### Séminaires

# Lunch séminaire Théorie, Organisation et Marchés (TOM)

Ce séminaire est organisé par Marie Laclau.

Contact opérationnel : Violaine Tordeux

## Prochainement

**Jeudi 29 juin 2017 13:00-14:00**- salle R1-15, campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**BOUACIDA Elias**(PSE) :__Indifference or Indecision, an Experimental Investigation using Choice Correspondences__- RésuméAbstract. The completeness axiom is a staple in economics, despite its lack of both: 1. Normative appeal, as pointed by Aumann (1962); 2. Descriptive investigation, apart from two experiments using lotteries by Danan and Ziegelmeyer (2006) and Cettolin and Riedl (2016). In this paper, I am tackling the second question. I show how to elicit a choice correspondence -- in contrast to a choice function, as usually done in experiments -- in an incentive compatible way, while keeping the revealed preferences methodology. This allows the elicitation of -- some -- indifference and -- some -- indecision (aka incompleteness) in experiments using Eliaz and Ok (2006)'s characterization, which provides a lower bound on indecision. This procedure is applied to the choice between four incentivized tasks to be performed in the laboratory. I observe some indifference for a majority of subjects and some indecision for around a quarter of them.

## Archives

**Jeudi 22 juin 2017 13:00-14:00**- salle R1-11, campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**HE Yinghua**(Rice) :__Strategic Mistakes: Implications for Market Design Research__**Yeon-Koo Che (Columbia) and Georgy Artemov (Melbourne**- RésuméAbstract. A field data from Australian college admissions shows that a non-negligible fraction of applicants choose strategies (or rank-ordered lists) that are unambiguously dominated, but that the majority of these mistakes are payoff irrelevant. In keeping with this result, we develop a theory suggesting that the presence of such mistakes jeopardizes the identication method based on truthful reporting hypothesis under a (seemingly) strategy-proof mechanism, but leaves the method based on weaker stability condition relatively unscathed. Monte Carlo simulation further confirms this point and quantifies the differences between these two methods in the structural estimation of preference parameters and in a hypothetical counterfactual analysis.

**Jeudi 18 mai 2017 13:00-14:00**- salle R1-11, campus Jourdan, 48 boulevard Jourdan, Paris 14e
**PEJSACHOWICZ Leonardo**(Princeton) :__Breadth versus Depth.__- RésuméAbstract. We consider a fundamental trade-off in search: when choosing between multiple unknown alternatives, is it better to learn a little about all of them (breadth) or a lot about a single one (depth)? In choice settings where a distribution is exogenous, we find that breadth is optimal for ``small'' problems and that depth is optimal for ``large'' ones. But in IO settings, where firms endogenously choose distributions, we find breadth to be always optimal. Finally, we consider extensions to fat-tails and correlation, and find that in these extensions, breadth is superior.

**Jeudi 20 avril 2017 13:00-14:00**- campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**BASTIANELLO Lorenzo**(Paris 1) :__Target-based solutions for Nash bargaining__

**Jeudi 6 avril 2017 13:00-14:00**- salle F, bâtiment G, campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**BIRO Peter**( (Hungarian Academy of Science)) :__Stable Project Allocation under Distributional Constraints__**joint with Agoston and Szanto**- RésuméAbstract. In a two-sided matching market when agents on both sides have preferences the stability of the solution is typically the most important requirement. However, we may also face some distributional constraints with regard to the minimum number of assignees or the distribution of the assignees according to their types. These two kind of requirements can be challenging to reconcile in practice. Our research is motivated by two real applications, a project allocation problem and a workshop assignment problem, both involving some distributional constraints. We used integer programming techniques to nd reasonably good solutions with regard to the stability and the distributional constraints. Our approach can be useful in a variety of di erent applications, such as resident allocation with lower quotas, or controlled school choice.

**Jeudi 30 mars 2017 13:00-14:00**- Salle R1-11, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**STEPANOV Sergey**(Higher School of Economics ) :__Reputation and information aggregation.__

**Jeudi 23 mars 2017 13:00-14:00**- Salle R1-11, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**WOODWARD Kyle**(University of North Carolina ) :__Equilibrium and Approximation in Auction-Like Models__- RésuméI define auction-like models with continuum actions to satisfy a number of conditions which are met in common auction contexts, when action spaces are appropriately constrained. In these models, I prove that there exists a monotone pure-strategy Bayesian-Nash euqilibrium. The proof of equilibrium existence constructs equilibrium as a limit of equilibria of nearby discretized models, which implies that utility-relevant observable functions of actions are converging in probability to the continuum-action limit. The conditions defining auction- like models are intuitive: first, bidder utility cannot be adversely affected by small upward deviations; second, with small deviations bidders can guarantee themselves nearly the utility at a limit of strategies in the limit of the deviated strategies; third, if one bidder is discontinuously worse off in a limit of strategies, some other bidder is occasionally better off. Under mild additional conditions, the action space constraints are irrelevant, and the limiting strategies are an equilibrium in the unconstrained continuum-action model. I use these results to prove the existence of pure-strategy equilibria in divisible-good pay-as-bid auctions with private information, heterogeneous agents, and generic decreasing value functions. Equilibrium approximation implies that the distribution of observed allocations and seller revenue in discrete auctions may be close to the distribution of these outcomes predicted by the divisible-good model.

**Jeudi 16 mars 2017 13:00-14:00**- Salle R1-11, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**JEHIEL Philippe**( PSE) :__Investigation with forgetful liars__- RésuméAbstract: I consider environments in which an individual not telling the truth does not remember which lie he made and I propose modelling how such an individual forms a belief about his past lie using the apparatus of the analogy-based expectation equilibrium so that after performing a lie the individual considers that he lied according to the aggregate distribution of lie performed in equilibrium across all possible observations that the individual may possible make. I study the extent to which how asking subjects several times about their information and committing to harsh punishments in case of contradiction allows to elicit information and implement the first-best ouctome. Various extensions allowing for a mix of rational and forgetful liars are considered.

**Jeudi 9 mars 2017 13:00-14:00**- salle R1-11, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**GOMES RENATO**(TSE) :__Drip Prices and Missed Sales__**joint with TIROLE Jean**- RésuméAbstract: Firms often sell a basic good as well as ancillary ones. Hold-up concerns have led to regulations on ancillary good pricing such as price transparency and caps on the add-on price. The hold-up narrative, however, is an inaccurate description of many retail settings in which add-ons are offered below cost (e.g. free shipping), and of the infrequent card surcharging in countries where the “no-surcharge rule” was lifted. We argue that the key to unifying these conflicting narratives is the seller’s concern about losing sales on the basic good. When the ancillary good is self-supplied (or equivalently supplied by a competitive upstream ancillary-good industry) and consumers are well-informed about prices (attentive or repeat customers), the firm passes through the cost of the ancillary good to the consumer if the (endogenous) markup on the basic good is small, but absorbs partly or fully any ancillary good cost increase if this markup is high, so as not to run the risk of losing sales. The ancillary good is always sold below cost. When the ancillary good is provided by a supplier with market power, the latter has an incentive to jack up the intermediate price so as to benefit from the seller’s cost absorption strategy. We show that the optimal regulation is a price floor on the ancillary good, equal to the intermediate price. We also show that absent regulation, there is an overprovision of the ancillary good when the ancillary good is supplied by a two-sided platform. When consumers are initially unaware of the ancillary good price, the price of the basic good acts as a signal of the ancillary good price: A high price for the basic good makes the firm more wary of missed sales and thus reassures the consumer about the ancillary good price. We study the optimal regulation

**Jeudi 2 mars 2017 13:00-14:00**- salle DSS, bâtiment B, Campus Jourdan, 75014 paris
**TOMALA Tristan**(HEC Paris) :__Competitive Information Design. Work in progress.__**joint with Frédéric Koessler (PSE) and Marie Laclau (PSE).**- RésuméAbstract. We study games between n information designers, each of whom can perform a statistical experiment about a piece of information, the pieces being independent. They aim at persuading a decision-maker to take their most favorable action. For such games with discontinuous payoffs, we show that there exists a (sub-game perfect) equilibrium with either an infinite number of messages or randomization over finite statistical experiments. We characterize the equilibrium distributions of actions for rectangular games in which the optimization problem of the decision-maker is separable across designers. Rectangular games have a (sub-game perfect) equilibrium in pure strategies with a finite number of messages.

**Jeudi 2 février 2017 13:00-14:00****La séance a été annulée.****BOUACIDA Elias**(PSE) :__*__

**Jeudi 19 janvier 2017 13:00-14:00****TALLON Jean-Marc**(PSE) :__Asset Allocation and Trade under Heterogeneous Ambiguity Aversion__**with S. Mukerji and H. Ozsoylev**- RésuméAbstract: We seek to explore several financial puzzles in a single model, that departs from basic portfolio choice models only in that it accomodates ambiguity and ambiguity sensitve preferences. The three anomalies are (1) the asset allocation puzzle wich is the observation that professionnals' recommandations for portfolio holdings do not accord well with the mutual fund theorem, (2) departures from CAPM pricing in a systematic way and (3) large volume of trade after public annoucement of earnings. We propose a model where investors have smooth ambiguity preferences and asset returns have ambiguous means. We show that investors optimally hold portfolio with a different mix of risky assets, due to their heterogeneous ambiguity aversion. This heterogeneity also leads, in an equilibrium model, to trade upon the arrival of public information (about the dividends).

**Jeudi 12 janvier 2017 13:00-14:00****FLECKINGER Pierre**(Mines et PSE) :__Game of Frauds__**T. Lafay and C. Monnier**

**Jeudi 15 décembre 2016 13:00-14:00****COUANAU Quentin**(PSE) :__Cooperation versus competition under ambiguity aversion__- RésuméAbstract : We study a principal-agent model with two agents and two positively correlated tasks. We assume that agents face ambiguity (or knightian uncertainty) regarding the tasks and are averse to ambiguity. Our focus is on whether the presence of ambiguity aversion favors cooperation or competition between agents, as compared to risk aversion. We show that the effect of ambiguity is twofold. It lowers the power of incentives making agents' wages less sensible to performance, while it increases significantly the cost of implementing relative incentives. As a consequence, the principal does not necessarily choose relative incentives, even in situations where they would always be optimal under risk. Allowing for agents to cooperate, we show that ambiguity aversion favors cooperation between agents while risk aversion favors competition.

**Jeudi 8 décembre 2016 12:30-13:30**- Salle F, Bât G
**HAGENBACH Jeanne**(CNRS, Ecole Polytechnique) :__Communication with Evidence in the Lab__**E. Perez-Richet**- RésuméWe study communication with evidence in the lab. Our experimental design involves a collection of sender-receiver games with various payoffs and permits partial disclosure. We use local and global properties of the sender's incentive graph to uncover behavioral regularities and explain performance across games. Sender types whose interests are aligned with those of the receiver fully disclose, while sender types whose interests are not aligned with those of the receiver remain silent or partially disclose. When partially disclosing senders mostly disclose favorable pieces of evidence and hide unfavorable ones. But the cognitive cost of partial disclosure, as measured by response times, is higher for both senders and receivers. Receivers take evidence into account and tend to be skeptical about vague messages in games whose graph is acyclic. They perform better in acyclic games, whereas senders perform better in cyclic games.

**Jeudi 1er décembre 2016 13:00-14:00**- Matching with Ownership
- RésuméAbstract : We consider a hybrid model at the intersection between the standard two-sided matching market as proposed by Gale and Shapley (1962) and a housing market as proposed by Shapley and Scarf (1974). Two types of agents have to be matched to a common side of objects. Agents of one type have preferences that depend on the object they are matched to but also which agent of the other type is matched to this object. To investigate the link with the two-sided matching literature, we define a natural concept of ownership structure that determines for each possible triplet of match, which agent owns the object. We then define a pairwise stability property of matchings with respect to an ownership structure i.e. where only an owner could ask another agent to join his current object. We first show that there are ownerships structures for which no such matching exists. However, we show that it exists for one-sided ownership structures i.e. when agents of one type are always the owners. In this framework, we show that contrary to a standard two-sided matching market, there may not be any core matching even if stable matchings exist. The existence is restored if we assume that agents of the side always owning the objects have lexicographic or separable preferences. To investigate the link with a housing market model, we define an initial allocation of the objects to one agent and define the standard notion of core in this framework. Even with one sided initial allocation, we show that the latter may also be empty. However, with such initial allocations, we show that there always exists a Pareto-efficient matching that cannot be blocked by coalitions of size two.

