Associate Professor (with tenure)
Department of Economics, Ecole Polytechnique
Fields:Microeconomic Theory, Game Theory, Information Economics, Political Economics.
Interim Bayesian Persuasion: First Steps,
This paper makes a first attempt at building a theory of interim Bayesian persuasion. I work in a minimalist model where a low or high type sender seeks validation from a receiver who is willing to validate high types exclusively. After learning her type, the sender chooses a complete conditional information structure for the receiver from a possibly restricted feasible set. I suggest a solution to this game that takes into account the signaling potential of the sender's choice.
American Economic Review: Papers & Proceedings, 2014, 104, 5.
Certifiable Pre-Play Communication: Full Disclosure
This article asks when communication with certifiable information leads to complete information revelation. We consider Bayesian games augmented by a pre-play communication phase in which announcements are made publicly. We first characterize the augmented games in which there exists a fully revealing sequential equilibrium with extremal beliefs (i.e., any deviation is attributed to a single type of the deviator). Next, we define a class of games for which existence of a fully revealing equilibrium is equivalent to a richness property of the evidence structure. This characterization enables us to provide different sets of sufficient conditions for full information disclosure that encompass and extend all known results in the literature, and are easily applicable. We use these conditions to obtain new insights in persuasion games with multidimensional types, games with strategic complementarities, and voting with deliberation.
with Jeanne Hagenbach and Frederic Koessler, Econometrica, 2014, 82, 3, 1093-1131.
Choosing Choices: Agenda Selection with Uncertain Issues
We study selection rules: voting procedures used by committees to choose whether to place an issue on their agenda. At the selection stage of the model, committee members are uncertain about their final preferences. They only have some private information about these preferences. We show that voters become more conservative when the selection rule itself becomes more conservative. The decision rule has the opposite effect. We compare these voting procedures to the designation of an agenda setter among the committee, and to a utilitarian social planner with all the ex interim private information.
with Raphael Godefroy, Econometrica, 2013, 81, 1, 221-253.
A Note on the Tight Simplification of Mechanisms,
Paul Milgrom (2010) proposes to simplify mechanisms by restricting their message space. When doing so, it is important not to create new equilibria. A weakly tight simplification is one that does not create new Nash equilibria, a tight simplification is one that does not create new ε-Nash equilibria. This note offers characterizations of tightness. When the preference domain is that of continuous utility functions on the outcome space, the two notions are equivalent, and are also equivalent to the outcome closure property of Milgrom (2008).
Economics Letters, 2011.
A Proof of Blackwell's Theorem,
This note gives a new proof of Blackwell's celebrated result.
The result is a bit stronger than the classical version since the action set and the prior are fixed,
and only the utility of the decision maker varies. I show directly that a decision maker has access to a
larger set of joint distributions over actions and states of the world if and only if her information improves
in the garbling order.
Communication with Evidence in the Lab,
We study communication with evidence in a collection of sender-receiver games in the lab. We find important differences between games with cyclic and acyclic masquerade relations. Overall, receivers take evidence into account and perform better in acyclic games, and with more precise messages. In acyclic games, they tend to be skeptical about vague messages, and more so over time. Sender types whose interests are aligned with those of the receiver fully disclose in all games, and sender types whose interests are not aligned with those of the receiver tend to use vague messages. When partially disclosing, senders tend to use weakly dominated strategies.
Jeanne Hagenbach, 2015.
Altruism in Networks,
We provide the first analysis of altruism in networks. Agents are embedded in
a fixed network and care about the well-being of their network neighbors. Depending on
incomes, they may provide financial support to their poorer friends. We study the Nash
equilibria of the resulting game of transfers. We show that equilibria maximize a concave
potential function. We establish existence, uniqueness of equilibrium consumption and
generic uniqueness of equilibrium transfers. We characterize the geometry of the network
of transfers and highlight the key role played by transfer intermediaries. We then study
comparative statics. A positive income shock to an individual benefits all. For small changes
in incomes, agents in a component of the network of transfers act as if they were organized
in an income-pooling community. A decrease in income inequality or expansion of the
altruistic network may increase consumption inequality.
Renaud Bourlès and
Yann Bramoullé, 2016. Revision requested at Econometrica.
Evidence Based Mechanisms,
This paper studies implementation with privately informed agents who can produce evidence. We define evidence based mechanisms as a class of mechanisms such that the designer's contingent plan of action is always consistent with available evidence. We characterize the social choice functions that can be straightforwardly implemented by such mechanisms. Our conditions imply that any social choice function that can be implemented with transfers and no evidence under quasilinear preferences can also be implemented with evidence and no transfers. If the agents have private values, it is possible to ex post implement the efficient social choice function with transfers that satisfy individual rationality and budget balance. With interdependent valuations, it is possible to implement the efficient outcome with transfers that satisfy individual rationality and budget balance in single-object auction and bilateral trade environments.
Frederic Koessler, 2015. Revision requested at Journal of Economic Theory.
Complicating to Persuade?,
This paper addresses a common criticism of certification processes: that they simultaneously generate excessive complexity, insufficient scrutiny and high rates of undue validation. We build a model of persuasion in which low and high types pool on their choice of complexity. A natural criterion based on forward induction selects the high-type optimal pooling equilibrium.When the receiver prefers rejection ex ante, the sender simplifies her report. When the receiver prefers validation ex ante, however, more complexity makes the receiver less selective, and we provide sufficient conditions that lead to complexity inflation in equilibrium.
with Delphine Prady, 2012.
Competing with Equivocal Information,
This paper studies strategic disclosure between multiple senders and a single receiver. The senders are competing for prizes awarded by the receiver. They decide whether to disclose a piece of information that is both verifiable and equivocal (it can influence the receiver both ways). Then the standard unraveling argument breaks down: if the commonly known probability that her information is favorable is sufficiently high, a single sender never discloses. Competition restores full disclosure only if some of the senders are sufficiently unlikely to have favorable information. When the senders are uncertain about each other's strength, however, all symmetric equilibria approach full disclosure as the number of candidates increases.
Robust Evidence Based Implementation, in preparation.
Evidence Based Matching, with Olivier Tercieux, in preparation.