Le séminaire se tient le lundi de 11h à midi, en général en salle 01 (rez-de-chaussée)

au Centre Emile Borel de l'Institut Henri Poincaré,

11 rue Pierre et Marie Curie, Paris 5ème. Plan

11 rue Pierre et Marie Curie, Paris 5ème. Plan

**Février 2017 - Séminaires**

**Lundi 6 mars****Takuro Yamashita****(TSE)***(Non)linear splitting problem: an attempt*

- Abstract: We consider a planner's problem of splitting a continuum of agents (e.g., students) with one-dimensional heterogeneous characteristic (e.g., ability) to finitely many groups (e.g., schools) to maximize the planner's objective (e.g., total attainment). Certain constraints may be imposed on the number of groups, each group's size, and monotonicity of assignment. An agent in a group enjoys externality from the other agents in the group (e.g., peer effects) summarized by the average characteristics, and in this sense, splitting is a nontrivial problem. First, under a mild condition on the environment, the optimal splitting is characterized in the ``linear'' environment, that is, in the environment where the planner's objective is affine in the agents' characteristics. Second, the optimal splitting is characterized in some ``nonlinear'' cases under additional assumptions of separability and mononicity in convexity

**Lundi 13 mars****ATTENTION SEMINAIRE DOUBLE !!**

**10h - 11h Thomas****Lidbetter****(Rutgers Business School)***Mining coal or finding terrorists: the expanding search paradigm (joint with S. Alpern).*The natural paradigm for searching a graph is a walk: that is, a sequence of edges, each one of which must be adjacent to the one before it. Here we consider an alternative paradigm called “expanding search”, where each edge in the sequence may be adjacent to any previous edge. This is appropriate for situations such as mining for coal, when the cost of moving miners or equipment to a point already reached is negligible compared to the cost of digging. It can also model a team of searchers, successively splitting into smaller groups. We consider zero-sum search games played on a graph with edge weights corresponding to traversal times. A (time maximizing) player hides one or more objects on the graph and a (time minimizing) player chooses an expanding search of the graph; the payoff is the time to capture all the objects. We give some solutions of the game in some cases and highlight some open problems.*Abstract:*

**11h15 - 12h15 Tobias Harks****(Augsburg University)***Polymatroid optimization and equilibrium computation (joint with M. Klimm and B. Peis)*The talk will discuss the sensitivity of optimal solutions of convex separable optimization problems over an integral polymatroid base polytope with respect to parameters determining both the cost of each element and the polytope. Under convexity and a regularity assumption on the functional dependency of the cost function with respect to the parameters, it is shown show that reoptimization after a change in parameters can be done by elementary local operations. I will show that these sensitivity results can be applied to a new class of non-cooperative games played on integral polymatroid base polytopes in order to compute pure Nash equilibria.*Abstract:*

**Lundi 20 mars****Francis Bloch****(PSE and Paris 1)***Bundling in simple games (joint with K. Chatterjee).*- Abstract: This paper studies the incentives to bundle issues in the coalitional bargaining game of Baron and Ferejohn (1989). Players endogenously choose whether to make offers on issue 1, issue 2 or a joint offer on the two issues. The winning coalitions may be different on the two issues. We characterize the pairs of simple games for which bundling does not affect the limit equilibrium payoffs. We provide a partial characterization of the pairs of simple games for which all agents strictly prefer bundling to making separate offers and examples of situations where all players strictly prefer to make separate offers on the two issues.

**Lundi 27 mars**__John Levy__(University of Glasgow)*Measurable selections on countable Borel equivalence relations and applications to games (joint with Z. Hellman)*- Abstract: We prove a measurable selection theorem allowing one to obtain global existence results from local ones on smooth countable Borel equivalence relations. These results allow us to naturally formulate problems such as existence of equilibrium in Bayesian games with purely atomic beliefs transitions and to deduce existence under smoothness conditions of the common knowledge structure. Results on equilibria in some stochastic games and other phenomena are also presented.

**Lundi 3 Avril Vacances de Pâques****Lundi 10 Avril Vacances de Pâques****Lundi 17 Avril Lundi de Pâques**

**Lundi 20 mars****Saïd Hamadene****(Université du Maine)***Weak formulation of mean-field control and zero-sum game problems (joint with B.Djehiche)*- Abstract: We
deal with the weak formulation of the mean-field control
problem and the mean-field zero-sum differential game as
well. We show existence of an optimal control and a
saddle-point for respectively the control problem and
zero-sum differential game associated with payoff functionals
of mean-field type, under dynamics driven by weak solutions
of stochastic differential equations of mean-field type.

__Séminaire des Thésards__**(de 10h à 11h, même salle, sauf en cas de séminaire double)**

**Page web de Stefano Moretti recensant les événements de théorie des jeux à Paris : cliquer ici**