**Jeudi 17 novembre 2016 13:00-14:00****HERINGS Jean-Jacques**(Maastricht University) :__Equilibrium and Matching under Price Controls__- RésuméThe paper considers a one-to-one matching with contracts model in the presence of price controls. This set-up contains two important streams in the matching litera- ture, those with and those without monetary transfers, as special cases and allows for intermediate cases with some restrictions on the monetary transfers that are feasible. An adjustment process that ends with a stable outcome is presented, thereby prov- ing the existence of stable outcomes. The process contains the deferred acceptance algorithm of Gale and Shapley (1962) and the approximate auction mechanism of Demange, Gale, and Sotomayor (1986) as special cases. The paper presents a no- tion of competitive equilibrium, called Dreze equilibrium, for this class of models, an extension of the concept as developed by Dreze (1975) for economies with divisible commodities subject to price controls. It is shown that Dreze equilibrium allocations are equivalent to allocations induced by stable outcomes. One implication is the ex- istence of Dreze equilibria. Another implication is the equivalence of a competitive equilibrium concept and the concept of stable outcomes that is valid with and with- out monetary transfers as well as when monetary transfers are limited.
- Texte intégral [pdf]

**Jeudi 10 novembre 2016 13:00-14:00****SALAMANCA Andrés**(TSE) :__The value of mediated communication__- RésuméAbstract: Kamenica and Gentzkow (2011) consider a model in which a sender chooses a public communication device for signaling his information to an uninformed receiver, who then takes an action that aects the welfare of both individuals. In their model, the sender is fully committed to truthfully communicate the signal to the receiver, so that they abstract from incentive compatibility issues. By considering mediated communication, we provide an analytical framework overcoming this overly restrictive assumption. Specically, we are able to characterize incentive constraints by a set of linear inequalities, which allows to formulate the sender's problem as a linear programming problem. As a result, we can use an alternative geometric approach based on duality theory to transform the sender's problem into a simplied problem without incentive constraints that can be solved using concavication

**Jeudi 3 novembre 2016 13:00-14:00****ISPANO Alessandro**(University Cergy-Pontoise) :__Competitive pricing and quality disclosure to cursed consumers__- RésuméAbstract: We study the disclosure decision and price-setting behavior of competing firms in the presence of cursed consumers, who fail to be sufficiently skeptical about a firm's quality upon observing non-disclosure of quality-relevant information. We show that neither competition nor the presence of sophisticated consumers necessarily offer protection to cursed consumers. Exploitation arises if markets are vertically differentiated, if there are many sophisticated consumers, and if it is more likely ex ante that product quality is high. Information campaigns that seek to educate consumers may encourage exploitation and decrease social welfare. Mandatory disclosure laws restore efficiency, but at the cost of redistributing rents from consumers to firms. Our simple model delivers a rich set of positive results, captures important markets, like those for food and consumer finance, and speaks to several recent policy initiatives aimed at consumer protection.

**Jeudi 13 octobre 2016 12:30-13:45****LAMBERT-MOGILIANSKY Ariane**(PSE) :__Phishing for phools - Dynamic consistency under non-classical uncertainty__**V.I. Danilov and V. Vergopoulos**- RésuméIn this paper we develop an expected utility theory in the context of non-classical(quantum) uncertainty. We replace the classical state space with a Hilbert space which allows introducing the concept of quantum lottery. Within that framework we formulate sufficient and necessary axioms in terms of choice behavior and establish a representation theorem. We show that demanding the consistency of choice behavior conditional on new information is equivalent with the von Neuman-Luder postulate applied to beliefs. As a consequent we find that rational choice behavior can be consistent with non-commutativity in updating. Finally, we discuss the value of our results for behavioral economics

**Jeudi 6 octobre 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**DOSIS Anastasios**:__*__

**Jeudi 29 septembre 2016 12:45-13:45****REDLICKI Bartosz**(U of Cambridge) :__Spreading Disinformation.__- RésuméIt is a common tactic, e.g., for political parties, to manipulate information without any official verification and then spread it by word of mouth. I develop a theoretical model which combines elements of Bayesian persuasion and cheap talk. An individual, called “manipulator”, manipulates information by designing an information policy, which is modelled by Bayesian persuasion. The information then diffuses via a chain of cheap talk communication in a population of agents with heterogeneous preferences. The manipulator’s objective is to spread disinformation so that as many agents as possible take high actions. He needs to take into account that his information policy can affect the agents’ own incentives to manipulate information during its diffusion. The manipulator’s optimal information policy has a high degree of manipulation if the majority of agents have a large upward bias. On the other hand, he may set a lower degree of manipulation in order to make the information more credible to agents with no upward bias or to improve information diffusion between agents with different preferences.

**Jeudi 23 juin 2016 12:45-13:45****GABAIX Xavier**(NYU Stern) :__tba__

**Jeudi 16 juin 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**SEROR Avner**(PSE) :__A Theory on the Evolution of Civic Culture and Political Cycles__- RésuméWe argue in this paper that political cycles in democracies impede the diffusion of civic values, thereby contributing to a persistent political instability. Indeed, we build a theory on the evolution of political cycles under repeated majoritarian elections whenever civic values are transmitted inter-generationally. We first establish that cycles in public expenditures result from asymmetric information on incumbents' civic attitude. We then show that recurrent suboptimal increases in the public provision weight on average less on the cultural transmission strategies of the agents with low civic values. This is because the latter have on average a lower propensity to contribute to the public provision, and consequently suffer less from the higher taxes induced by the cycles. Thus, cycles of a sufficiently high magnitude persist because they create weak civic majorities in which informed voters are not majoritarian. At the opposite, low magnitude cycles may not impede the formation of a majority of informed civic voters. The preceding cycles are then transitory and civic norms consolidate once they disappear. Finally, we suggest that the composition of the cycling expenditures matters as well in explaining the diffusion of civic values.

**Jeudi 9 juin 2016**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**ZACCOUR Georges**(HEC Montréal) :__TBA__

**Jeudi 2 juin 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**BRETON Michèle**(HEC Montréal) :__Mergers in Nonrenewable Resource Oligopolies and Environmental Policies: A green paradox__- RésuméWe examine the profitability of horizontal mergers within nonrenewable resource industries, which account for a large proportion of merger activites worldwide. We focus on the case of a tripoly where each firm owns a private resource stock of the resource, and firms compete in quantities. We show that a merger is profitable when the resource stock owned by each firm is small enough. We also consider an endogenous merger process and show that monopolization is profitable when the resource stock of each firm is small enough. In the case where pollution is generated by the industry's activity, we show that an environmental policy that increases firms' production cost or reduces the price received by firms can deter a merger and therefore result in larger industry emissions than under a laisser-faire scenario. The impact of such an environmental policy on merger profitability generally depends on the level of the resource stocks. When the stocks are large enough, a tax on extraction reduces the losses from a horizontal merger.

**Jeudi 26 mai 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**KOESSLER Frédéric**(PSE and CNRS) :__tba__

**Jeudi 19 mai 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**MONTERO Juan Pablo**(PUC-Chile) :__Bundled Discounts and Foreclosure in Wholesale Markets__**Enrique Ide**- RésuméCan a multi-product firm offer bundled-discounts to foreclose a more efficient single-product supplier? We show that the degree of downstream competition is key. Bundled-discounts are successful in depriving single-product rivals of scale economies only to the extent that buyers are disorganized and their valuations heterogeneous. This holds when suppliers deal directly with final consumers, or when they sell to retailers that compete intensely in downstream markets, but it is lost in the case of retail monopolies. These results are robust to alternative timing assumptions and different ways to model scale economies.

**Jeudi 12 mai 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**RITZBERGER Klaus**(IAS Vienna) :__The Curse of Poverty and the Blessings of Wealth__- RésuméIf productivity in a society is low, then the only equilibrium involves inefficiently selfish (autarkic) behavior. If productivity is sufficiently high, then there are several equilibria that realize substantial welfare gains through reciprocal behavior. Equilibria for productive societies are distinguished by how they treat the wealth distribution. While conservative societies preserve the distribution, egalitarian behavior further improves welfare by transfers. Yet, both conservative and egalitarian (productive) societies exclude the poorest, even though that involves a welfare loss. So, there are a social and an individual poverty trap. The first is technological, the second behavioral.

**Jeudi 14 avril 2016 12:45-13:45****ENACHE Andreea**(EUI, Florence) :__TBA__

**Jeudi 7 avril 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**VARDAR Boris**:__TBA__

**Jeudi 31 mars 2016 12:45-13:45****La séance a été annulée.****LAMBERT-MOGILIANSKY Ariane**(PSE) :__Dynamic consistency of expected utility under non-classical(quantum) uncertainty__**Danilov V.I. and V. Vergopoulos**- RésuméIn this paper we develop an expected utility theory in the context of non-classical(quantum) uncertainty. We replace the classical state space with a Hilbert space which allows introducing the concept of quantum lottery. Within that framework we formulate sufficient and necessary axioms in terms of choice behavior and establish a representation theorem. We show that demanding the consistency of choice behavior conditional on new information is equivalent with the von Neuman-Luder postulate applied to beliefs. As a consequent we find that rational choice behavior can be consistent with non-commutativity in updating. Finally, we discuss the value of our results for behavioral economics.

**Jeudi 24 mars 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**BLOCH Francis**(pse paris1) :__The formation of partnerships in social networks__**Bhaskar Dutta, Stephane Robin et Min Zhu**- RésuméThis paper analyzes the formation of partnerships in social networks. Agents randomly request favors and turn to their neighbors to form a partnership where they commit to provide the favor when requested. If favors are costly, agents have an incentive to delay the formation of the partnership. In that case, we show that for any initial social network, the unique Markov Perfect equilibrium results in the formation of the maximum number of partnerships when players become infinitely patient. If favors provide benefits, agents rush to form partnerships at the cost of disconnecting other agents and the only perfect initial networks for which the maximum number of partnerships are formed are the complete and complete bipartite networks. The theoretical model is tested in the lab. Experimental results show that a large fraction of the subjects (75\%) play according to their subgame perfect equilibrium strategy and reveals that the efficient maximum matching is formed over 78\% of the times. When subjects deviate from their best responses, they accept to form partnerships too early. The incentive to accept when it is optimal to reject is positively correlated with subjects' risk aversion, and players employ simple heuristics -- like the presence of a captive partner -- to decide whether they should accept or reject the formation of a partnership.

**Jeudi 17 mars 2016 12:30-14:30**- Campus Jourdan, bâtiment E, rez-de-chaussée, salle 101
**MATHEVET Laurent**(NYU) :__Information Design: The Random Posterior Approach (1)__**GEEROLF François**(UCLA) :__Paretos from Production Functions (2)__- Résumé(1)Information affects behavior by affecting beliefs. Information design studies how to disclose information to a group of players to incentivize them to behave in a desired way. This paper is a theoretical investigation of information design, culminating with a representation theorem and a fundamental application of it. We adopt a random posterior perspective, viewing information design as belief manipulation rather than information disclosure. The representation theorem shows that it is as if the designer manipulated beliefs in a specific way, shaping the approach in games, as did Kamenica and Gentzkow (2011) in one-agent problems. The representation theorem can also be implemented in specific problems, for example in the beauty contest and multiple-agent problems. We focus on an application that we dub the Mother's Problem.

(joint with J. Perego and I. Taneva)

(2)This paper shows that Pareto distributions can arise from production functions rather than from the distribution of primitives. A version of Garicano (2000)’s knowledge-based production hierarchies microfounds such a production function. It generates under very limited assumptions on the distribution of primitives (here, agents’ skills), Pareto distributions for span of control of CEOs as well as intermediary managers, and in particular Zipf’s law for firm sizes when the number of layers of management becomes large. This breakdown of the aggregate firm size distribution receives important empirical support in the French matched employer-employee administrative data. This novel justification of Pareto distributions can shed a new light on why outcomes are often so out of proportion compared to underlying primitives. For example, it provides a framework to study the recent rise in top income inequality. The analysis also has striking implications on the literature on firm heterogeneity: Pareto distributions are in fact the benchmark distributions arising in the case of perfect homogeneity, while heterogeneity in primitives should instead be backed out in the deviations from Pareto distributions.

**Jeudi 10 mars 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**VENEL Xavier**(Paris 1 et PSE) :__Dynamical strategic interaction in social networks__- RésuméWe consider a dynamical model of influence with a set of non-strategic agents and two strategic agents. The non-strategic agents are organized in a fixed network describing how they influence each other. The strategic agents have opposite opinion and try to drive the opinion of the society by targeting key-players in the network. We formulate this problem as a two-player zero-sum stochastic games allowing the strategic agents to change their target at every stage of the game. We prove the existence of the uniform value: if the player are sufficiently patient, both players can guarantee the same mean-average opinion without knowing the exact discount factor.

**Jeudi 18 février 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**FAVART Thomas**(PSE) :__Collusion in Capacity Under Irreversible Investment__- RésuméThis work studies the possibility of collusion under irreversible investment in production capacity. The irreversibility of investment has two effects. It reduces the profitability of short run deviation, as the deviating firm has to invest in order to increase its capacity. It also creates a long run effect. Once the deviating firm has invested, it is committed to its new capacity. The deviation may thus lead to a preemption of the punishing firm. When the firms become more patient, the short run profitability of a deviation increases whereas the long run profitability is reduced. When the second effect dominates, collusion is harder to sustain for more patient firm. This contrasts with the literature on collusion. Finally, this work shows that the smallest firm has the most incentives to deviate.

**Jeudi 11 février 2016 12:45-13:45****HERNANDEZ Penelope**(Valencia) :__Conflict and segregation in networks: individual preferences and social influence__- RésuméWe examine the interplay between a person's individual preference and the social influence others exert. We provide a model of network relationships with conflicting preferences, where individuals are better off coordinating with those around them, but not all prefer the same action. We test our model in an experiment, varying the level of conflicting preferences between individuals. Our findings suggest that preferences are more salient than social influence, under conflicting preferences: subjects relate mainly with others who prefer the same. This leads to two undesirable outcomes: network segregation and social inefficiency. The same force that helps people individually hurts society.

