Long information design

We analyze information design games between two designers with opposite preferences and a single agent. Before the agent makes a decision, designers repeatedly disclose public information about persistent state parameters. Disclosure continues until no designer wishes to reveal further information. We consider environments with general constraints on feasible information disclosure policies. Our main results characterize equilibrium payoffs and strategies of this long information design game and compare them with the equilibrium outcomes of games where designers move only at a single predetermined period. When information disclosure policies are unconstrained, we show that at equilibrium in the long game, information is revealed right away in a single period; otherwise, the number of periods in which information is disclosed might be unbounded. As an application, we study a competition in product demonstration and show that more information is revealed if each designer could disclose information at a predetermined period. The format that provides the buyer with most information is the sequential game where the last mover is the ex-ante favorite seller

ON TWO-PLAYER REPEATED GAMES WITH LACK OF INFORMATION ON ONE SIDE AND STATE-INDEPENDENT SIGNALLING

We consider two-person undiscounted repeated games with lack of information on one side and state-independent signalling and prove the existence of a “joint plan” uniform equilibrium

A folk theorem for finitely repeated games with public monitoring

We adapt the methods from Abreu, Pearce and Stacchetti (1990) to finitely repeated games with imperfect public monitoring. Under a combination of (a slight strengthening of) the assumptions of Benoît and Krishna (1985) and those of Fudenberg, Levine and Maskin (1994), a folk theorem follows. Three counterexamples show that our assumptions are tight

Existence of the uniform value in repeated games

Dans cette thèse, nous nous intéressons à un modèle général de jeux répétés à deux joueurs et à somme nulle et en particulier au problème de l existence de la valeur uniforme. Un jeu répété a une valeur uniforme s il existe un paiement que les deux joueurs peuvent garantir, dans tous les jeux commençant aujourd hui et suffisamment longs, indépendamment de la longueur du jeu. Dans un premier chapitre, on étudie les cas d un seul joueur, appelé processus de décision Markovien partiellement observable, et des jeux où un joueur est parfaitement informé et contrôle la transition. Il est connu que ces jeux admettent une valeur uniforme. En introduisant une nouvelle distance sur les probabilités sur le simplexe de Rm, on montre l existence d une notion plus forte où les joueurs garantissent le même paiement sur n importe quel intervalle de temps suffisamment long et non pas uniquement sur ceux commençant aujourd hui. Dans les deux chapitres suivants, on montre l existence de la valeur uniforme dans deux cas particuliers de jeux répétés : les jeux commutatifs dans le noir, où les joueurs n observent pas l'état mais l état est indépendant de l ordre dans lequel les actions sont jouées, et les jeux avec un contrôleur plus informé, où un joueur est plus informé que l autre joueur et contrôle l'évolution de l'état. Dans le dernier chapitre, on étudie le lien entre la convergence uniforme des valeurs des jeux en n étapes et le comportement asymptotique des stratégies optimales dans ces jeux en n étapes. Pour chaque n, on considère le paiement garanti pendant ln étapes avec 0 < l < 1 par les stratégies optimales pour n étapes et le comportement asymptotique lorsque n tend vers l infini.In this dissertation, we consider a general model of two-player zero-sum repeated game and particularly the problem of the existence of a uniform value. A repeated game has a uniform value if both players can guarantee the same payoff in all games beginning today and sufficiently long, independently of the length of the game. In a first chapter, we focus on the cases of one player, called Partial Observation Markov Decision Processes, and of Repeated Games where one player is perfectly informed and controls the transitions. It is known that these games have a uniform value. By introducing a new metric on the probabilities over a simplex in Rm, we show the existence of a stronger notion, where the players guarantee the same payoff on all sufficiently long intervals of stages and not uniquely on the one starting today. In the next two chapters, we show the existence of the uniform value in two special models of repeated games : commutative repeated games in the dark, where the players do not observe the state variable, but the state is independent of the order the actions are played, and repeated games with a more informed controller, where one player controls the transition and has more information than the second player. In the last chapter, we study the link between the uniform convergence of the value of the n-stage games and the asymptotic behavior of the sequence of optimal strategies in the n-stage game. For each n, we consider n-stage optimal strategies and the payoff they are guaranteeing during the ln first stages with 0 < l < 1. We study the asymptotic of this payoff when n goes to infinity.TOULOUSE1-SCD-Bib. electronique (315559902) / SudocSudocFranceF

