### Seminars

# The Parisian Seminar of Game Theory

The Parisian Seminar of Game Theory takes place on Monday from 11 to 12. The location is Centre Emile Borel de l’Institut Henri Poincare, 11 rue Pierre et Marie Curie, Paris 5ème, room 01 (ground floor).

Administrative correspondant: Sophie Gozlan

This seminar is organized by Marie Laclau, Lucie Ménager, Xavier Venel, Bruno Ziliotto

- Go to the seminar website : https://sites.google.com/view/seminairetheoriedesjeux/
- To register to the seminar mailing list, please write to : lucie.menager u-paris2.fr

This seminar is co-funded by a French government subsidy managed by the Agence Nationale de la Recherche under the framework of the Investissements d’avenir programme reference ANR-17-EURE-0001.

## Upcoming events

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## Archives

**Monday 28 June 2021 11:00-12:00**- Online
**BOURSIER Etienne**(ENS Paris-Saclay) :__Decentralized Learning in Online Queuing Systems__- AbstractMotivated by packet routing in computer networks, online queuing systems are composed of queues receiving packets at different rates. Repeatedly, they send packets to servers, each of them treating only at most one packet at a time. In the centralized case, the number of accumulated packets remains bounded (i.e., the system is stable) as long as the ratio between service rates and arrival rates is larger than 1. In the decentralized case, individual no-regret strategies ensures stability when this ratio is larger than 2. Yet, myopically minimizing regret disregards the long term effects due to the carryover of packets to further rounds. On the other hand, minimizing long term costs leads to stable Nash equilibria as soon as the ratio exceeds e/(e-1). Stability with decentralized learning strategies with a ratio below 2 was a major remaining question. We first argue that for ratios up to 2, cooperation is required for stability of learning strategies, as selfish minimization of policy regret, a patient notion of regret, might indeed still be unstable in this case. We therefore consider cooperative queues and propose the first learning decentralized algorithm guaranteeing stability of the system as long as the ratio of rates is larger than 1, thus reaching performances comparable to centralized strategies.

**Monday 21 June 2021 11:00-12:00**- Online
**RENAULT Jérôme**(TSE) :__Strategic Information transmission with sender’s approval__**Co-author: Françoise Forges**- AbstractWe consider sender–receiver games in which the sender has finitely many types and the receiver makes a decision in a compact set. The new feature is that, after the cheap talk phase, the receiver makes a proposal to the sender, which the latter can reject in favor of an outside option. We focus on situations in which the sender’s approval is absolutely crucial to the receiver, namely, on equilibria in which the sender does not exit at the approval stage. We show that if the sender has only two types or if the receiver’s preferences over decisions do not depend on the type of the sender, there exists a (perfect Bayesian Nash) partitional equilibrium without exit, in which the sender transmits information by means of a pure strategy. The previous existence results do not extend: we construct a counter-example (with three types for the sender and type-dependent utility functions) in which there is no equilibrium without exit, even if the sender can randomize over messages. Communication equilibria without exit always exist in the three type case, and the question is open for 4 or more types.

**Monday 14 June 2021 11:00-12:00**- Online
**PIZARRO Dana**(TSE) :__On a competitive selection problem with recall__- AbstractWe consider a problem where items arrive sequentially over time and two agents compete to choose the best possible item. We describe the game induced by the problem in two settings: one in which only take-it-or-leave-it strategies are allowed and another where it is possible to select an item that appeared in the past, if it is still available. We study the set of subgame perfect Nash equilibrium payoffs and we find tight bounds for the Price of Anarchy and Price of Stability of the latter setting when the number of arrivals is two.

**Monday 31 May 2021 11:00-12:00**- Online
**PATTY Morgan**(LEDa, PSL) :__Top Dominance__- AbstractTo deal with issues of inconsistency faced by iterated elimination of weakly or strictly dominated strategies (IEWDS or IESDS), we propose a new elimination procedure. Our procedure, named iterated elimination of top dominated strategies (IETDS), is based on the new notion of top dominance. It is more consistent than IESDS in a certain sense. Top dominance is more restrictive than weak dominance (and may be more restrictive than strict dominance): it requires weak dominance and strict payoff domination of the strategy on a specific profiles set. Furthermore, it requires that the dominating strategy to be not weakly dominated. Contrary to IESDS, IETDS may reduce the set of Nash equilibria (whilst never eliminating strict Nash equilibria) without the problems of order dependence, mutability and spurious Nash equilibria encountered by IEWDS and IESDS.