**Jeudi 4 février 2016 12:45-13:45****LAMY Laurent**:__On the benefits of set-asides__**Philippe Jehiel**

**Jeudi 28 janvier 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**NAX Heinrich**:__A behavioral study of « noise » in coordination games__**Michael Mäs**- Résumé‘Noise’ in this study, in the sense of evolutionary game theory, refers to deviations from prevailing behavioral rules. Analyzing data from a laboratory experiment on coordination in networks, we tested ‘what kind of noise’ is supported by behavioral evidence. This empirical analysis complements a growing theoretical literature on ‘how noise matters’ for equilibrium selection. We find that the vast majority of decisions (96% ) constitute myopic best responses, but deviations continue to occur with probabilities that are sensitive to their costs, that is, less frequent when implying larger payoff losses relative to the myopic best response. In addition, deviation rates vary with patterns of realized payoffs that are related to trial-and-error behavior. While there is little evidence that deviations are clustered in time or space, there is evidence of individual heterogeneity.

**Jeudi 21 janvier 2016 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**RIVERA Thomas**:__Incentives and the Structure of Communication__- RésuméThis paper analyzes the incentives that arise within an organization when communication is restricted to a particular network structure (e.g., a hierarchy). We show that restricting communication between the principal and agents may create incentives for the agents to misbehave when transmitting information and tasks throughout the organization. Such incentives can render the principal's most preferred outcome infeasible and therefore introduces a trade off between the cost of communication borne by the principal and the benefit of curbing incentives to deviate induced by the communication structure. To remedy this issue, we provide necessary and sufficient conditions on the topology of the network of communication such that restricting communication to a particular network does not restrict the set of outcomes that the principal could otherwise achieve. In this sense, we show that for any underlying incentives and any outcome available when communication is unrestricted, there exists a (finite) communication scheme restricted to a particular network that implements this outcome (i.e., does not induce agents to misbehave in the communication phase) if and only if that network satisfies our conditions

**Jeudi 14 janvier 2016 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 10
**BEHRINGER Stefan**:__Public Good Provision with many Agents: The k-success technology__**Yukio Koriyama, Ecole Polytechnique**- RésuméIn this paper, we consider a class of public good provision problems in which the production function takes the form of k-success technology, an extension of the direct provision technology considered in Behringer (2013). These models are suitable to describe the free-rider problems in which there are a large number of agents who are both users and beneficiaries of a public good at the same time, e.g. open-source software or social networks. We provide results on asymptotic efficiency which connect a negative result of Mailath and Postlewaite (1990) and a positive result of Hellwig (2003), as well as a set of simple examples which allow us welfare comparison with the standard technologies.
- Texte intégral [pdf]

**Jeudi 17 décembre 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**LE CHAPELAIN Alexis**(Science-po) :__*__

**Jeudi 10 décembre 2015 12:45-13:45****RAI Birendra**:__Preference Domains and Bilateral Bargaining: An Experiment__- RésuméTheoretical results and experimental findings from competitive settings suggest that agents with other-regarding preferences (ORP) often behave as if they have self-regarding preferences. We say an institution (game form) is `robust' wrt ORP if the above holds. We experimentally explore whether and when such robustness arises in non-competitive environments using a series of ultimatum games where proposer's monetary payoff upon rejection varies. The data provides some insights into when and why robustness holds wrt which type of ORP.

**Jeudi 26 novembre 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 10
**IARIA Alessandro**(CREST) :__Estimating Demand Parameters with Choice Set Misspecification__- RésuméWe describe methods to estimate demand parameters in the presence of choice set misspecification due to unobserved individual choice sets. We show that a consumer’s probability of making a choice from her true choice set can be written as the probability she makes the same choice from a universal choice set, an assumption commonly made in the empirical literature, less a bias term capturing the probability that she would choose any of the elements in her true choice set. We show how to estimate models that avoid this bias under Logit demand using “sufficient sets,” instances where (observationally identical) individuals make at least two choices from the same unobserved choice set. Examples of sufficient sets include a variation of the Fixed Effect Logit approach due to Chamberlain (1980), using observed individual-specific purchase histories, and assuming common unobserved choice sets across individual purchases in a given retailer and time period. We illustrate these ideas using household-level scanner data exploiting variation in choice sets based on the introduction of a new product variety and heterogeneous product offerings across stores in the market for ketchup in the UK. Our results show that accounting for choice set misspecification is critical for accurately estimating own- and cross-price elasticities of demand.

**Jeudi 19 novembre 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MARFAN Manuel**(PSE) :__Multidimensional Delegation__- RésuméWe study a principal agent model without transferable utility in which both the agent's private information and the decision to be made is multidimensional. We study properties of the optimal delegation set, that is, the set of actions that will be taken on equilibrium, and compare with the single dimensional case. Finally, we study the use of "constant caps" as seen in Frankel (2014), and obtain necessary and sufficient conditions for their optimality.

**Jeudi 12 novembre 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**DOSIS Anastasios**(Essec) :__Nash Equilibrium in? Competitive Markets with Adverse Selection__- RésuméWe generalise the results of Rothschild and Stiglitz (1976). We define the generalised Rothschild - Stiglitz allocation (RSA), and we show that, in every possible market, if the RSA is efficient, it is also a pure Nash equilibrium. In markets in which the RSA is not efficient, we specify a broader than Rothschild and Stiglitz (1976) class of environments in which no pure Nash equilibrium exists.

**Jeudi 5 novembre 2015 12:45-13:45**- Campus Jourdan, bâtiment B, 1er étage, salle CMH
**SZECH Nora**(Kalsruhe) :__*__

**Jeudi 29 octobre 2015 12:45-13:45**- Campus Jourdan, bâtiment B, 1er étage, salle CMH
**HARRINGTON JOE**(Warton Business School) :__A Theory of Collusion with Partial Mutual Understanding__- RésuméUnlawful collusion is when Örms have a mutual understanding to coordinate their behavior for the purpose of achieving a supracompetitive outcome. Given the legal focus on mutual beliefs, this paper initiates a research program to explore how much and what type of mutual beliefs among Örms allows them to e§ectively collude. Focusing on price leadership as the collusive mechanism, it is assumed that Örms commonly believe that price increases will be at least matched but lack any shared understanding about who will lead, when they will, and at what prices. Su¢ cient conditions are derived which ensure that supracompetitive prices emerge. However, price is bounded below the maximal equilibrium price.

**Jeudi 15 octobre 2015 12:45-13:45**- Campus Jourdan, bâtiment B, 1er étage, salle CMH
**TAKAHASHI Hidenori**(Mannheim) :__Strategic Design Under Uncertain Evaluations: Structural Analysis of Design-Build Auctions__- RésuméI investigate firms’ competition over price and product design under uncertain design evaluations in the context of Design-Build (DB) auctions. Reviewers’ design evaluations contain uncertainty from a bidder’s perspective, leading luck to dampen differences in firms’ chances of winning. I model bidders’ behavior and show semiparametric identification of the model primitives. Uncertain evaluations reduce the expected price of design quality, and exacerbate an auctioneer’s uncertainty in auction outcomes. A simple adjustment in the auction mechanism may completely shut down the impact of uncertain evaluations on bidding incentives, restoring efficient allocations of projects.

**Jeudi 8 octobre 2015 12:45-13:45**- Campus Jourdan, bâtiment B, 1er étage, salle CMH
**BOUACIDA Elias**(PSE) :__An application of behavioral welfare economics to consumption data__- Texte intégral [pdf]

**Jeudi 18 juin 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**WREN-LEWIS Liam**(PSE) :__*__

**Jeudi 11 juin 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**COMBE Julien**(PSE) :__The Design of Teacher Assignment : Theory and Evidence__**Co-author(s) : Olivier Tercieux et Camille Terrier**

**Jeudi 4 juin 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**DARGNIES Marie Pierre**(Université Paris-Dauphine) :__Gender Di fferences in Reactions to Feedback and Willingness to Compete__**Co-author(s) : Noémi Berlin**- RésuméIn Western societies, it is generally known men have a greater taste for competition than women. However, the determinants of the decision to enter competitions are still not fully understood. Providing feedback on relative performance reduces the gender gap in competitive entry. The aim of this paper is twofold. We rst evaluate how participants update their beliefs after receiving feedback informing them whether their performance is below or above the median performance. Second, we are interested in how men and women react to this information in terms of competitive entry. Our rst result is that participants, and women in particular, react more strongly to the feed- back they receive than would a Bayesian agent. As far as entry into the competition is concerned, below-median participants adjust their entry decision according to the competition they expect to face, while above-median participants do not. However, the behavior behind these results is quite di erent for men and women: women mainly re- act to information on their own performance, while men seem to respond more to their beliefs over the competition they will face. Moreover, most of the e ect of feedback and the information regarding the level of the competition on the decision to compete seems to operate via beliefs.

**Jeudi 28 mai 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**SEVERINOV Sergei**(University of British Columbia) :__Optimal Mechanisms for Budget Constraint Buyers__**Co-author(s) : A. Boulatov**- RésuméThe paper deals with the mechanism design for selling to buyers who have known budget constraints. With asymmetric budgets, our problem is that of asymmetric optimal mechanism design. We derive and characterize the optimal mechanism. It belongs to one of two classes. When the budget differences are small, the optimal mechanism discriminates only between high-valuation buyers for whom the budget constraint is binding. All low valuations buyers are treated symmetrically despite budget differences. In case of large budget differences, the optimal mechanism discriminates in favor of buyers with small budgets when the valuations are low, and it discriminates in favor of buyers with larger budgets when the valuations are high.

**Jeudi 7 mai 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**CAMARA Fanny**(Goethe University of Frankfurt) :__When Competition Hinders Transparency: Evidence from the Pharmaceutical Industry__

**Jeudi 9 avril 2015 12:45-13:45****RENOU Ludovic**(University of Essex) :__Revealed preferences over risk and uncertainty__**Co-authors : Matthew Polisson & John K.-H. Quah)**- RésuméConsider a finite data set where each observation consists of a bundle ofcontingent consumption chosen by an agent from a constraint set of such bundles. We develop a general procedure for testing the consistency of this data set with abroad class of models of choice under risk and under uncertainty. Unlike previous work, we do not require that the agent has a convex preference, so we allow for risk loving and elation seeking behavior. Our procedure can also be extended to calculate the magnitude of violations from a particular model of choice, using an index firstsuggested by Afriat (1972, 1973). We then apply this index to evaluate different models (including expected utility and disappointment aversion) in the data collected by Choi et al. (2007). We show that more than half of all subjects exhibiting choice behavior consistent with utility maximization are also consistent with models of expected utility and disappointment aversion.

**Jeudi 26 mars 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**BONTEMPS Christian**(Toulouse) :__*__

**Jeudi 19 mars 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MARLATS Chantal MARLATS**(Paris 2-Assas) :__Observation delays in teams__**Co-authors : Sid Gordon & Lucie Ménager**- RésuméWe study a dynamic team problem in which two players contribute to a common project that leads to a success with some probability increasing with effort. Players are informed of the success or the failure of their partner with a time lag. We interpret this delay as a technological constraint on information transmission. We find that the equilibrium payoff follows a regular cyclical pattern and the strategies are bang bang. This contrasts with the case without delay in which payoffs and efforts are constant over time. Also, there exists an asymmetric equilibrium if and only if the time lag is sufficiently small.

**Jeudi 5 mars 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**BERGES Alexis**(PSE) :__Investigating the impact of uncertainty on firms with dynamic costs on the electricity market__- RésuméWe provide an empirical analysis of the French electricity market. Specifically, we look at the impact of uncertainty on supplier strategies and take this as evidence that dynamic costs matter. Our approach to separate out the uncertainty from market demand expectations and predictability of renewables generation is novel. Both proxies for uncertainty used are new, uncertainty from market demand is inferred from the prediction errors that firms make in a demand estimation and uncertainty from renewable production is computed in a bottom-up approach from local weather forecasts. Instead of opting for a time series regression, we understand all hourly auctions as a cross-sectional dataset and control for the time of the day by using continuous transition variables for daytime periods. Similarly, we control for seasonality using continuous variables rather than dummies. Thereby, we are able to leverage our dataset and increase the sample size for each of our regression and improve the precision of our estimates.

**Jeudi 12 février 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**JEHIEL Philippe**(PSE) :__Investment strategy: Sampling, categorizing, and selection bias__- RésuméIn most cases, it is hard to have a good understanding of all possible (probablistic) consequences of investment decisions. I propose an approach in which decision makers first categorize projects based on similarity as perceived from small samples, then get access to aggregate statistics about the effect of the investment in the various categories of projects, and finally make investment decisions in randomly drawn projects based on these aggregate statistics. I compare the resulting outcome to that arising in a benchmark Bayesian model and highlight the mistakes of the selection bias type that such heuristics induce. I also apply the approach to multi-player contexts so as to shed light on the so called no trade theorem.

**Jeudi 5 février 2015 12:45-13:45****GORELKINA Olga**(Max Planck Institute, Bonn) :__Selling Money on Ebay__**Co-author(s) : Alia Gizatulina**- RésuméTo determine whether subjects display social preferences in the field, we conduct a trading experiment with a pool of German Ebay users. Acting as a seller, we offer Amazon gift cards with values from 5 to 500 euros. Randomly arriving buyers, the subjects of our experiment, make take-it-or-leave-it price offers. From each offer we infer the fraction of the gains from trade that a buyer proposes to leave to the seller. We find that a large numbers of offers correspond to approximately equal sharing between the buyer and the seller. The amount of money at stake has no significant effect on the relative prices offered. More experienced buyers are more likely to display behavior consistent with the theoretical model.

