de fusion `a quota
Opérateurs de fusiona quota
Le Centre pour la Communication Scientifique Directe - HAL - memSIC, May 6, 2013
Belief merging aims at extracting a coherent and informative view from a set of belief bases. A f... more 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.
Belief merging aims at defining the beliefs of a group of agents from the beliefs of each member ... more Belief merging aims at defining the beliefs of a group of agents from the beliefs of each member of the group. It is related to more general notions of aggregation from economics (social choice theory). Two main subclasses of belief merging operators exist: majority operators which are related to utilitarianism, and arbitration op-erators which are related to egalitarianism. Though util-itarian (majority) operators have been extensively stud-ied so far, there is much less work on egalitarian op-erators. In order to fill the gap, we investigate possi-ble translations in a belief merging framework of some egalitarian properties and concepts coming from social choice theory, such as Sen-Hammond equity, Pigou-Dalton property, median, and Lorenz curves. We study how these properties interact with the standard ratio-nality conditions considered in belief merging. Among other results, we show that the distance-based merging operators satisfying Sen-Hammond equity are mainly those for which...
Compositional Belief Merging
Belief merging aims at extracting a coherent and informative view from a set of belief bases. A f... more 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.
Main Issues in Belief Revision, Belief Merging and Information Fusion
A Guided Tour of Artificial Intelligence Research, 2020
This chapter focuses on the dynamics of information represented in logical or numerical formats, ... more This chapter focuses on the dynamics of information represented in logical or numerical formats, from pioneering works to recent developments. The logical approach to belief change is a topic that has been extensively studied in Artificial Intelligence, starting in the mid-seventies. In this problem, logical formulas represent beliefs held by an intelligent agent that must be revised upon receiving new information that conflicts with prior beliefs and usually has priority over them. In contrast, in the merging problem, the logical theories that must be combined have equal priority. Such logical approaches recalled here make sense for merging beliefs as well as goals, even if each of these problems cannot be reduced to the other. In the last part, we discuss a number of issues pertaining to the fusion and the revision of uncertainty functions representing epistemic states, such as probability measures, possibility measures and belief functions. The need to cope with logical inconsistency plays a major role in these problems. The ambition of this chapter is not to provide an exhaustive bibliography, but rather to propose an overview of basic notions, main results and new research issues in this area.
There are two main sub-families of IC merging operators : majority operators and arbitration ones... more There are two main sub-families of IC merging operators : majority operators and arbitration ones. While many majority belief merging operators have been defined so far, only few arbitration belief merging operators have been identified. In this paper, we study the more general notion of egalitarian belief merging. We translate to the belief merging framework two egalitarian conditions coming from social choice theory : Sen-Hammond equity, and Pigou-Dalton property. We show that the distance-based merging operators satisfying Sen-Hammond equity are mainly those for which leximax is used as the aggregation function. We also introduce two new families of belief merging operators, based respectively on the median and on an aggregated sum (Lorenz curves). We identify the rationality properties satisfied by these operators and study in particular their egalitarian behaviour.
We have investigated the use of continuous alternatives for action selection by a behavior-orient... more We have investigated the use of continuous alternatives for action selection by a behavior-oriented agent. Such an agent is made of concurrent “behaviors”; each of these behaviors reacts to specific stimuli and provides a response according to a low-level goal. Since the behaviors are specialized, they can provide concurrent responses and conflicts among them must be solved to perform a coherent global behavior of the agent. In this context, voting methods allow to select only one of the responses of the behaviors, while taking into account their preferences and respecting all of their constraints. Previous works are based on action spaces limited to few discrete values and have shown difficulties in determining the behaviors weights for the vote. Furthermore, these works generally not allow to express the indifference of a behavior on a alternative’s component, i.e. the fact that a behavior has no preference on the value of one component of an alternative. We propose in this articl...
Proceedings of the Eighteenth International Conference on Principles of Knowledge Representation and Reasoning, 2021
In this work, we explore the links between the Borda voting rule and belief merging operators. Mo... more In this work, we explore the links between the Borda voting rule and belief merging operators. More precisely, we define two families of merging operators inspired by the definition of the Borda voting rule. We also introduce a notion of cancellation in belief merging, inspired by the axiomatization of the Borda voting rule proposed by Young. This allows us to provide a characterization of the drastic merging operator.
The aim of judgment aggregation is to make collective decisions based on the judgments of individ... more The aim of judgment aggregation is to make collective decisions based on the judgments of individual agents. Some rationality conditions governing the expected behavior of the aggregation function must be considered. However, impossibility theorems show that designing an aggregation function satisfying all desirable properties is not feasible. While some rationality conditions are very natural ones, other ones are more disputable. We show that this is the case of the systematicity condition that prevents from electing issues with more votes than others. Instead, a neutrality condition and a swap optimality condition are promoted. Swap optimality ensures that among two possible results, the one with the best support (number of votes) is chosen. We introduce a new family of judgment aggregation methods based on the support (number of votes) that each issue receives.
e Epistemic View of Belief Merging: Can We Track the Truth?
principles of knowledge representation and reasoning, Jul 1, 2014
Belief merging aims at defining the beliefs of a group of agents from the beliefs of each member ... more Belief merging aims at defining the beliefs of a group of agents from the beliefs of each member of the group. It is related to more general notions of aggregation from economics (social choice theory). Two main subclasses of belief merging operators exist: majority operators which are related to utilitarianism, and arbitration operators which are related to egalitarianism. Though utilitarian (majority) operators have been extensively studied so far, there is much less work on egalitarian operators. In order to fill the gap, we investigate possible translations in a belief merging framework of some egalitarian properties and concepts coming from social choice theory, such as Sen-Hammond equity, Pigou-Dalton property, median, and Lorenz curves. We study how these properties interact with the standard rationality conditions considered in belief merging. Among other results, we show that the distance-based merging operators satisfying Sen-Hammond equity are mainly those for which leximax is used as the aggregation function.
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Papers by patricia everaere