**Monday 17 May 2021 11:00-12:00**- Online
**FLESCH Janos**(Maastricht University) :__A competitive search game with a moving target__- AbstractThe talk is based on two papers. The first is joint work with Benoit Duvocelle, Mathias Staudigl, Dries Vermeulen, and the second with Benoit Duvocelle, Hui Min Shi, Dries Vermeulen. Abstract: We introduce a discrete-time search game, in which two players compete to find an object first. The object moves according to a time-varying Markov chain on finitely many states. The players know the Markov chain and the initial probability distribution of the object, but do not observe the current state of the object. The players are active in turns. The active player chooses a state, and this choice is observed by the other player. If the object is in the chosen state, the active player wins and the game ends. Otherwise, the object moves according to the Markov chain and the game continues at the next period. We show that this game admits a value, and for any error-term epsilon>0, each player has a pure (subgame-perfect) epsilon-optimal strategy. Interestingly, a 0-optimal strategy does not always exist. We derive results on the properties of the value and the epsilon-optimal strategies. Moreover, we examine the performance of the finite truncation strategies. We devote special attention to the time-homogeneous case, where additional results hold. We also investigate a related model, where the active player is chosen randomly at each period. In this case, the results are quite different, and greedy strategies (which always recommend to choose a state that contains the object with the highest probability) play the main role

**Monday 10 May 2021 11:00-12:00**- online
**DEMEZE-JOUATSA Ghislain-Herman**(Bielefeld University) :__Repetition and cooperation: a model of finitely repeated games with objective ambiguity__- AbstractWe present a model of repeated games in which players can strategically make use of objective ambiguity. In each round of the repeated game, in addition to the classic pure and mixed actions, players can employ objectively ambiguous actions by using imprecise probabilistic devices such as Ellsberg urns to conceal their intentions. We find that adding an infinitesimal level of ambiguity can be enough to approximate collusive payoffs via subgame perfect equilibrium strategies of the finitely repeated game. Our main theorem states that if each player has many continuation equilibrium payoffs in ambiguous actions, any feasible payoff vector of the original stage-game that dominates the mixed strategy maxmin payoff vector is both ex-ante and ex-post approachable by means of subgame perfect equilibrium strategies of the finitely repeated game with discounting. Our condition is also necessary.

**Monday 3 May 2021 11:00-12:00**- online
**FEUILLOLEY Laurent**(LIRIS,CNRS, Université Lyon 1) :__The Secretary Problem with Independent Sampling__**Co-authors: José Correa, Andrés Cristi, Tim Oosterwijk, and Alexandros Tsigonias-Dimitriadis**- AbstractThe secretary problem is a classic online decision problem. In this problem, an adversary first chooses some n numbers, then these numbers are shuffled at random and presented to the player one by one. For each number, the player has two options: discard the number and continue, or keep the number and stop the game. The player wins if she keeps the highest number of the whole set. It is clearly not possible to win all the time: when one decides to stop there might be a higher number in the rest of the sequence, and when one discards a number, it might actually be the highest of the sequence. But surprisingly one can win with probability 1/e. This has been known for several decades. An issue with the secretary problem is that it assumes that the player has absolutely no information about the numbers, which reduces its applicability. A recent research direction is to understand what happens when one knows a distribution or samples etc. We study a simple such setting for which we prove tight results.

**Monday 8 February 2021 11:00-12:00**- online
**KOESSLER Frédéric**(PSE) :__Information Design by an Informed Designer__**Co-author : Vasiliki Skreta**- AbstractA designer is privately informed about the state and chooses an information disclosure mechanism to influence the decisions of multiple agents playing a game. We define an intuitive class of incentive feasible information disclosure mechanisms which we coin interim optimal mechanisms. We prove that an interim optimal mechanism exists, and that it is an equilibrium outcome of the interim information design game. An ex-ante optimal mechanism may not be interim optimal but it is in leading settings in which action sets are binary. Likewise, in settings in which an ex-ante optimal mechanism is full disclosure then it is interim optimal. We relate interim optimal mechanisms with other solutions of informed designer problems.

**Monday 1 February 2021 11:00-12:00**- online
**LOVO Stefano**(HEC) :__Socially responsible finance: How to Optimize Impact?__**Co-author : Augustin Landier**- AbstractWe consider a general equilibrium productive economy with negative externalities. Investors seek to maximize returns, entrepreneurs profits, and a socially responsible fund social welfare. We show that the fund is able to raise assets and improve social welfare iff: (i) it commits to finance only firms that cap their emissions and (ii) capital allocation is subject to frictions. The fund should prioritize investments in companies with acute negative externalities and facing strong capital search friction. It can amplify its impact by imposing restrictions on the suppliers of the firms it finances. Investing in already clean sectors has no impact.

