Consensus, communication and knowledge : an extension with bayesian agents

Parikh and Krasucki [1990] showed that pairwise communication of the value of a function f leads to a consensus about the communicated value if the function f is convex. They showed that union consistency of f may not be sufficient to guarantee consensus in any communication protocol. Krasucki [1996] proved that consensus occurs for any union consistent function if the protocol contains no cycle. We show that if agents communicate their optimal action, namely the action that maximizes their expected utility, then consensus obtains in any fair protocol for any action space.Consensus, common knowledge, pairwise communication.

Communication, consensus and order. Who wants to speak first ?

Parikh and Krasucki [1990] showed that if rational agents communicate the value of a function f according to a protocol upon which they have agreed beforehand, they will eventually reach a consensus about the value of f, provided a fairness condition on the protocol and a convexity condition on the function f. In this article, we address the issue of how agents agree on a communication protocol in the case where they communicate in order to learn information. We show that if it is common knowledge among a group of agents that some of them disagree about two protocols, then the consensus value of f must be the same according to the two protocols.Common knowledge, consensus, communication protocol.

Consensus, communication and knowledge: an extension with bayesian agents

URL des Cahiers : https://halshs.archives-ouvertes.fr/CAHIERS-MSEVoir aussi l'article basé sur ce document de travail paru dans "Mathematical Social Sciences", 51, 3, 2006, pp. 274-279Cahiers de la MSE 2005.31 - Série Verte - ISSN : 1624-0340Parikh and Krasucki [1990] showed that pairwise communication of the value of a function f leads to a consensus about the communicated value if the function f is convex. They showed that union consistency of f may not be sufficient to guarantee consensus in any communication protocol. Krasucki [1996] proved that consensus occurs for any union consistent function if the protocol contains no cycle. We show that if agents communicate their optimal action, namely the action that maximizes their expected utility, then consensus obtains in any fair protocol for any action space.On étend le résultat de Parikh et Krasucki [1990] au cas où l'ensemble des décisions possibles est quelconque. On montre que si les agents sont bayésiens et choisissent à chaque période l'action qui maximise leur espérance d'utilité, alors la communication de bouche à oreille conduit à l'égalité de toutes les décisions

Market power and voluntary land redistribution

Inequality in land ownership remains a major issue in many developing countries, such as Brazil, Colombia, and South Africa. Donors advocate a new model of "willing-buyer/willing-seller\", market-led land redistribution, but actual redistribution has fallen short of expectations. Little effort has been made so far to formalize the obstacles to market-led land redistribution. In this paper, we show that oligopolistic owner-producers may resist land sales to poorer candidate-buyers not only because they have a lower willingness to pay for land but also because the entry of poorer entrants threatens tacit collusion

Communication, consensus and order. Who wants to speak first?

URL des Cahiers : https://halshs.archives-ouvertes.fr/CAHIERS-MSEVoir aussi l'article basé sur ce document de travail paru dans "Journal of Economic Theory", 143, 1, 2008, pp. 140-152Cahiers de la MSE 2005.30 - Série Verte - ISSN : 1624-0340Parikh and Krasucki [1990] showed that if rational agents communicate the value of a function f according to a protocol upon which they have agreed beforehand, they will eventually reach a consensus about the value of f, provided a fairness condition on the protocol and a convexity condition on the function f. In this article, we address the issue of how agents agree on a communication protocol in the case where they communicate in order to learn information. We show that if it is common knowledge among a group of agents that some of them disagree about two protocols, then the consensus value of f must be the same according to the two protocols.On considère un comité d'experts qui ont à faire une recommandation à un decision maker. On modélise la phase précédente de débat, au cours de laquelle les experts doivent se mettre d'accord sur une recommandation à faire au decision maker. Avant de débattre, les experts doivent se mettre d'accord sur une règle de débat, c'est à dire un protocole de communication. On suppose que les experts communiquent en s'envoyant des messages selon une règle fixée, supposée union-consistent. On montre d'abord que quel que soit le protocole, le débat conduit au consensus entre les experts. On montre aussi que cette recommandation de consensus dépend du protocole. En supposant que un expert préfère les ordres de parole qui le laissent mieux informé, il peut y avoir des considérations stratégiques au choix d'un protocole de communication. On pose ainsi la question de savoir si un accord est toujours trouvé entre les experts ou pas. On montre qu'il peut être connaissance commune parmi les experts qu'ils préfèrent tous le même protocole, comme il peut être connaissance commune que certains ne sont pas d'accord sur le protocole à utiliser. On montre ensuite que dans ce dernier cas, les recommandations données à l'issue du débat sont les mêmes, donc un protocole peut être imposé sans conséquences sur la recommandation