Value-based distance between information structures

We define the distance between two information structures as the largest possible difference in value across all zero-sum games. We provide a tractable characterization of distance and use it to discuss the relation between the value of information in games versus single-agent problems, the value of additional information, informational substitutes, complements, or joint information. The convergence to a countable information structure under value-based distance is equivalent to the weak convergence of belief hierarchies, implying, among other things, that for zero-sum games, approximate knowledge is equivalent to common knowledge. At the same time, the space of information structures under the value-based distance is large: there exists a sequence of information structures where players acquire increasingly more information, and ε > 0 such that any two elements of the sequence have distance of at least ε. This result answers by the negative the second (and last unsolved) of the three problems posed by Mertens in his paper“Repeated Games” (1986)

Competition and Recall in Selection Problems

We extend the prophet inequality problem to a competitive setting. At every period, a new realization of a random variable with a known distribution arrives, which is publicly observed. Then two players simultaneously decide whether to pick an available value or to pass and wait until the next period (ties are broken uniformly at random). As soon as a player gets a value, he leaves the market and his payoff is the value of this realization. In the first variant, namely the “no recall” case, the agents can only bid at each period for the current value. In a second variant, the “full recall” case, the agents can also bid for any of the previous realizations which has not been already selected. For each variant, we study the subgame-perfect Nash equilibrium payoffs of the corresponding game. More specifically, we give a full characterization in the full recall case and show in particular that the expected payoffs of the players at any equilibrium are always equal, whereas in the no recall case the set of equilibrium payoffs typically has full dimension. Regarding the welfare at equilibrium, surprisingly the best equilibrium payoff a player can have may be strictly higher in the no recall case. However, the sum of equilibrium payoffs is weakly larger when the players have full recall. Finally, we show that in the case of 2 arrivals and arbitrary distributions, the prices of Anarchy and Stability in the no recall case are at most 4/3, and this bound is tight

Long information design

National audienceWe analyze information design games between two designers with opposite preferences and a single agent. Before the agent makes a decision, designers repeatedly disclose public information about persistent state parameters. Disclosure continues until no designer wishes to reveal further information. We consider environments with general constraints on feasible information disclosure policies. Our main results characterize equilibrium payoffs and strategies of this long information design game and compare them with the equilibrium outcomes of games where designers move only at a single predetermined period. When information disclosure policies are unconstrained, we show that at equilibrium in the long game, information is revealed right away in a single period; otherwise, the number of periods in which information is disclosed might be unbounded. As an application, we study a competition in product demonstration and show that more information is revealed if each designer could disclose information at a pre-determined period. The format that provides the buyer with most information is the sequential game where the last mover is the ex-ante favorite seller

Electronic Structure and Solvation Effects from Core and Valence Photoelectron Spectroscopy of Serum Albumin

International audienceX-ray photoelectron spectroscopy of bovine serum albumin (BSA) in a liquid jet is used to investigate the electronic structure of a solvated protein, yielding insight into charge transfer mechanisms in biological systems in their natural environment. No structural damage was observed in BSA following X-ray photoelectron spectroscopy in a liquid jet sample environment. Carbon and nitrogen atoms in different chemical environments were resolved in the X-ray photoelectron spectra of both solid and solvated BSA. The calculations of charge distributions demonstrate the difficulty of assigning chemical contributions in complex systems in an aqueous environment. The high-resolution X-ray core electron spectra recorded are unchanged upon solvation. A comparison of the valence bands of BSA in both phases is also presented. These bands display a higher sensitivity to solvation effects. The ionization energy of the solvated BSA is determined at 5.7 ± 0.3 eV. Experimental results are compared with theoretical calculations to distinguish the contributions of various molecular components to the electronic structure. This comparison points towards the role of water in hole delocalization in proteins