**Monday 25 January 2021 11:00-12:00**- on line
**JAIN Atulya**:__Dynamic cheap talk with no feedback__- AbstractWe study a dynamic sender-receiver game, where the sequence of states follows a Markov chain. The sender provides valuable information but gets no feedback on the receiver’s actions. Under certain assumptions, we characterize the set of uniform equilibrium payoffs with the help of a static cheap talk game, where the marginal distribution of messages is fixed. We show that the sender is able to bridge the value of commitment and secure the Bayesian persuasion payoff of the static game.

**Tuesday 19 January 2021**- Workshop Games, Approachability and Learning
- Full text [pdf]

**Monday 18 January 2021**- Workshop Games, Approachability and Learning
- Full text [pdf]

**Monday 11 January 2021 11:00-12:00**- Zoom : https://hec-fr.zoom.us/j/95796468806 ID de réunion : 957 9646 8806
**GAUBERT Stéphane**(INRIA, CMAP, Ecole Polytechnique) :__The geometry of fixed points sets of Shapley operators__**Marianne Akian and Sara Vannucci**- AbstractShapley operators of undiscounted zero-sum two-player games are order-preserving maps that commute with the addition of a constant. The fixed points of these Shapley operators play a key role in the study of games with mean payoff: the existence of a fixed point is guaranteed by ergodicity conditions, moreover, fixed points that are distinct (up to an additive constant) determine distinct optimal stationary strategies. We provide a series of characterizations of fixed point sets of Shapley operators in finite dimension (i.e., for games with a finite state space). Some of these characterizations are of a lattice theoretical nature, whereas some other rely on metric geometry and tropical geometry. More precisely, we show that fixed point sets of Shapley operators are special instances of hyperconvex spaces (non-expansive retracts of sup-norm spaces) that are lattices in the induced partial order. They are also characterized by a property of ``best co-approximation'' arising in the theory of nonexpansive retracts of Banach spaces. Moreover, they retain properties of convex sets, with a notion of ``convex hull'' defined only up to isomorphism. We finally examine the special case of deterministic games with finite action spaces. Then, fixed point sets have a structure of polyhedral complexes, which include as special cases tropical polyhedra. These complexes have a cell decomposition attached to stationary strategies of the players, in which each cell is an alcoved polyhedron of An type.

**Monday 4 January 2021 11:00-12:00****RAGEL Thomas**(CEREMADE, Dauphine PSL) :__TBA__

**Monday 14 December 2020 11:00-12:00**- On line
**MARLATS Chantal**(LEMMA, Paris 2) :__Voluntary confinement__

**Monday 2 November 2020 11:00-12:00**- A simple refinement of sequential equilibria
- AbstractWe provide a simple refinement of sequential equilibria in generic finite extensive form games. In these equilibria, at information sets that are one (agent) deviation away from the equilibrium path, the beliefs put positive probability only on those nodes which can be reached by one deviation of an agent. Namely, multiple deviations of agents are infinitely less likely than a single deviation of a single agent. In generic games Mertens stable outcomes can be supported with such a belief.

**Monday 12 October 2020 11:00-12:00**- room 314 (third floor) at Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème.
**PEREZ-RICHET Eduardo**(Sciences Po, département d’économie) :__Test design with unobservable falsification__- AbstractWe study receiver-optimal test design under manipulations by an agent who can falsify the data input of the test. We characterize an optimal test and an optimal falsification proof tests under different assumptions on the cost function, and discuss the welfare properties of such tests.

**Monday 5 October 2020 11:00-12:00**- room 314 (third floor) at Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème.
**AMOUSSOU-GUENOU Yackolley**(CEA List & LIP6, Sorbonne Université) :__Is distributed consensus possible in committee-based blockchains?__- AbstractWe study the rational behaviors of participants in committee-based blockchains. Committee-based blockchains rely on specific blockchain consensus that must be guaranteed in presence of rational participants. We consider a simplified blockchain consensus algorithm based on existing or proposed committee-based blockchains that encapsulates the main actions of the participants: voting for a block, and checking its validity. Knowing that those actions have costs, and achieving the consensus gives rewards to committee members, we study using game theory how strategic players behave while trying to maximizing their gains.