**Jeudi 15 janvier 2015 12:45-13:45****GORDON Sidartha**(Sciences Po) :__Information Choice and Diversity: The Role of Strategic Complementarities__- RésuméWe study a class of games where players face restrictions on how much information they can obtain on a common payoff-relevant state, but have some leeway in covertly choosing the dependence (or similarity) between their signals, before simultaneously choosing actions. Using a new dependence stochastic ordering between signals, we show that each player prefers and chooses information that is more dependent on the information of other players whose actions are either isotonic and complements with her actions or antitonic and substitutes with her actions. Similarly, each player prefers and chooses information that is less dependent on the information of other players whose actions are antitonic and complements with her actions or isotonic and substitutes with her actions. We then provide sufficient conditions for certain information structures to arise in equilibrium, in particular for public information and for private information. We discuss applications to collective action, oligopolies, supply chains, financial markets, and spec- ulative currency attacks. Equilibrium information structures may be inefficient. Making which signals were chosen (but not their realizations) publicly observable may restore efficiency.

**Jeudi 8 janvier 2015 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**GAGNEPAIN Philippe**(PSE - Paris 1) :__Knowledge Spillovers in Cost-Reduction Incentives__**Co-author(s) : Luis Aguiar**- RésuméThe goal of this paper is to identify and measure the relevance of knowledge spillovers in the French urban transport industry, where most regulated transportation networks are operated by firms that belong to the same company. We build and estimate a structural cost regulation model under incomplete information where the service is regulated by an authority and is provided by a single operator that may be owned by a larger company. We identify the knowledge spillovers which arise for some operators being linked to a same group, and see how they influence the firms’ decisions of exerting effort in order to reduce their operating costs. Our model provides us with estimates of the operators’ inefficiencies, the effort of the managers and the knowledge spillovers. Our results show that knowledge spillovers are indeed relevant for the existing industrial groups present in the French urban transport industry. Simulation exercises provide evidence of significant reductions in total operating cost following the enlargement of industrial groups and/or mergers between existing groups.

**Jeudi 27 novembre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**BLOCH Francis**(PSE -Paris 1) :__The formation of partnerships in social networks__**Co-autheur : Bhaskar Dutta**

**Jeudi 20 novembre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**HOUNGBONON Georges Vivien**(PSE) :__The impact of entry and merger on the pricing of multiproduct firm__- RésuméIn this paper, we design a hedonic pricing model to estimate the dynamic impact of entry and merger on access and usage prices in a context of mixed bundling between two independent services with respectively high and low valuations. Using telecommunications tariffs data from OECD operators and a double difference matching estimation strategy, we find that entry does not raises the access price of the services, irrespective of their valuation and whether in standalone or in bundle. However, merger does increase the bundle access price for the low valuation service while decreasing the standalone access price for the high valuation service. Although both the standalone and bundle usage prices of the low valuation service are also not affected by entry, they fall following a merger. For the high valuation service, entry decreases its standalone usage price while raising its bundle usage price. The inverse holds for merger.

**Jeudi 13 novembre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**SCHOLZ Eva-Maria**(Université Catholique de Louvain) :__How to license a downstream technology when upstream firms are capacity constrained?__- RésuméIn this paper we study the relationship between capacity constraints and licensing strategies. To do so, we focus on the licensing strategy of an outside patentee who licenses a process innovation to the downstream sector of a vertical Cournot oligopoly. Downstream firms source their input requirements from an upstream sector in which a subset of firms is capacity constrained. It is shown that (1) the patentee licenses large innovations via per-unit royalty contracts and small innovations via fixed-fee contracts; (2) an increase in the number of capacity constrained upstream firms makes it more likely that the patentee opts for a per-unit royalty contract; (3) depending on the number of capacity constrained upstream firms, privately optimal per-unit royalty contracts may maximise economic welfare.

**Jeudi 6 novembre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**HAGENBACH Jeanne**(Polytechnique) :__COMMUNICATION WITH EVIDENCE IN THE LAB__**Co-author : E. Perez-Richet**- RésuméWe examine strategic communication in sender-receiver games where senders can only transmit information using verifiable statements. Applying the method of Hagenbach, Koessler, Perez-Richet [Ecta14], we represent players’ incentives by a graph mapping which type of a sender would like to be believed as which other type, the masquerading graph. In theory, when this graph is acyclic, the receiver can deter the use of any vague message by attributing it to a type that no potential sender of this message would like to be. If receivers make such skeptical inferences, full revelation of information obtains in equilibrium. On the contrary, when the masquerading graph is cyclic, the use of vague messages is harder to discourage and full disclosure more difficult to sustain. This paper investigates the relevance of this graphical distinction in the lab. Our experimental design involves sender-receiver games with various payoffs and allows examining how subjects use and interpret evidences for the different resulting graphs. We show that information is more often revealed in games whose graph is acyclic than cyclic, and that receivers interpret vague evidences skeptically in most cases. While senders understand well when their type should be identified, they however fail using vague messages to fool receivers as finely as they could.

**Jeudi 16 octobre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MARFAN Manuel**(PSE) :__*__

**Jeudi 9 octobre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**ALAIN Marie-Laure**(Polytechnique) :__The Impact of Retail Mergers on Food Prices: Evidence from France__**Co-author(s) : Claire Chambolle, Stephane Turolla and Sofia B. Villas-Boas**- RésuméThis paper analyzes the impact of a merger in the French retail sector on food prices, using a consumer panel data. We perform a difference-in-differences analysis by comparing price changes in stores for which the local market structure is affected by the merger to unaffected stores. In addition, we empirically investigate economic forces behind the observed price changes. On average, we find that the merger significantly raised competitors’ prices contemporaneously with merging firms’ price increases. Further, we show that competitor prices increase more in local markets that experience larger structural changes in concentration and chain differentiation.
- Texte intégral [pdf]

**Jeudi 2 octobre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**STEPANOV Sergey**(Higher School of Economics, Moscow) :__Biased Performance Evaluation in A Model of Career Concerns: Incentives versus Ex-Post Efficiency__

**Jeudi 25 septembre 2014 12:45-13:45**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**GOMES Renato**(Toulouse School of Economics) :__Competitive Screening under Heterogeneous Information__**Co-author(s) : Daniel Garrett and Lucas Maestri**- RésuméWe study competition in price-quality menus when consumers privately know their valuation for quality (type), and are heterogeneously informed about the offers available in the market. While firms are ex-ante identical, the menus offered in equilibrium are ordered so that more generous menus leave more surplus uniformly over types. More generous menus provide quality more efficiently, serve a larger range of consumers, and generate a greater fraction of profits from sales of low-quality goods. By varying the mass of competing firms, or the level of informational frictions, we span the entire spectrum of competitive intensity, from perfect competition to monopoly.

**Jeudi 3 juillet 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MOULIN Hervé**(Rice University and Glasgow University) :__Segregation, Entropy, and Proportional Rationing__

**Jeudi 19 juin 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**ERDAMAR Bora**(PSE) :__On Manipulation from an Unacceptable Social Choice to an Acceptable One__**Co-author(s) : Remzi Sanver and Shin Sato**- RésuméNon-manipulability in collective decision making problems has been analyzed mainly through the axiom of strategy-proofness. In this paper, we propose a new concept of non-manipulability. We postulate that each agent misreports his preferences if and only if the misrepresentation leads to a change of the social outcome from an unacceptable one for this agent to an acceptable one. For the formulation of this idea the preference-approval framework is used. Possibility and impossibility results for the existence of a non-manipulable rule are provided.

**Jeudi 12 juin 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**LEVIN Dan**(Ohio State University) :__Separating Bayesian Updating from Non-Computational Reasoning: An Experimental Investigation__**Co-author(s) : James Peck et Asen Ivanov**- RésuméThrough a series of decision tasks involving colored cards, we provide separate measures of Bayesian updating and non-computational reasoning. We apply these measures to (and are the first to study) a common-value Dutch auction. This format is more salient than the strategically equivalent first-price auction and silent Dutch formats in hinting that one should condition one’s estimate of the value on having the highest bid. Both Bayesian updating skills and non-computational reasoning skills are shown to help subjects correct for the winners curse, as does the saliency of the active-clock Dutch format.

**Jeudi 5 juin 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**TREIBICH Rafael**(Polytechnique) :__Welfare Egalitarianism with Other-Regarding Preferences__- RésuméWe study the fair allocation of a one dimensional and perfectly divisible good when individuals have other-regarding preferences. A social ordering function associates any profile of ordinal preference relations with a complete ordering of all possible allocations. In both a model of average and positional externalities, we characterize a class of social ordering functions which satisfy appealing efficiency, fairness and consistency properties. These rankings require giving full priority to the worst off agent in the economy, where individual welfare is measured in a specific constructed way.

**Jeudi 22 mai 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**ISPANO Alessandro**(TSE & CREST) :__Competing over Gains, Cooperating over Losses__**Co-author(s): Peter Schwardmann (Toulouse School of Economics).**- RésuméWe let experimental subjects play a social dilemma game and vary whether payoffs are framed as losses or as gains. Subjects cooperate substantially more in the loss domain. We account for this finding with a theory that features noisy equilibrium behavior and reference-dependent risk preferences. We estimate a structural econometric model that incorporates risk preferences into an augmented cognitive hierarchy model. The estimated risk preference parameters are in line with evidence from individual decision-making tasks. Our model fits the experimental data well and is consistent with other puzzling results in the experimental literature on games played over losses. These findings have several important applications, including price competition between firms during recessions or concessions in climate change negotiations.

**Jeudi 15 mai 2014 12:45-15:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**LACLAU Marie**(PSE) :__Bayesian games with multiple priors__**Co-author : Ludovic Renou (Essex).**- RésuméWe study Sender-Receiver games where the Receiver has multiple priors over the states of the nature (the Sender may have a single or multiple priors). We assume full Bayesian updating and that the Receiver has max-min preferences. We establish necessary and sufficient conditions for a splitting lemma to hold. We derive a characterization of the equilibrium payoffs of the Sender.

**Jeudi 24 avril 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**REGUAND Mar**(Stanford GSB) :__Blowin' in the Wind: Sequential Markets, Market Power and Arbitrage__**Co-author(s): Koichiro Ito (Boston University)**- RésuméWe study strategic behavior of wind farms in electricity markets, and examine their dynamic adjustments through sequential markets. Wind production is uncertain and volatile, with the degree of uncertainty being reduced over the day. Therefore, sequential forward markets can improve market efficiency through information updating. However, pre-existing distortions such as market power and limited arbitrage may distort incentives to reveal accurate production forecasts. By using micro-level data in the Spanish electricity market, we show that wind farms exploit a forward market price premium, overstate their production over 20% at the day-ahead market, and only slowly adjust their commitments to expected production, increasing the dynamic inefficiencies from wind misplanning. Consistent with the premium being driven by market power, wind farms that have market power do not exploit the price premium, whereas competitive fringe farmers do the arbitrage. Our results show how pre-existing distortions can have unintended consequences in the market, making the integration of wind power even more challenging.

**Jeudi 10 avril 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**BOUSQUET Léa**(PSE) :__Time Inconsistency and Naivety within Hotelling Competition__- RésuméA monopoly offering a two-part tariff contract to time inconsistent consumers (both sophisticated and naive) do not exploit the time inconsistency bias but the naivety bias. Moreover, with perfect competition, firms do not succeed anymore to exploit the naivety bias even if an allocation inefficiency remains. So, we are interested to study the impact of Hotelling competition on the exploitation of these bias. We adapt DellaVigna and Malmendier (2004) framework to study the impact of imperfect competition and introduction of transport costs. These costs can be introduced at the contract period or at the consumption period. At the contract period, we observe that the competition even imperfect erases the exploitation of the naivety bias but the introduction of the transport costs conducts to a distortion between consistent and time inconsistent consumers. At the consumption period, transport costs generate an heterogeneity between consumers, firms are no longer able to provide a perfect commitment to sophisticated consumers. Consequently, allocation with both sophisticated and naive are not efficient.

**Jeudi 27 mars 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**WATSON Joel**(UC San Diego) :__Contractual Chains__- RésuméThis paper examines a model in which individuals contract with one another along the branches of a ?xed network and then select veri?able productive actions with externally enforced transfers. Special cases of the model include most settings of contracting with externalities that have been studied in the literature. The model allows for a type of externality that the previous literature has not explored fully—where a party is unable to contract directly with others whose actions affect his payoffs. The paper investigates the prospects for ef?cient outcomes under various contract-formation protocols (“contracting institutions”) and network structures. There are contracting institutions that always yield ef?cient equilibria for any connected network. A critical property is that the institutions allow for sequential contract formation or cancellation. The equilibrium construction features assurance contracts and cancellation penalties.