La modélisation au coeur de l'apprentissage des sciences expérimentales : la digestion

La digestion au cycle 3 : un sujet d'apprentissage abordant de nombreux concepts complexes, difficiles à enseigner par l'impossibilité de visualiser et de manipuler le réel. Afin de proposer une alternative à ces obstacles, ce mémoire présente une séquence pour des élèves de CM1 basée sur cinq modélisations : une pour permettre une représentation juste du tube digestif et quatre autres pour visualiser et comprendre les actions mécaniques et le rôle de la digestion. De nombreuses questions se sont naturellement imposées lors de notre pratique. Ainsi, à partir de l'étude des modèles pédagogiques existants et l'utilisation de la modélisation comme outil et support à l'apprentissage, nous avons tenté de dégager les apports et les limites de celle-ci dans l'évolution des conceptions initiales des élèves et dans l'acquisition de nouvelles notions

Communication, consensus et ordre de parole. Qui veut parler en premier ?

Accessible en ligne sur le site : http://www.lamsade.dauphine.fr/Annales du LAMSADE n°8Parikh et Krasucki [1990] montrent que si des agents communiquent la valeur d'une fonction f selon un protocole sur lequel ils se sont préalablement entendus, alors ils atteindront un consensus sur la valeur de f, à condition que le protocole soit équitable et la fonction f convexe. On remarque que la valeur consensuelle de f ainsi que le montant d'information apprise par les agents au cours du processus de communication dépendent du protocole choisi. Si les agents communiquent afin d'apprendre de l'information, il est alors possible que certains d'entre eux soient en désaccord quant au protocole de communication à utiliser. On montre que s'il est connaissance commune que deux agents ont des préférences opposées sur deux protocoles, alors le consensus qui émergerait de l'utilisation de l'un ou l'autre protocole est le même. Parikh and Krasucki [1990] showed that if rational agents communicate the value of a function f according to a protocol upon which they have agreed beforehand, they will eventually reach a consensus about the value of f, provided a fairness condition on the protocol and a convexity condition on the function f. In this article, we address the issue of how agents agree on a communication protocol in the case where they communicate in order to learn information. We show that if it is common knowledge among a group of agents that some of them disagree about two protocols, then the consensus value of f must be the same according to the two protocols

Toward the use of proxies for efficient learning manipulation and locomotion strategies on soft robots

Soft robots are naturally designed to perform safe interactions with their environment, like locomotion and manipulation. In the literature, there are now many concepts, often bio-inspired, to propose new modes of locomotion or grasping. However, a methodology for implementing motion planning of these tasks, as exists for rigid robots, is still lacking. One of the difficulties comes from the modeling of these robots, which is very different, as it is based on the mechanics of deformable bodies. These models, whose dimension is often very large, make learning and optimization methods very costly. In this paper, we propose a proxy approach, as exists for humanoid robotics. This proxy is a simplified model of the robot that enables frugal learning of a motion strategy. This strategy is then transferred to the complete model to obtain the corresponding actuation inputs. Our methodology is illustrated and analyzed on two classical designs of soft robots doing manipulation and locomotion tasks.Comment: Accepted at IEEE Robotics and Automation Letters (RAL) in October 202

Generation of Arbitrary Frequency Chirps with a Fiber-Based Phase Modulator and Self-Injection-Locked Diode Laser

We present a novel technique for producing pulses of laser light whose frequency is arbitrarily chirped. The output from a diode laser is sent through a fiber-optical delay line containing a fiber-based electro-optical phase modulator. Upon emerging from the fiber, the phase-modulated pulse is used to injection-lock the laser and the process is repeated. Large phase modulations are realized by multiple passes through the loop while the high optical power is maintained by self-injection-locking after each pass. Arbitrary chirps are produced by driving the modulator with an arbitrary waveform generator