**Monday 28 September 2020 11:00-12:00**- either amphi Hermite (ground floor) or room 314 (third floor) at Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**SALAMANCA Andrés**(PSE) :__Biased Mediators in Conflict Resolution__- AbstractWhat is the role of biased mediators for reaching negotiated settlements in social conflicts? Previous empirical research in Political Sciences has suggested that mediators are often more effective if they are unbiased (or impartial).This research contributes to the previous debate following a game theoretic analysis. We study a model of cheap-talk in which an agent possesses private information about a binary state of the world. This information is required by an uninformed principal in order to take an action in the real line. Individuals have quadratic preferences, with a difference in their bliss point parameterized by a state-dependent bias parameter. Therefore, a conflict of interests between both parties arises because of a discrepancy in their bliss point. Provided that mediation is beneficial for at least one party, we show that whenever the variation of the bias across states is large enough, the agent will refuse to participate in a mediation process that is biased towards the principal. Otherwise, the mediator’s bias is inconsequential for reaching an agreement, hence a biased mediator is as effective as an unbiased one.

**Monday 25 May 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**SHMAYA Eran**:__*__

**Monday 18 May 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**SMOLIN Alex**(TSE) :__*__

**Monday 27 April 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**LOVO Stefano**(HEC) :__*__

**Monday 30 March 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**RENOU Ludovic**(QMUL) :__*__

**Monday 16 March 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**LEVY John**:__*__

**Monday 9 March 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**KRÄHMER Daniel**:__*__

**Monday 2 March 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**ZSELEVA Anna**:__*__

**Monday 27 January 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**MERTIKOPOULOS Panayotis**:__*__

**Monday 20 January 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**MATYSKOVA Ludmila**:__*__

**Monday 13 January 2020 11:00-12:00**- Institut Henri Poincaré - 11 rue Pierre et Marie Curie - 75005 Paris
**GAUJAL Bruno**:__*__

**Monday 16 December 2019 11:00-12:00**- Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**PAWLOWITSCH Christina**(Université Panthéon-Assas, LEMMA) :__Evolutionary dynamics of costly signaling__**Josef Hofbauer**- AbstractCostly-signaling games have a remarkably wide range of applications (education as a costly signal in the job market, handicaps as a signal for fitness in mate selection, politeness in language). The formal analysis of evolutionary dynamics in costly-signaling games has only recently gained more attention. In this paper, we study evolutionary dynamics in two basic classes of games with two states of nature, two signals, and two possible reactions in response to signals: a discrete version of Spence’s (1973) model and a discrete version of Grafen’s (1990) formalization of the handicap principle. We first use index theory to give a rough account of the dynamic stability properties of the equilibria in these games. Then, we study in more detail the replicator dynamics and to some extent the best-response dynamics.

**Monday 9 December 2019 11:00-12:00**- Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**CORREA José**(Universidad de Chile) :__On the Price of Anarchy for flows over time__**Andres Cristi and Tim Oosterwijk**- AbstractDynamic network flows, or network flows over time, constitute an important model for real-world situations where steady states are unusual, such as urban traffic and the Internet. These applications immediately raise the issue of analyzing dynamic network flows from a game-theoretic perspective. In this paper we study dynamic equilibria in the deterministic fluid queuing model in single-source single-sink networks, arguably the most basic model for flows over time. In the last decade we have witnessed significant developments in the theoretical understanding of the model. However, several fundamental questions remain open. One of the most prominent ones concerns the Price of Anarchy, measured as the worst case ratio between the minimum time required to route a given amount of flow from the source to the sink, and the time a dynamic equilibrium takes to perform the same task. Our main result states that if we could reduce the inflow of the network in a dynamic equilibrium, then the Price of Anarchy is exactly e/(e ? 1) ? 1.582. This significantly extends a result by Bhaskar, Fleischer, and Anshelevich (SODA 2011). Furthermore, our methods allow to determine that the Price of Anarchy in parallel-link networks is exactly 4/3. Finally, we argue that if a certain very natural monotonicity conjecture holds, the Price of Anarchy in the general case is exactly e/(e ? 1).

**Monday 2 December 2019 11:00-12:00**- Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**GALICHON Alfred**(New York University) :__The equilibrium flow problem and multivocal gross substitutes__**Larry Samuelson and Lucas Vernet**- AbstractWe show that several classical economic models such as two-sided matching models, min-cost flow problems, hedonic models, and dynamic programming problems are subcases of a more general class of problems called equilibrium flow problems. To analyze this problem, we introduce a novel notion of gross substitutes for correspondences called "multivocal gross substitutes". We show that this notion generalizes some familiar notions of substitutes (such as weak gross substitutes) while strengthening others (such as that of Kelso and Crawford). Our main result, the inverse isotonicity theorem, establishes that if an excess supply correspondence satisfies multivocal gross substitutes, then the inverse correspondence is isotone in the strong set order, extending to the corresponding case results by Berry, Gandhi and Haile (2013). As another consequence, extend the lattice structure results of Demange and Gale (1985) to general networks beyond the bipartite case.