**Jeudi 20 mars 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**LEFEBVRE Perrin**(PSE) :__Lobbying, Informational Polarization and Political Contributions__**Co-author(s) : David Martimort**- RésuméCompeting interest groups can use two instruments to influence a decision maker: information supply, and monetary contributions. When engaging in informational lobbying, groups have to choose which elements of a political issue they want to focus on. Each element is ex ante more or less likely to serve each group's cause. We identify a tradeoff between the quality and the quantity of information the decision maker can get from group: the decision maker prefers ex ante neutral information, but it is more easy to induce groups to gather information about a priori favorable arguments. As a result of this tradeoff, the organization of lobbying will exhibit informational polarization, each group at equilibrium specializing in fields of expertise more likely to support their respective interest. Contributions do not qualitatively modify this result, but have an impact on groups' incentives to supply information. A group more efficient in the use of political contributions will tend to provide less information, while the effect of his competitors strength on a group's informational strategy is ambiguous. Depending on groups' efficiency in the use of contributions, information and contributions can appear as complement or substitute instruments.

**Jeudi 13 mars 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**DE BELSUNCE Henri**((International Max Planck Research School for Competition and Innovati) :__On Essential Patents and Vertical Structure in the Context of Cumulative Innovation__- RésuméThis paper focuses on the incentives to innovate in the context of cumulative innovation. It shows that the presence of essential patents exerts a detrimental effect on the innovation incentives of vertically integrated firms that hold a license reading on the essential technology and compares this effect under a property vs. liability regime. An application of the model shows that the effect also holds for licensees of patent pools hat feature a partial termination clause, e.g. MPEG-2. The partial termination clause extends the standard grantback requirement of patent pools to include related patents of pool licensees. The paper helps to explain the move of the DOJ in 2006 from a property rule to a liability rule for patent litigation cases involving essential patents, since the negative externality on cumulative innovation is exacerbated when courts employ a strict property rule for patent litigation cases. Furthermore, it suggests a possible explanation for the drop in innovation rates of pool outsiders who research in the technological proximity of the pool. Also, the paper gives a possible explanation for why vertically integrated firms are overrepresented (underrepresented) among the pool members (outsiders) as compared to pools that do not feature this clause. The model lends support to the finding that innovations made by outsiders are of higher quality then those of pool members. The pro-competitive effects, on which the Department of Justice based its positive ruling for the partial termination clause in the case of the MPEG-2 pool, are also a feature of the model.

**Jeudi 6 mars 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**SCHROEDER David**(Birkbeck College, University of London) :__A new measure of equity and cash flow duration: The duration-based explanation of the value premium revisited__- RésuméThis paper proposes a new method for estimating an expected equity and cash flow duration for individual shares. In analogy to bond duration, we derive duration from a share’s price sensitivity to changes in the discount rate. To ensure that the duration estimates are forward-looking, expectations of future cash flows are taken from equity analysts. In line with the duration-based explanation of the value premium, we find that value stocks have shorter durations than growth stocks. However, there is no significant relation between a firm’s cash flow duration and stock returns, which implies that cross-sectional differences in the firms’ cash flow timing cannot explain the value premium. Instead, we show that the firms’ equity duration can explain the cross-section of stock returns, and the value premium in particular.

**Jeudi 13 février 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**LEHLE Vincent**(Paris Dauphine) :__Afriat’s Theorem for Indivisible Goods__**Co-author : Françoise Forges**- RésuméWe identify a natural counterpart of the standard GARP for demand data in which goods are all indivisible. We show that the new axiom (DARP, for “discrete axiom of revealed preference”) is necessary and sufficient for the rationalization of the data by a well-behaved utility function. Our results complement the main finding of Polisson and Quah, Am. Econ. J.: Micro. 5(1) p.28-34 (2013), who rather minimally modify the original consumer problem with indivisible goods so that the standard GARP still applies.

**Jeudi 6 février 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**HOUNGBONON Georges Vivien**(PSE) :__Is there an optimal level of competition for maximal investment? Empirical evidence from the mobile telecommunications industry__**Co-author : François JEANJEAN (Orange, Regulatory Affairs)**- RésuméIn this paper, we use data from the mobile telecommunications industry to test whether there is an optimal level of competition which guarantees maximal investment in new technologies. Using the Lerner index of monopoly power as a measure of competition, we find an optimal level of competition at 62%. That is, investment rises from a low level of competition up to 62% and then falls above this level. The optimal level of competition is higher for firms which supply access to the fixed telecommunications network (65%), and lower for market leaders (56%). For laggards, the optimal level is much higher, at 80%. Our results suggest that antitrust agencies should consider the welfare implications of their competition policies when the Lerner index is close to 38%.

**Jeudi 23 janvier 2014 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**TSUR Matan**(University of Vienna) :__Financial Contracts and Bargaining__- RésuméI consider a firm with many projects; the output of each one will be sold to a prospective buyer. The terms of trade will be determined via some bargaining procedure. Projects require financing and the firm can borrow against the future revenue from the sales. I study how the firm’s financial obligations to an outside investor(s) influence the bargaining outcomes with prospective buyers. Does the firm prefer to bundle projects together and finance them jointly, e.g. taking out a single loan tied to the joint revenue, or finance them separately, e.g. with separate loans tied to different projects? The answer depends on the types of securities that are available. When constrained to standard debt, the firm extracts a larger share of the surplus by financing projects separately. But the advantage of separate financing is not preserved when the firm can design more complicated securities- convex combinations of debt and equity. The optimal securities are also characterized.

**Jeudi 12 décembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**BOYER Pierre**(Mannheim) :__Efficiency, Welfare, and Political Competition__**Co-author: Felix Bierbrauer**- RésuméWe study political competition under the assumption that voters have private information on their valuation of publicly provided goods. Preferencesare quasilinear in private goods consumption. We show that equilibrium policies are surplus-maximizing. This is in contrast to the conventional wisdom that incentive compatibility constraints make it harder to obtain surplus-maximizing outcomes. Our result extends to a Mirrlees (1971)-model of income taxation. In this model, however, the surplus-maximizing outcome can be interpreted as a political failure to provide for welfare-enhancing redistribution among individuals who differ in their productive abilities.

**Jeudi 5 décembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**TAKAHASHI Yuya**(Mannheim) :__Testing for Equilibrium Multiplicity in Dynamic Markov Games__**Co-authors : Taisuke Otsu and Martin Pesendorfer.**- RésuméThis paper proposes several statistical tests for finite state Markov games to examine the null hypothesis that the data are generated from a single equilibrium. We formulate tests of (i) the conditional choice probabilities, (ii) the steady-state distribution of states and (iii) the conditional distribution of states conditional on an initial state. In a Monte Carlo study we find that the chi-squared test of the steady-state distribution performs well and has high power even with a small number of markets and time periods. We apply the chi-squared test to the empirical application of Ryan (2012) that analyzes dynamics of the U.S. Portland Cement industry and test if his assumption of single equilibrium is supported by the data.

**Jeudi 28 novembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**HOLLARD Guillaume**(Paris 1) :__Non-strategic players are the rule rather than the exception__- RésuméIndependent studies on experimental games provide converging, and puzzling evidence: a noticeable fraction of players behave in a non-strategic way. It is hard to believe that so many players act in way that is hard to reconcile with any theory of strategic behavior. This study is designed to understand why. We test commonly suggested explanations such as insucient stakes, lack of attention or misconceptions about the game. None appear to be entirely convincing. Using reaction-time data, we show that non-strategic subjects spend time thinking about the games and do pay attention to changes. Moreover, players classied as non-strategic in a first set of games continue to act non-strategically in subsequent games. Our results suggest that the existence of non-strategic players in one-shot games is a robust feature of human cognition. Bearing in mind that our subjects are international chess players, we wonder why their strategic chess-playing ability does not transfer to laboratory games. Theoretical and economic consequences are discussed.
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**Jeudi 21 novembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**COLLIARD Jean-Edouard**(European Central Bank) :__Monitoring the supervisors: optimal regulatory architecture in a banking union__- RésuméI study the optimal architecture of bank supervision in a federal system. A central supervisor relies on off-site monitoring to learn about a bank's soundness, and then decides whether she should perform an on-site inspection or whether it is better left to local authorities. Local supervisors are more efficient at performing on-site examinations, but do not internalize cross-border externalities. The optimal degree of supervisory centralization depends on the severity of these externalities, the opacity of the supervised bank and the specificity of its assets. Cross-border externalities are endogenous as in equilibrium investors react to the supervisory architecture. Better supervision leads to more financial integration, which worsens the incentives of local supervisors. The economy can be trapped in an equilibrium with low supervision and low integration, while a forward-looking design of the supervisory architecture would coordinate economic agents on a superior equilibrium.
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**Jeudi 7 novembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**TERCIEUX Olivier**(PSE) :__Efficiency and Stability in Large Markets__**Co-autheur : Y-K. Che**

**Jeudi 31 octobre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**EHLERS Lars**(University of Montréal) :__Matching Markets under (In)complete Information__**Co-autheur(s): Jordi Masso**- RésuméWe introduce incomplete information to centralized many-to-one matching markets. This is important because in real life markets (i) any agent is uncertain about the other agents' true preferences and (ii) most entry-level matching is many-to-one (and not one-to-one). We show that given a common prior, a strategy prole is an ordinal Bayesian Nash equilibrium under incomplete information in a stable mechanism if and only if, for any true prole in the support of the common prior, the submitted prole is a Nash equilibrium under complete information in the direct preference revelation game induced by the stable mechanism.
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**Jeudi 24 octobre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**TARNAUD Razvan**(Paris 1) :__Information Aggregation using Logarithmic Market Scoring Rule__- RésuméThe success of early prediction markets have urged for the developments of market structures more adapted to beliefs elicitation. Thus, market scoring rules are more and more used in the pursuit of this goal. Although, they are often implemented in terms of asset trading, they are equivalent to a sequential probability report process that is studied in this paper. For the logarithmic market scoring rule, it is proven that the sequence of probabilities reported by agents converges under some assumptions on the regularity of the utility functions and the small variations of the risk aversion levels. In a multiple period setting, if agents update their probability beliefs with their limit reports, the sequence of probability beliefs of those who have not quoted yet converge towards a unique probability forecast, provided that their risk aversion levels are high enough. Interpreting this process as a strategic game with incomplete information, it is demonstrated that it converges towards a local equilibrium at each period and a global one which aggregates the private information hold by agents.

**Jeudi 10 octobre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MONTEIRO Juan Pablo**(Pontificia Universidad) :__When do non-linear contracts deter the expansion of (in)efficient rivals?__- RésuméWe study the anti-competitive effects of non-linear contracts (e.g., two-part tariffs, rebates, quantity discounts) between a buyer and a dominant firm in the presence of small rivals wishing to expand. While it is known that in a rent-shifting environment with imperfect information two-part tariffs are no different than the exclusionary contracts of Aghion and Bolton, we show that alternative non-linear schemes can be remarkably different. Quantity discounts that work entirely through the spot market (such as rebates) prevent the buyer and the incumbent to commit ex-ante to the transfer of rents. The effect is so strong that these contracts are rarely anticompetitive; more so the larger the dominant firm's bargaining power and/or outside option are. The reason we see these contracts is because they can be used to prevent the expansion of inefficient rivals, or more generally, to redistribute rents ex-ante between the buyer and the dominant firm.
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**Jeudi 3 octobre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**ROKETSKIY Nikita**(University College London) :__A Quantitative Analysis of the Used Car Market__- RésuméWe quantitatively investigate the allocative and welfare effects of secondary markets for cars. An important source of gains from trade in these markets is the heterogeneity in the willingness to pay for higher-quality (newer) goods, but transaction costs are an impediment to instantaneous trade. We explore how the income distribution affects this heterogeneity---income is an important determinant of willingness to pay for quality. Calibration of the model successfully matches several aggregate features of the U.S. and French used-car markets. Counterfactual analyses show that transaction costs have a large effect on volume of trade, allocations, and the primary market. Aggregate effects on consumer surplus and welfare are relatively small, but the effect on lower-income households can be large."