**Monday 25 November 2019 11:00-12:00**- Centre Emile Borel, Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**PREDTETCHINSKI Arkadi**:__Arkadi PREDTETCHINSKI__

**Monday 18 November 2019 11:30-12:30**- Centre Emile Borel, Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**MOULIN Hervé**(University of Glasgow) :__Toto__

**Monday 11 November 2019 11:00-12:00****RADJA prenom ...**:__Test service info__

**Monday 4 December 2017 11:00-12:00**- salle 01 (rez-de-chaussée) au Centre Emile Borel de l'Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**PRADELSKI Bary**(ETH Zurich) :__*__

**Monday 20 November 2017 11:00-12:00**- salle 01 (rez-de-chaussée) au Centre Emile Borel de l'Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
**CORREA José**(Universidad de Chile) :__*__

**Monday 6 November 2017 11:00-12:00**- Salle 01 (RDC), Centre Emile Borel, Institut Henri Poincaré, 11 rue Pierre et Marie Curie, 75005 Paris
**SAVANI Rahul**(University of Liverpool ) :__*__

**Monday 16 October 2017 11:00-12:00**- Salle 01 (RDC), Centre Emile Borel, Institut Henri Poincaré, 11 rue Pierre et Marie Curie, 75005 Paris
**SOLAN Eilan**(Tel Aviv University ) :__Optimal Dynamic Inspection__- AbstractWe study a discounted repeated inspection game with two agents and one principal. Both agents may pro.fit by violating certain rules, while the principal can inspect on at most one agent in each period, in.flicting a punishment on an agent who is caught violating the rules. The goal of the principal is to minimize the discounted number of violations, and he has a Stackelberg leader advantage. We characterize the principal's optimal inspection strategy.

**Monday 9 October 2017 11:00-12:00**- Salle 01 (RDC), Centre Emile Borel, Institut Henri Poincaré, 11 rue Pierre et Marie Curie, 75005 Paris
**MERTIKOPOULOS Panayotis**:__No-Regret Learning in Games__- AbstractIn many cases of practical interest, the players of a repeated game may not know the structure of the game being played - simply think of commuters driving to work every day, ignorant of the number of commuters at each part of the road. In such cases, it is often assumed that players follow a no-regret procedure, i.e. an updating policiy that provably minimizes each player's individual regret against any possible play of their opponents. This talk focuses on the following question: does the sequence of play induced by a no-regret learning process converge to an equilibrium of the underlying stage game? I will present some recent contributions to this question (in both finite and continuous games), and I will discuss the impact of the feedback available to the players.

**Monday 27 June 2016 11:00-12:00**- salle 01 (rez-de-chaussée) au Centre Emile Borel de l'Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème

**Monday 20 June 2016 11:00-12:00**

**Monday 13 June 2016 11:00-12:00**

**Monday 6 June 2016 11:00-12:00****ZACCOUR Georges****SCHROEDER Marc**

**Monday 30 May 2016 11:00-12:00**

**Monday 23 May 2016 11:00-12:00**

**Monday 9 May 2016 11:00-12:00****RITZBERGER Klaus**

**Monday 11 April 2016 11:00-12:00****SANTAMBROGIO**

**Monday 4 April 2016 11:00-12:00****LOVO Stefano**

**Monday 21 March 2016 11:00-12:00****QUINCAMPOIX Marc**

**Monday 14 March 2016 11:00-12:00****ZILIOTO Bruno**

**Monday 7 March 2016 11:00-12:00****RADY Sven**

**Monday 15 February 2016 11:15-12:15****MANNOR Shie**(Technion) :__Time Series Analysis Between stochastic and adversarial: forecasting with online ARMA model__

**Monday 15 February 2016 10:00-11:00****SOLAN Eilan**(Tel Aviv) :__Acceptable strategy profiles in stochastic games__

**Monday 8 February 2016 11:00-12:00****HERNANDEZ Penelope**(Valencia)

**Monday 1 February 2016 11:00-12:00**

**Monday 25 January 2016 11:00-12:00****HEINRICH Max**

**Monday 18 January 2016 11:00-12:00****FAURE Matthieu**

**Monday 11 January 2016 11:00-12:00****KLIMM Max**

**Monday 14 December 2015 11:00-12:00****LESSARD Sabin**

**Monday 7 December 2015 11:00-12:00****KANADE Varun**(ENS) :

**Monday 30 November 2015 11:00-12:00****BABICHENKO Yakov**:

**Monday 23 November 2015 11:00-12:00****PREDTETCHINSKI Arkadi**:__Optimal Stationary Strategies for lim sup Stochastic Games__

**Monday 16 November 2015 11:00-12:00****JEHIEL Philippe**:__Investment strategy and selection bias: An equilibrium perspective on overconfidence__

**Monday 9 November 2015 11:00-12:00****HART Sergiu**(the Hebrew University of Jerusalem) :__(1) The Query Complexity of Correlated Equilibria (with Noam Nisan), and (2) Smooth Calibration, Leaky Forecasts, and Finite Recall (with Dean P. Foster)__

**Monday 2 November 2015 11:00-12:00****WAN Cheng**(University of Oxford) :__Strategic decentralization in binary choice congestion games__

**Monday 3 December 2012 11:00-12:00**- Institut Henri Poincare 11, rue pierre et marie curie – 7500
**MENAGER Lucie**(Universités Panthéon-Assas et Lille 1) :__Strategic observation in bandit models__

**Monday 26 November 2012 11:00-12:00**- Institut Henri Poincare 11, rue pierre et marie curie – 7500
**TOIKKA Juuso Toikka**(MIT) :__Efficiency in games with markovian private information__

**Monday 26 November 2012 10:00-11:00**- Institut Henri Poincare 11, rue pierre et marie curie – 7500
**CARDALIAGUET Pierre**(Université Paris Dauphine) :__Some aspects of mean field games__

**Monday 19 November 2012 11:00-12:00**- Institut Henri Poincare 11, rue pierre et marie curie – 7500
**FLESCH Janos**(Maastricht University) :__On subgame-perfection in games with perfect information__

**Monday 12 November 2012 11:00-12:00**- Institute Henri Poincare - Centre Emile Borel - Salle 01 - r
**VIOSSAT Yannick**(Université Paris Dauphine) :__No-regret dynamics and fictitious-play__

**Monday 12 November 2012 11:00-12:00**- Institut Henri Poincare 11, rue pierre et marie curie – 7500
**VIOSSAT Yannick**(Université Paris Dauphine) :__No-regret dynamics and fictitious-play__

**Monday 17 September 2012 11:00-12:00**- Centre Emile Borel de l'Institut Henri Poincaré, 11 rue Pier
**WEINSTEIN Jonathan**(Northwestern University) :__Robustness in Repeated Games__

**Monday 30 April 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**VENEL Xavier**(TSE & Université Toulouse 1) :__A distance for probability spaces and long-term values in Markov Decision Processes and Repeated Games.__**Co-author(s): J. Renault**

**Monday 2 April 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**BALKENBORG Dieter**(Exeter University) :__Strict equilibrium sets__**Co-author(s): K. Schlag et D. Vermeulen**

**Monday 26 March 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**KANDORI Michihiro**(University of Tokyo) :__Asynchronous Revision Games__

**Monday 19 March 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**BRAVO Mario**(Université Paris 6) :__An Adjusted Payoff-Based Procedure for Normal Form Games__

**Monday 12 March 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**VERMEULEN Dries**(Maastricht University) :__*__

**Monday 5 March 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**LUGOSI Gabor**(Pompeu Fabra University) :__Regret in Online Combinatiorial Optimization__

**Monday 5 March 2012 10:00-11:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**HAMADENE Said**(Université du Maine) :__Multi-players Nonzero-sum Dynkin Game in continuous time__

**Monday 30 January 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**LE TREUST Maël**(Supélec) :__Correlation and min-max levels in repeated games with imperfect monitoring__

**Monday 23 January 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**WOZNY Lukasz**(Warsaw School of Economics) :__A Constructive study of Markov equilibria in stochastic games with strategic complementarities__

**Monday 16 January 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**RIEDEL Frank**(Bielefeld University) :__Strategic use of ambiguity__

**Monday 9 January 2012 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**SCARSINI Marco**(LUISS) :__Monopoly pricing in the presence of social learning__

**Monday 12 December 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**ETTINGER David**(Université Paris-Dauphine) :__o Deception in a repeated expert/agent interaction: theory and experiment__

**Monday 5 December 2011 11:00-12:00**- Institut Henri Poincare - Salle 5 ou Salle 314 ou 201
**MORTIMORT David**(PSE) :__Aggregate Representations of Aggregate Games__**Co-author(s): Lars Stole**

**Monday 28 November 2011 11:00-12:00****The session was canceled.**- Institut Henri Poincare - Salle 5, 314 ou 201
**MERTENS Jean-François**(CORE, Université de Louvain) :__Shapley value with a continuum of agents: stable bridges with index 1__