**Jeudi 26 septembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**MARTIN Daniel**(PSE) :__A Testable Theory of Imperfect Perception__- RésuméWe provide a new characterization of Bayesian expected utility maximization. The signature of the resulting theory is the impossibility of raising utility by switching wholesale from one action to another. We provide applications to robustness, to the recovery of utility from choice data, and to model classification.
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**Jeudi 12 septembre 2013 12:45-13:45**- Campus Jourdan, bâtiment G, rez-de-chaussée, salle 8
**KIMBALL Miles**(University of Michigan) :__Beyond Happiness and Satisfaction: Toward Well-Being Indices Based on Stated Preference__- RésuméThis paper proposes foundations and a methodology for survey-based tracking of well-being. First, we develop a theory in which utility depends on “fundamental aspects” of well-being, measurable with surveys. Second, drawing from psychologists, philosophers, and economists, we compile a comprehensive list of such aspects. Third, we demonstrate our proposed method for estimating the aspects’ relative marginal utilities — a necessary input for constructing an individual-level well-being index — by asking ~4,600 U.S. survey respondents to state their preference between pairs of aspect bundles. We estimate high relative marginal utilities not only for happiness and life satisfaction, but also for aspects related to family, health, security, values, and freedoms.
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**Jeudi 18 juillet 2013 12:45-13:45****RICHTER Michael**(Yeshiva University) :__Mechanism Design With Budget Constraints__- RésuméThis paper finds welfare- and revenue-maximizing mechanisms for assigning a divisible good to a population of budget-constrained agents where agents' have independently distributed private valuations and budgets. Both of these optimal mechanisms feature a linear price for the good. The welfare-maximizing mechanism additionally has a uniform lump sum transfer to all agents and a higher linear price than the revenue-maximizing mechanism. This transfer increases welfare because it relaxes the key di culty in the aforementioned setting: agents with high valuations cannot purchase an effi cient amount of the good because of their budget constraints. The welfare-maximizing result can therefore be interpreted as a version of the second welfare theorem. I show that both optimal mechanisms can be implemented using dominant strategies. In addition, I consider extensions where I relax the independence condition and introduce linear production.
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**Jeudi 13 juin 2013 12:45-13:45****FUDENBERG Drew**(Harvard) :__Recursive Stochastic Choice__**Co-author(s): Tomasz Strzalecki**- RésuméThis paper provides axiomatic characterizations of two sorts of recursive stochastic choice rules, where the agent makes his current decisions using a forward-looking value function that takes into account his future randomizations. Both of the choice rules we examine generalize logistic choice and are equivalent to it in static problems. The rules differ in how the agent views future choice sets and how he views his future randomizations. One rule is equivalent to the discounted logit used in applied work, and exhibits a preference for exibility;" the other is error-averse" and penalizes the addition of undesirable choices to a menu.
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**Jeudi 6 juin 2013 12:45-13:45****BERGES Alexis**(PSE) :__Dynamics on the electricity market : supply function equilibria and__**Co-author(s): D. Martimort**- RésuméWe investigate the influence of technology on the solutions to supply function equilibria models for the electricity market. We first stress the importance of considering adjustment costs, i.e. costs that depend not only on the quantity produced but also on the speed at which production varies: C(q, dq/dt). For linear demand and stochastic demand shocks, we then solve for a monopoly and a symmetric oligopoly. Our solutions are unique and depend on the distribution of shocks, accounting for interday and intraday supply function variation. Our results provide strong predictions on the dynamic evolution of bids on the day-ahead electricity market. We introduce a novel selection rule to choose from the continuum of equilibria typically obtained in usual supply function equilibria models, namely a solution’s stability to adjustment costs.

**Jeudi 23 mai 2013 12:45-13:45****POSTLEWAITE Andrew**(U. Penn) :__Optimism and Pessimism with Expected Utility__**Co-author(s): David Dillenberger et Kareen Rozen**- RésuméSavage (1954) provides axioms on preferences over acts that are equivalent to the existence of a subjective expected utility representation. We show that there is a continuum of other expected utility" representations in which for any act, the probability distribution over states depends on the corresponding outcomes and is

**Jeudi 16 mai 2013 12:45-13:45****GORDON Sidartha**(Science Po) :__Figures of Speech and Informative Strategic Communication__- Résumé> We provide a class of tractable communication games where each sender > type chooses a possibly truth-distorting figure of speech, which the > receiver interprets before choosing an action. Because language is > inherently vague, a figure of speech mapping determines > informativeness of communication: Exaggeration results in better > information transmission than understatement. A sender's choice of a > figure of speech trades off the action he wants to induce and his > lying aversion. There can be between one and five equilibria, all of > them fully separating, yet only partially revealing, which can be > ranked by level of informativeness. At most two of these equilibria, > the less informative ones, are ironic. The other (at most three) > equilibria are straight-talking, either exaggerating or understated. > We find that a receiver may prefer a sender who is more dissimilar to > him, and also a sender who is less honest. He may prefer a language > that has more vagueness, and a sender who is less competent. Finally, > we study the limit of the equilibria as either (i) the language > vagueness vanishes or (ii) the lying aversion vanishes.

**Jeudi 25 avril 2013 12:45-13:45****DE CORNIERE Alexandre**(Oxford) :__Integration and Search Engine Bias__**Co-author(s): Greg Taylor (Oxford)**- RésuméCompetition authorities all over the world worry that integration between search engines (mainly Google) and publishers could lead to abuses of dominant position. In particular, one concern is that of own-content bias, meaning that Google would bias its rankings in favor of the publishers it owns or has an interest in, to the detriment of competitors and users. In order to investigate this issue, we develop a theoretical framework in which the search engine (i) allocates users across publishers, and (ii) competes with publishers to attract advertisers. We show that the search engine is biased against publishers that display many ads---even without integration. Although integration may lead to own-content bias, it can also reduce bias by increasing the value of a marginal consumer to the search engine. Integration also has a positive effect on users by reducing the nuisance costs due to excessive advertising. Its net effect is therefore ambiguous in general, and we provide sufficient conditions for it to be desirable or not.
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**Jeudi 18 avril 2013 12:45-13:45****LEFEBVRE Perrin**(PSE) :__Horizontal differentiation in lobbying__- RésuméThis paper considers strategic information gathering by competing interest groups that want to influence an uninformed decision-maker. Policy decision depends on different parameters, and groups can choose which parameters to specialize into when searching for information. Common wisdom wants groups to differentiate by specializing in different dimensions in order to soften competition. I show that differentiation is indeed the only equilibrium when dimensions are equally relevant; but far from softening competition, it increases the groups search cost without guaranteeing better policies. Compared to a situation where groups concentrate on the same information, differentiation favors the decision-maker and hurts interest groups. I also characterize the different types of equilibria when the decision-maker attributes different weights to different dimensions.

**Jeudi 11 avril 2013 12:45-13:45****LISKI Matti**(Aalto University School of Economics, Helsinki) :__Resource relationships__**Co-author(s): Reyer Gerlagh**- RésuméWe consider a model of resource dependence where only the seller knows the resource reserve. The model captures phenomena such as trust in the relationship and "bribing" for continuation through generous supplies. It also explains supply shocks in equilibrium: privately informed sellers have incentives to reveal their types too late through a supply disruption after which their exploit the consumers inability to immediately adjust demand. Two puzzles that a standard exhaustible-resource theory cannot explain are resolved: sellers have an incentive to overstate their resources rather than emphasize scarcity, and buyer's can switch to alternatives before exhausting the resource thereby leaving socially valuable resource in the ground.

**Jeudi 4 avril 2013 12:45-13:45****GENDRON-SAULNIER Catherine**(Université de Montreal) :__Information Sourcing in a Strategic Environment__- RésuméMany models in economics assume that individuals are endowed with exogenous information. Yet, individuals are making choices about what to learn and from which sources of information. In this paper, we study the sourcing decisions of individuals interacting in a game where the payoff function is quadratic and the information structure is gaussian. Our game is as follows. There are two players that have to make two sequential decisions. First, each player chooses his sources of information independently of, and simultaneously with, the other player. Then each player chooses an action after observing the realization of the signals send by the sources he chose in the first step, but not the signals of the other player (unless they have chosen the same information sources). As a motivating example we consider the situation of two oligopolists competing in price on a market for a differentiated good that acquire information on their demand function. We answer the question of whether the players make the same sourcing decisions and how similar the information they acquire is. We also perform some static comparative exercises and provide some welfare analysis.

**Jeudi 21 mars 2013 12:45-13:45****DE NIJS Romain**(Hass School of Business) :__An empirical assessment of the effects of the French Hadopi law__**Co-author(s) : C. Bellégo**- RésuméThis article uses the French anti-piracy law known as Hadopi, to study the effects of online piracy on movie box office performances. Results from difference-in-differences estimations indicate that the law increased admissions in movie theaters by 13 percent in France relative to control countries. Results also show that the Hadopi effects tend to decrease over time and are particularly strong for American movies that are the most heavily pirated movies. Last, the Hadopi effects are very unlikely to be explained by supply side reactions of the industry nor by a concomitant but unrelated to Hadopi positive shock in the French market for movies in theaters.
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**Jeudi 7 mars 2013 12:45-13:45****ZHOU Junjie**(PSE) :__Economics of Leadership and Hierarchy__- RésuméThis paper explores leadership within hierarchical organizations. For each hierarchy, I consider a dynamic signaling game in which each player observes only the actions of his direct superiors before choosing his action. At the top of the hierarchy are the leaders, who learn the state from nature. The hierarchy controls the flow of information and the timing of the game, and determines the equilibrium output and welfare. I show that the welfare-optimal hierarchy is the chain, because it maximizes the incentive of players to ``lead by example'' for their subordinates. The chain remains optimal even in the presence of verifiable or unverifiable costly information acquisition by the leaders. Lastly, I characterize optimal hierarchies when the number of layers or the number of leaders is limited. Applications to fund-raising are also discussed.
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**Jeudi 28 février 2013 12:45-13:45****LECOUTEUX Guilhem**(Ecole Polytechnique) :__The formation of preferences in game theory__- RésuméFollowing Hausman's analysis of the concept of preferences (Preference, Value, Choice and Welfare, Cambridge University Press, 2012), we suggest modelling the formation of preferences in game theory, by introducing a distinction between utility --- defined as individual welfare --- and preferences --- defined as a subjective total comparative evaluation. We provide then an analytical framework where players can choose their own preferences before playing a game, and introduce the $\Sigma$ -equilibrium as a new notion of equilibrium in non cooperative game theory in order to model such a decision process. This notion of equilibrium seems to present more robust methodological foundations and also to have a better predictive power than Nash equilibrium in some standard games, and that is why we suggest it as a substitute to Nash equilibrium. We show that in a very large class of games, if we assumed that players choose their preferences in order to maximize in fine their utility, they will generally decide to maximize a different function than their own utility function: this means that for a very large class of games, maximizing one's own utility is self-defeating. We show that players choose their preferences in order to get a strategic advantage on the other players, such that the strategy that satisfies their preferences is in fact the strategy they would play if they were a Stackelberg leader. A direct corollary of this result in welfare economics is that --- if we assume that players are rational --- the preferences of the individuals are in general distinct from their utility: therefore preference satisfaction is not welfare, and we cannot easily infer individual welfare from choices and preferences.

**Jeudi 21 février 2013 12:45-13:45****SCHUTZ Nicolas**(University of Mannheim) :__Cross-Border Price Effects of Mergers and Acquisitions - A Quantitative Framework for Competition Policy__**Co-auteurs : Holger Breinlich and Volker Nocke**- RésuméDecisions of national competition authorities have important effects on other jurisdictions. We provide a framework to quantify the domestic and cross-border effects of mergers, and to draw conclusions for the coordination of national merger policies. We develop a two-country model with many sectors. In each sector, producers vary in terms of their marginal costs, and are engaged in Cournot competition. We allow for pro?table mergers to take place subject to the non-violation of a given national competition policy. Because of trade costs and perceived differences in qualities between domestic and foreign products, mergers may have different consumer surplus effects in the home and the foreign country. We calibrate the model using data for the year 2002 for 167 manufacturing sectors in the U.S. and Canada, two well-integrated markets where cross-border effects of M&As are likely to be important. We choose parameters to match relevant moments in the data, including industry sales, concentration ratios and trade ?ows. We ?nd that merger decisions taken in isolation by national competition authorities lead to ine cient outcomes compared to a scenario where competition policy is coordinated, and that these ine ciencies are quantitatively important. While there is considerable variation across industries, we ?nd that in the majority of industries a merger approval policy based on domestic consumer surplus is too restrictive from the viewpoint of the neighboring country.
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**Jeudi 14 février 2013 12:45-13:45****LASLIER Jean-François**(Ecole Polytechnique) :__Vote au pluriel: How people vote under different voting rules__- RésuméThe seminar presents a survey of recent research on voter behavior. Using traditional laboratory experiments, innovative "in situ" experiments, and on-line surveys, we observe how people vote under different voting rules. The goal of the investigation is two-fold. In an Institutional Design perspective, we want to understand the consequences of possible political institutions (who is elected ?). In a Political Psychology perspective, we want to understand the individuals' conception of the act of voting. The set of candidates being given, we describe what kind of candidates are favored by what kind of rules. As to voters, we find that they use heuristics and behave partly strategically and partly sincerely, the mixture depending on the detailled circumstances. We note that voters have both self-serving and ideological preferences over voting rules.

**Jeudi 7 février 2013 12:45-13:45****GARRETT Daniel**(TSE) :__Dynamic Mechanism Design with Dynamic Arrivals and Changing Values__- RésuméI will discuss dynamic mechanism design settings where agents preferences evolve stocastically and where agents arrive over time. Agents need not participate at the arrival date and can be strategic with respect to the first date of participation in the mechanism. Profit-maximizing allocations, which maximize a “dynamic virtual surplus” are derived. Applications to the durable goods problem (see `Incoming Demand with Private Uncertainty’) and overselling of capacity in the airline industry (see `Overbooking’ with Jeff Ely and Toomas Hinnosaar) will be discussed.

**Jeudi 24 janvier 2013 12:45-13:45****DAVE Chetan**(NYU Abu Dhabi) :__Confirmation Bias with Motivated Preferences__**co-authored with Gary Charness**- RésuméModels of confirmation bias as an individual decision making error predict systematic departures from Bayesian updating and can imply that no learning may ever take place. While some experimental evidence for a confirmation bias has been found, an implicit assumption in many stochastic economic models is that strategic (or market) pressures cause individuals to not exhibit systematic deviations from Bayesian updating. We investigate in the laboratory the effect of subtle background strategic considerations on signal extraction, finding that people are affected by the presence of motivated preferences (here a preference for one state having manifested). Our results suggest that players with motivated preferences over probabilistic end states deviate less from Bayesian updating. However, such players still exhibit a confirmation bias when the directions of updates are analyzed.