**Monday 21 November 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**PERETZ Ron**(Tel Aviv University) :__The entropy method and repeated games with bounded complexity__

**Monday 14 November 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**ZAPECHLNYUK Andriy**(Queen Mary, Univ. of London) :__Eliciting Information from a committee__

**Monday 7 November 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**SCHLAG Karl**(University of Vienna) :__Decision Making in Uncertain and Changing Environments__

**Monday 7 November 2011 10:00-11:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**SKRETA Vasiliki**(NYU) :__Transparency and Commitment__

**Monday 31 October 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**SEREA Oana**(Université Paris 6) :__Differential games and Zubov's method__

**Monday 24 October 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**WAN Cheng**(Université Paris 6) :__Coalitions in nonatomic congestion games__

**Monday 17 October 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**HORNER Johannes**(Yale University) :__Stationary equilibria in continuons-time games with private monitoring__

**Monday 10 October 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**LACLAU Marie**(HEC Paris) :__Communication in repeated games played on a fixed network__

**Monday 3 October 2011 11:00-12:00**- Institut Henri Poincare - Salle 5, 314 ou 201
**OURY Marion**(Université de Cergy) :__Continuous implementation: a full characterization for finite environments__

**Monday 27 June 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**CELIK Gorkem**(ESSEC) :__Reciprocal relationships and mechanism design__

**Monday 20 June 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**ABDOU Joseph**(Université Paris 1 Panthéon-Sorbonne) :__Stability Index and Application to the Meet Game on a Lattice__

**Monday 6 June 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**LASAULCE Samson**(Supelec) :__Multiuser channels and games__

**Monday 30 May 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**TOMALA Tristan**(HEC) :__Belief-free communication equilibria in repeated games__

**Monday 23 May 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**SUDDERTH William**(University of Minnesota) :__Perfect Information Games with Upper Semicontinuous Payoffs__

**Monday 16 May 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**HERINGS Jean-Jaques**(Maastricht University) :__Stationary Equilibria in Stochastic Games: Structure, Selection, and Computation__

**Monday 9 May 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**TERCIEUX Olivier**(PSE) :__Robust Equilibria in Sequential Games under Almost Common belief__

**Monday 2 May 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**BLUME Andreas**(University of Pittsburgh) :__Language Barriers__**Co-auteur(s) : Oliver Board**- AbstractDifferent people use language in different ways. Private information about language competence can be used to re ect the idea that language is imperfectly shared. In optimal equilibria of common interest games there will generally be some benefit from communication with an imperfectly shared language, but the efficiency losses from private information about language competence in excess of those from limited competence itself may be significant. In optimal equilibria of common-interest sender-receiver games, private information about language competence distorts and drives a wedge between the indicative meanings of messages (the decision-relevant information indicated by those messages) and their imperative meanings (the actions induced by those messages). Indicative meanings are distorted because information about decision relevant information becomes confounded with information about the sender's language competence. Imperative meanings of messages become distorted because of the uncertain ability of the receiver to decode them. We show that distortions of meanings persist with higher-order failures of knowledge of language competence. In a richer class of games, where both senders and receivers move at the action stage and where payoffs violate a self-signaling condition, these distortions may result in complete communication failure for any finite-order knowledge of language competence.
- Full text [pdf]

**Monday 4 April 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**FAURE Mathieu**(Institut de mathématiques de Neuchâtel) :__Stochastic Approximations, Differential Inclusions and consistency in games__

**Monday 28 March 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**MARUTA Toshimasa**(Nihon University) :__Stochastically Stable Equilibria in n-person Binary Coordination Games__

**Monday 21 March 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**RÜDIGER Jesper**(Universidad Carlos III) :__Biased Information Transmission__

**Monday 14 March 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**JEHIEL Philippe**(PSE) :__Reputation with Analogical Reasoning__

**Monday 7 March 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**SABOURIAN Hamid**(University of Cambridge ) :__Repeated Implementation__

**Monday 28 February 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**YOUNG Peyton**(University of Oxford) :__Efficiency and Equilibrium in Trial and Error Learning__

**Monday 7 February 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**LESLIE David**(University of Bristol) :__Controlled learning in games__

**Monday 31 January 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**BICH Philippe**(Université Paris 1) :__Relaxed Nash Equilibria of Discontinuous Games__

**Monday 24 January 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**SOLAN Eilon**(Tel Aviv University) :__Des jeux d'arrêt en temps continu__

**Monday 17 January 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**MATHIS Jérôme**(TSE and University of Paris 8) :__Entrusting Decision Making to Experts__

**Monday 10 January 2011 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**HALPERN Joe**(Cornell University) :__Beyond Nash Equilibrium: Solution Concepts for the 21st Century__

**Monday 13 December 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**HAFER Catherine**(New York University) :__Institutions for Debate__**Co-auteur(s) : Dimitri Landa**

**Monday 6 December 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**EHUD Kalai**(Northwestern University) :__Stability in large Games with Heterogeneouns Players__

**Monday 29 November 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**FLESCH Janos**(Maastricht University) :__Strategic disclosure of random variables__

**Monday 22 November 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**WEIBULL Jorgen**(Stockholm School of Economics) :__Robustness to Strategic Uncertainty__

**Monday 15 November 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**RITZBERGER Klaus**(University of Vienna) :__Applications of Index Theory in Nash Equilibrium refinements__

**Monday 8 November 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**CRESSMAN Ross**(Wilfried Laurier University) :__Game Experiments on Cooperation through Punishment or Reward__

**Monday 25 October 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**HEIFETZ Aviad**(Open University of Israel) :__Comprehensive Rationalizability__

**Monday 18 October 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**LAMBERT-MOGILIANSKY Ariane**(PSE) :__Games with Type Inderteminate Players: Strategic Manipulation of Preferences__

**Monday 11 October 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**BATTIGALLI PierPaolo**(University of Bocconi) :__Strategy and Interactive Beliefs in Dynamic Games__

**Monday 4 October 2010 11:00-12:00**- Institute Henri Poicaré - Salle 314 ou 201
**SOSIC Greys**(University of Southern California) :__Stable Group Purchasing Organizations__

**Monday 28 June 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**KOESSLER Frederic**(PSE-CNRS) :__Using or Hiding Private Information? An Experimental Study of Zero-Sum Repeated Games with Incomplete Information__

**Monday 14 June 2010 11:00-12:00**- Institut Henri Poincare - Salle 314 ou 201
**RENOU Ludovic**(Univ. Leicester) :__Ordients: optimizations and comparative statics without utility function__

**Monday 7 June 2010 11:20-12:20**- Institut Henri Poincare - Salle 314 ou 201
**DZIUDA Wioletta**(Northwestern University) :__Ongoing Negotiation with Endogenous Status Quo__

**Monday 7 June 2010 10:00-11:00**- Institut Henri Poincare - Salle 314 ou 201
**AMIR Rabah**(Univ. Arizona) :__Discounted stochastic games with strategic complementarities.__

**Monday 17 May 2010 11:00-12:00**- Institut Henri Poincare Salle 314 ou 201
**DHILLON Amrita**(Warwick University) :__Corporate Control and Multiple Large shareholders__

**Monday 10 May 2010 11:00-12:00**- Institut Henri Poincaré - Salle 314 ou 201
**TAKAHASHI Satoru**(Princeton University) :__Recursive Methods in Discounted Stochastic Games: An Algorithm for delta ?1 and a Folk Theorem__

**Monday 3 May 2010 11:00-12:00**- IHP - Salle 314 ou 201
**KALAI Ehud**(Northwestern University) :__Engineering Cooperation in Two Player Strategic Games__

**Monday 12 April 2010 11:00-12:00**- Institut Henri Poincare
**GENSBITTEL Fabien**(Université Paris 1) :__Asymptotic behavior of repeated games with incomplete information and a linear payoff__

**Monday 29 March 2010 11:00-12:00**- Institut Henri Poincare
**SAMUELSON Larry**(Yale University) :__Pricing in Matching Markets.__

**Monday 22 March 2010 11:00-12:00**- Institut Henri Poincare
**ARIELI Itai**(Hebrew University of Jerusalem) :__Infinite sequential games with incomplete information.__

**Monday 15 March 2010 11:00-12:00**- Institut Henri Poincare
**VIDA Peter**(University of Vienna) :__Bidder-Optimal Signal Structure in a First Price Auction.__

**0000**- Voluntary confinement
**with Dominique Baril-Tremblay and Lucie Ménager**

**0000****MERTIKOPOULOS Panayotis**:__No-Regret Learning in Games__- AbstractAbstract: In many cases of practical interest, the players of a repeated game may not know the structure of the game being played - simply think of commuters driving to work every day, ignorant of the number of commuters at each part of the road. In such cases, it is often assumed that players follow a no-regret procedure, i.e. an updating policiy that provably minimizes each player's individual regret against any possible play of their opponents. This talk focuses on the following question: does the sequence of play induced by a no-regret learning process converge to an equilibrium of the underlying stage game? I will present some recent contributions to this question (in both finite and continuous games), and I will discuss the impact of the feedback available to the players.