**Jeudi 10 janvier 2013 12:45-13:45****JEONG HEO Eun**(University of Rochester) :__Probabilistic Assignment Problem with Multi-unit Demands: A Generalization of the Serial Rule and a Characterization__- RésuméAbstract: We study a probabilistic assignment problem when agents have multi-unit demands for objects. We first introduce two fairness requirements to accommodate di erent demands across agents and show that each of these requirements is incompatible with stochastic dominance efficiency (henceforth, we use the prefix sd" for stochastic dominance) and weak sd-strategyproofness, unless all agents have unitary demands. We next introduce a new incentive requirement which we call limited invariance. We explore implications of these requirements, together with consistency and converse consistency. Our main result is that the generalized serial rule, which we propose as an adaptation of the serial rule to our setting, is the only rule satisfying sd-efficiency, the sd proportional-division lower-bound, limited invariance, and consistency. Uniqueness persists if we replace the sd proportional-division lower-bound by sd normalized-no-envy, or consistency by converse consistency, or both. The serial rule in Bogomolnaia and Moulin (2001) is characterized as a special case of our generalized serial rule.

**Jeudi 13 décembre 2012 12:45-13:45****WREN-LEWIS Liam**(PSE) :__Hold-up problems in international electricity trade__- RésuméThis paper investigates the underdevelopment of electricity trade between African coun- tries. I build a model where hold-up problems originating from incomplete contracts decrease countries' willingness to trade. In particular, an inability to commit to future trade reduces the specialisation of investment. The paper then uses the model to explore potential policy solutions including deregulation and the liberalisation of ownership.

**Jeudi 6 décembre 2012 12:45-13:45****CANTALLA David**(Centro de Estudios Economicos, El Colegio de Mexico) :__Housing Markets with Endogenous Budget Constraints__**Co-auteur : Juan Sebastian Pereyra**- RésuméThis paper addresses the existence of competitive equilibrium in the variant of the Assignment Game where budget-constrained agents are endowed with one good, that can be sold to buy another good. We de?ne the Money Scarcity (MS) condition and its Strong (SMS) and Weak (WMS) versions. The WMS condition ensures the existence of an equilibrium in cases where Quinzii’s indis- pensability of money assumption does not hold. We consider two mechanisms to ?nd a competitive equilibrium which are extended versions of Gale’s Top Trad- ing Cycles algorithm and of the Exact Auction Mechanism of Demange, Gale and Sotomayor. Under MS, the ?rst mechanism is strategy-proof; the second is not. We strengthen the MS condition (SMS) to guarantee the existence of Nash equilibria in the revelation game induced by the second mechanism, where the outcome coincides with the assignment found by the ?rst mechanism; moreover, this assignment is Pareto e?cient.

**Jeudi 29 novembre 2012 12:45-13:45****POZZI Andrea**(Einaudi Institute for Economics and Finance) :__The Effect of Internet Distribution on Brick-and-mortar Sales__- RésuméI study the introduction of an online shopping service for a large supermarket chain that also operates a wide network of brick-and-mortar stores. The establishment of the Internet channel led to a 13 percent increase in overall revenues, inducing only limited cannibalization on traditional sales. I provide insights on the mechanism behind this result. I show that selling on the web removes travel costs and helps the retailer to attract new business from customers living far away from its stores. I also document that revenues increase more in markets where the chain faces more competitors. This suggests that the new sales represent in part business diverted from rival supermarkets.

**Jeudi 15 novembre 2012 12:15-13:45****MARFAN Manuel**(PSE) :__Rules versus discretion under limited commitment__- RésuméThis paper studies decision making by an uninformed authority that will be better informed in the future, and whose expected actions will affect a third party’s decision making. The trade-off between rules and discretion is studied in this setting, when information is not verifiable by the third party, thus inducing the authority to misreport it. A necessary and a sufficient condition for continuity of the decision rule as a function of the information parameter are given, and under some structural conditions the optimal mechanism is characterized.

**Jeudi 25 octobre 2012 12:45-13:45****SPECTOR David**(PSE) :__"Non-verifiable self-reporting and collusion"__- RésuméMany cartels involve companies reporting their sales to their competitors in a non-verifiable way, long before individual sales information becomes public. This paper assesses how the possible collusive outcomes depend on the possibility of engaging in such cheap talk. It is shown that for some parameter values, monopoly prices can be sustained in equilibrium only if such cheap talk is possible. The reason is that if communication is precluded, the occurrence of wasteful price wars may be the only way to deter deviations, whereas the possibility of communicating frequently, even if only by issuing non-verifiable reports, allows companies to fine-tune more efficient disciplining devices such as voluntary, temporary self-exclusion.

**Jeudi 11 octobre 2012 12:45-13:45****HEINRICH Nax**(PSE) :__"The Evolution of Core Stability in Decentralized Matching Markets"__**Co-auteur : Peyton Young, Bary Pradelski**- RésuméDecentralized matching platforms on the internet allow large numbers of agents to interact anonymously at virtually no cost. Very little information is available to market participants and trade takes place at many different prices simultaneously. We propose a decentralized learning process in such environments that leads to stable and efficient outcomes. Agents on each side of the market make demands of potential partners and are matched if their demands are mutually compatible. Matched agents occasionally experiment with higher demands, while unmatched agents lower their demands in the hope of attracting partners. This learning process implements core allocations even though agents have no knowledge of other agents’ strategies, payoffs, or the structure of the game, and there is no central authority with such knowledge either.
- Texte intégral [pdf]

**Jeudi 27 septembre 2012 12:45-13:45****WILNER Lionel**(Crest -LEI) :__"Do consumers correctly expect price reductions? Testing dynamic behavior"__**Co-auteur : Philippe Février**- RésuméBoth theoretical and empirical dynamics literature require agents to solve complex dynamic programs given their information set, which assumes implicitly that agents are fully rational and have perfect expectations. We claim that this assumption is easily testable provided that market-level data on prices and purchases are available. Using data on albums exhibiting frequent episodes of sales, we perform the test and find that consumers hold simple expectations on the timing of sales: everything happens as if consumers were expecting a Markov price process. On the contrary, the firm is more sophisticated and does not follow such a policy. Our results are coherent with the idea that agents rationality is bounded because of limited memory or limited capacity. These results have important implications in terms of demand estimation, firms' optimal pricing strategy and welfare.

**Jeudi 20 septembre 2012 12:45-13:45****WEINSTEIN Jonathan**(Northwestern University) :__"A Bayesian Foundation for Classical Hypothesis Testing."__- RésuméA decision-maker can ensure dynamic consistency by following Bayes' rule, but he may wish to balance such consistency against other goals. That is, when the decision-maker is surprised by a pattern unaccounted for in his prior, he may wish to change his beliefs in a way which violates Bayes' rule, but he may also wish to limit his inconsistency. We show that if such non-Bayesian events, or \paradigm shifts," are rare, in the sense that they occur only with a small probability according to the decision-maker's initial belief, the decision-maker will be \approximately" dynamically con- sistent. Our notion of \approximate" dynamic consistency is that the possible arbitrage against the decision-maker is small compared to the size of his transactions. The quantity is equivalent to the level of a classical hypothesis test, so our results provide a decision-theoretic foundation for the classical criteria for rejecting a null hypothesis. Our ndings give the decision-maker some latitude to revise his model while bounding the pain of inconsistency, and unify the classical and Bayesian modes of inference.
- Texte intégral [pdf]

**Jeudi 5 juillet 2012 12:45-13:45****SALOMON Antoine**(Imagine, Ecole des Ponts ParisTech) :__Strategic learning and bandit games__

**Jeudi 14 juin 2012 12:45-13:45****TESCHL Miriam**(University of Vienna) :__Theory of choice under internal conflict__

**Jeudi 31 mai 2012 12:45-13:45****LEFEBVRE Perrin**(PSE) :__Downstream lobbying and informational frictions__

**Jeudi 24 mai 2012 12:45-13:45****MICHELUCCI Fabio**(CERGE-EI, Pragues) :__The English Auction, Rushes, and a Selaed Bid Efficient Auction__- Texte intégral [pdf]

**Jeudi 10 mai 2012 12:45-13:45****KRANTON Rachel**(Duke University and PSE) :__Striving for Social Status in Networks__

**Jeudi 5 avril 2012 12:45-13:45****KUSHNIR Alexey**(University of Zurich) :__A geometric approach to mechanism design__

**Jeudi 29 mars 2012 12:45-13:45****VANASCO Victoria**(UC Berkeley and PSE) :__Learning by Lending: The Informational Role of Financial Intermediaries__

**Jeudi 22 mars 2012 12:45-13:45****LACLAU Marie**(HEC Paris) :__Communication in repeated network games with private monitoring__

**Jeudi 15 mars 2012 12:45-13:45****KANDORI Michihiro**(University of Tokyo) :__Asynchronous Revision Games__- Texte intégral [pdf]

**Jeudi 8 mars 2012 12:45-13:45****OZGUR Onur**(Université de Montréal) :__Dynamic Linear Economies with Social Interactions__

**Jeudi 16 février 2012 12:45-13:45****TRUYTS Tom**(U. Leuven) :__Stochastic Signaling: Information Substitutes and Complements__

**Jeudi 9 février 2012 12:45-13:45****SPAETER Sandrine**(BETA, Univ. Strasbourg) :__The Prudent Principal__**Co-author(s): Bernard Sinclair-Desgagné**- Texte intégral [pdf]

**Jeudi 2 février 2012 12:45-13:45****KOLM Julian**(Université de Vienna) :__Learning Across Subgames: An Application to the Hold-up Problem"__- Texte intégral [pdf]

**Jeudi 12 janvier 2012 12:45-13:45****GUESNERIE Roger**(PSE) :__Eductive Stability in Real Business Cycle Models__**Co-author(s): G. Evans & B. McGough**- Texte intégral [pdf]

**Jeudi 5 janvier 2012 12:45-13:45****CASELLA Alessandra**(University Columbia) :__Vote trading with and without party leaders__**Co-author(s) Tom Palfrey & Sebastien Turban**- Texte intégral [pdf]

**Jeudi 15 décembre 2011 12:45-13:45****CHASSAGNON Arnold**(U. Tours & PSE) :__Multiple lenders, strategic default and the role of debt covenants__

**Jeudi 1er décembre 2011 12:45-13:45****GUERON Yves**(UCL ) :__Failure of Gradualism under Imperfect Monitoring__

**Jeudi 17 novembre 2011 13:00-13:45****MARCH Christoph**(PSE ) :__Do We Follow Others when We Should? A Simple Test of Rational Expectations__**Attention exceptionnellement ce séminaire commencera à 13h**- RésuméWeizsäcker (2010) suggests a simple counting technique to test the rational-expectations hypothesis in experimental datasets. The counting technique is applied to data on information cascade games and regression results strongly reject the rational-expectations hypothesis. Weizsäcker (2010) concludes that participants perform poorly when trying to extract the information that is contained in others' choices. We replace participants' choices with equilibrium choices in the cascade game dataset and we show that the counting technique sometimes leads to the erroneous conclusion that players follow their signal more often than they follow others even when the latter is the optimal decision. We correct the counting technique and we conclude that, in situations where it is empirically optimal to follow others, participants do so in the large majority of cases. We conrm that the rational-expectations hypothesis is rejected in cascade game experiments.

**Jeudi 10 novembre 2011 12:45-13:45****RUIZ-ALISEDA Francisco**(Ecole Polytechnique ) :__The Dynamics of Protection and Imitation of Innovations__**with Emeric Henry**- RésuméMost innovators choose not to patent their inventions. This is somewhat of a puzzle for those who view innovators as at the mercy of imitators in the absence of legal protection. In practice, innovators invest actively in making their products technologically hard to reverse-engineer. In this paper, we consider the dynamics of imitation and protection of innovations, and we find that innovators can still obtain high profits in the absence of legal protection. The protection technologies that yield the highest profits for the innovator are expensive and do not protect well. Our model also allows us to draw conclusions on the design of patent policy and on the dynamics of employment and mobility of researchers in innovative industries.

**Jeudi 20 octobre 2011 12:45-13:45****KOESSLER Frederic**(PSE) :__Extortion and Political Risk Insurance in Weak Governance Countries__

**Jeudi 13 octobre 2011 12:45-13:45****BIANCHI Milo**(U. Paris-Dauphine) :__Creative Accounting and Efficient Markets__

**Jeudi 6 octobre 2011 12:45-13:45****DE CORNIERE Alexandre**(PSE) :__Search Advertising__

**Jeudi 29 septembre 2011 12:45-13:45****COLLIARD Jean-Edouard**(PSE) :__Rational Blinders: Is it Possible to Regulate Banks Using their Internal Risk Models?__

**Jeudi 23 juin 2011 12:45-13:45****MARCH Christoph**(PSE) :__Individual Learning and Strategic Thinking in Laboratory Cascades__

**Jeudi 9 juin 2011 12:45-13:45****KORIYAMA Yukio**(Ecole Polytechnique) :__Optimal Apportionment__**Co-auteur(s) : Jean-François Laslier**- Texte intégral [pdf]

**Jeudi 19 mai 2011 12:45-13:45****BEHRINGER Stefan**(University of Bonn) :__Price Wars in Two-Sided Markets: The case of the UK Quality Newspapers__**Co-auteur(s) : Lapo Filistrucchi**- Texte intégral [pdf]

**Jeudi 5 mai 2011 12:45-13:45****LAMY Laurent**(PSE) :__On the use of absolute auctions and secret reserve prices__**Co-auteur(s) : Philippe Jehiel**

**Jeudi 28 avril 2011 12:45-13:45****SAND-ZANTMAN Wilfried**(Toulouse School of Economics) :__Contracting with Bypass in Bilateral Relationship__**with Bruno Jullien and Jerome Pouyet**

**Jeudi 7 avril 2011 12:45-13:45****LIMARDI Michela**(PSE) :__Nongovernmental Regulation: NGO Monitoring and Firm Compliance with Social Standards__

**Jeudi 31 mars 2011 12:45-13:45****BRAOUEZEC Yann**(Ecole Supérieure d’Ingénieurs Léonard de Vinci) :__Some theory of constrained third-degree price discrimination__

**Jeudi 24 mars 2011 12:45-13:45****BRAMOULLE Yann**(Université Laval) :__Favoritism__- Texte intégral [pdf]

**Jeudi 10 mars 2011 12:45-13:45****LEVY Raphaël**(University of Mannheim) :__Humouring both parties: a model of two-sided reputation__

**Jeudi 3 mars 2011 12:45-13:45****TUKIAINEN Janne**(University of Helsinki) :__The Effect of Minimum Bid Increment on Revenue in Internet Auctions: Evidence from a Field Experiment__- Texte intégral [pdf]

**Jeudi 10 février 2011 12:45-13:45****LEVY Raphaël**(U. Mannheim - TBA) :__*__

**Jeudi 3 février 2011 12:45-13:45****GOSSNER Olivier**(PSE) :__Entropy and the value of information for investors__**Co-auteur(s) : Antonio Cabrales & Roberto Serrano**- Texte intégral [pdf]

**Jeudi 20 janvier 2011 12:45-13:45****MORENO DE BARREDA Ines**(LSE) :__Cheap Talk With Two-Sided Private Information__- RésuméI investigate the strategic interaction between a perfectly informed expert and a decision maker when the latter has imperfect private information relevant to the decision. To analyse the effect of the decision maker's information, I extend the Crawford and Sobel (1982) canonical model of cheap talk by allowing the decision maker to access an unbiased and symmetric signal about the state of the world. I first show that for symmetric preferences partition equilibria exist in this more general environment. Second, for quadratic-loss preferences, I show that access to private information might hamper communication. Surprisingly, in a wide range of environments, the decision maker private information cannot make up for the loss in communication implying that the welfare of both agents decreases.
- Texte intégral [pdf]

**Jeudi 6 janvier 2011 12:45-13:45****BIANCINI Sara**(Thema, Cergy) :__Intellectual Property Rights Adoption in Developing Countries__

**Jeudi 9 décembre 2010 12:45-13:45****KOVBASYUK Sergei**(TSE and CREST) :__Optimal Certification Design__

**Jeudi 2 décembre 2010 12:45-13:45****GODEFROY Raphael**(PSE) :__Choosing Choices: Agenda Selection with Uncertain Issues__- Texte intégral [pdf]

**Jeudi 25 novembre 2010 12:45-13:45****DE CORNIERE Alexandre**(PSE & CREST-ENSAE) :__Online Advertising and Privacy__**with Romain de Nijs**

**Jeudi 28 octobre 2010 12:45-13:45****VIDA Peter**(University of Vienna) :__Collusion communication schemes in first price auction__

**Jeudi 14 octobre 2010 12:45-13:45****COLLIARD Jean-Edouard**(PSE) :__The Impact of Private Information about Positive Feedback Trading__

**Jeudi 7 octobre 2010 12:45-13:45****PAWLOWITSCH Christina**(PSE) :__Why evolution does not necessarily lead to an optimal signaling system__- Texte intégral [pdf]

**Jeudi 30 septembre 2010 12:45-13:45****MARCH Christopher**(PSE) :__Adaptive Social Learning__- Texte intégral [pdf]

**Mardi 8 juin 2010 12:45-13:45****BRESKY Michal**(CERGE-EI, Prague) :__Revenue and Efficiency in Multi-Unit Uniform-Price Auctions__

**Jeudi 3 juin 2010 12:45-13:45****PICARD Pierre**(Ecole Polytechnique: TBA) :__*__

**Jeudi 27 mai 2010 12:45-13:45****DE NIJS Romain**(PSE) :__Dynamic Targeted Pricing in Online Markets__

**Jeudi 20 mai 2010 12:45-13:45****CRAWFORD Vincent**(Oxford) :__New York City Cabdrivers’ Labor Supply Revisited: Reference-Dependent Preferences with Rational-Expectations Targets for Hours and Income__**with Juanjuan Meng**- Texte intégral [pdf]

**Jeudi 13 mai 2010 12:45-13:45****BRESKY Michal**(CERGE-EI, Prague) :__Revenue and Efficiency in Multi-Unit Uniform-Price Auctions__

**Jeudi 6 mai 2010 12:45-13:45****LASLIER Jean-François**(Ecole Polytechnique) :__Stubborn learning__**with Bernard Walliser**- Texte intégral [pdf]

**Jeudi 8 avril 2010 12:45-13:45****La séance a été annulée.****LAMY Laurent**(PSE : TBA) :__*__

**Jeudi 25 mars 2010 12:45-13:45****JANSEN Jos**(Max Planck Institute ) :__Share To Scare: Technology Sharing in the Absence of Intellectual Property Rights__- Texte intégral [pdf]

**Jeudi 11 mars 2010 12:45-13:45****GOSSNER Olivier**(PSE : TBA) :__A Folk Theorem in Robust Equilibrium Structures.__

**Jeudi 11 mars 2010 12:45-13:45**- *

**Jeudi 18 février 2010 12:45-13:45****FERAL Arnaud**(U. Cergy : TBA) :__Merger Control with Transfers from the Capital Gains Tax__

**Jeudi 4 février 2010 12:45-13:45****PERONA Mathieu**(PSE) :__How broadcasting quotas harm program diversity__

**Jeudi 28 janvier 2010 12:45-13:45****MARTIMORT David**(TSE) :__Public Contracting in Delegated Agency Games__**with Lars Stole - David Martimort will be at PSE-Jourdan on thursday (building E), please fill this form if you want to meet him**

**Jeudi 21 janvier 2010 12:45-13:45****TOXYAERD Flavio**(University of Cambridge) :__The Economics of Infectious Disease__

**Jeudi 10 décembre 2009 12:45-13:45****HARSTAD Ron**(University of Missouri) :__Two Examples of Why I've Worked with Mike Rothkopf : "Winner's Curse Corrections Magnify Adverse Selection" (joint with Robert Bordley) and "Auctioning Rights to Choose When Competition Persists"__- Texte intégral [pdf]

**Jeudi 26 novembre 2009 12:45-13:45****ROGERS Brian**(Northwestern) :__Diversity and Popularity in Social Networks (avec Yann Bramoulle).__**Brian Rogers sera à Jourdan la journée, contactez moi si vous voulez le rencontrer, ou complétez ceci: http://www.doodle.com/6paq5gc44vys3hzi**- Texte intégral [pdf]

**Jeudi 12 novembre 2009 12:45-13:45****TERCIEUX Olivier**(PSE) :__Common p-Beliefs and the Hold-Up Problem (avec Philippe Aghion, Drew Fudenberg, Richard Holden et Takashi Kunimoto)__- Texte intégral [pdf]

**Jeudi 15 octobre 2009 12:45-13:45****WALLISER Bernard**(PSE) :__La révision des croyances multi-agents (avec JC Vergnaud et A Billot)__

**Jeudi 15 octobre 2009 12:45-13:45****WALLISER Bernard**(PSE) :__La révision des croyances multi-agents (avec JC Vergnaud et A Billot)__

**Jeudi 1er octobre 2009 12:45-13:45****FLECKINGER Pierre**(PSE) :__The Incentive Value of Deadlines__

**Jeudi 1er octobre 2009 12:45-13:45****FLECKINGER Pierre**(PSE) :__The Incentive Value of Deadlines__

**Jeudi 24 septembre 2009 12:45-13:45****MENAGER Lucie**(Paris 2) :__Intimidation strategies in competitive bidding__

**Jeudi 24 septembre 2009 12:45-13:45****MENAGER Lucie**(Paris 2) :__Intimidation strategies in competitive bidding__

**Jeudi 4 juin 2009 12:45-13:45****COLLIARD Jean-Edouard**(PSE) :__Competition between limit order markets and trading fees__

**Jeudi 28 mai 2009 12:45-13:45****MAILTAH George**(University of Pennsylvania) :__Common Learning in the Presence of Dependence__

**Jeudi 14 mai 2009 12:45-13:45****KRANTON Rachel**(University of Maryland) :__Networked Teams and Public Goods: Who Does the Work?__

**Jeudi 23 avril 2009 12:45-13:45****La séance a été annulée.****ALKAN Ahmet**(Sabanci University) :__Stable Matching Through Stable Shortlists__

**Jeudi 9 avril 2009 12:45-13:45****RENY Philip**(University of Chicago) :__On the Existence of Monotone Pure Strategy Equilibria in Bayesian Games.__- Texte intégral [pdf]

**Jeudi 2 avril 2009 12:45-13:45****La séance a été annulée.****PERONA Mathieu**(PSE) :__*__

**Jeudi 26 mars 2009 12:45-13:45****MIERENDORFF Konrad**(University of Bonn) :__Optimal Dynamic Mechanism Design with Deadlines__

**Jeudi 19 mars 2009 12:45-13:45****PICCOLO Salvator**(University of Salerno) :__Multiple-Bank Lending, Creditor Rights and Information Sharing.__- Texte intégral [pdf]

**Jeudi 5 mars 2009 12:45-13:45****GORDON Sidartha**(University of Montreal) :__Iteratively Stable Equilibria in Cheap Talk Games__

**Jeudi 26 février 2009 12:45-13:45****KUNIMOTO Takashi**(McGill University) :__Robust Virtual Implementation with Incomplete Information: Towards a Reinterpretation of the Wilson Doctrine__

**Jeudi 19 février 2009 12:45-13:45****SEKIGUCHI Tadashi**(Kyoto University) :__Repeated Games with Costly Imperfect Monitoring (joint with Eiichi Miyagawa and Yasuyuki Miyahara)__- Texte intégral [pdf]

**Jeudi 12 février 2009 12:45-13:45****MATHIS Jérôme**(TSE) :__Rating the Raters: Are Reputation Concerns Powerful enough to Discipline Rating Agencies?__

**Jeudi 5 février 2009 12:45-13:45****LAMBERT-MOGILIANSKY Ariane**(PSE) :__TI-games I: An Exploration of Type Indeterminacy in Strategic Decision-making__- Texte intégral [pdf]

**Jeudi 29 janvier 2009 12:45-13:45****DE CORNIERE Alexandre**(PSE) :__On the Optimal Design of a Search Engine's Advertising Platform__

**Jeudi 22 janvier 2009 12:45-13:45****BLOCH Francis**(Polytechnique) :__Optimal assignment of reassignable objects__

**Jeudi 15 janvier 2009 12:45-13:45****La séance a été annulée.****DE CORNIERE Alexandre**(PSE) :__On the Optimal Design of a Search Engine's Advertising Platform__

**Jeudi 11 décembre 2008 12:45-13:45****LOVO Stefano**(HEC) :__Belief-free Equilibria in Games with Incomplete Information: The N-player Case__

**Jeudi 4 décembre 2008 12:45-13:45****ETTINGER David**(Univ. Cergy) :__Deception in a Repeated Expert/Agent Interaction: Theory and Experiment__

**Jeudi 27 novembre 2008 12:45-13:45****OYAMA Daisuke**(Hitotsubashi Univ.) :__On Ex Post Individually Rational Partnership Dissolution__

**Jeudi 13 novembre 2008 12:45-13:45****NUNEZ Matias**(Ecole polytechnique) :__A Study of Approval Voting on Large Poisson Games__

**Jeudi 23 octobre 2008 12:45-13:45****La séance a été annulée.****PICCOLO Salvatore**(Univ. of Salerno) :__The strategic value of quantity forcing contracts__

**Jeudi 16 octobre 2008 12:45-13:45****CASELLA Alessandra**(Columbia Univ.) :__Storable Votes and Agenda Control. Theory and Experiments__

**Jeudi 2 octobre 2008 12:45-13:45****LAMY Laurent**(PSE) :__Mechanism Design with Partially-Specified Participation Games__

**Jeudi 18 septembre 2008 12:45-13:45****FALLY Thibault**(PSE) :__Global Sourcing under imperfect capital markets__

**Jeudi 29 mai 2008 12:45-13:45****DENG X.**(City univ. of Hong Kong) :__Sales of Clicks and Auction Theory__- RésuméSponsored search has become a principal source of revenue for search engine companies. The business model relies on advertisement sales that provide advertisers opportunities to introduce their products directly to potential customers. Pricing of such advertising positions has been vitally important for the search engines. The generalized second price auction has turned out to be the primary protocol for such sponsored search markets. While several Nash equilibria may exist for the generalized second price auction, we propose the concept of the forward looking Nash equilibrium as the bidder's individual rational manipulation outcome. We further identify and focus on traffic arbitrage and click arbitrage possibilities crossing multiple markets as well as derive and characterize equilibria across markets.

**Jeudi 15 mai 2008 12:45-13:45****KOESSLER F.**(PSE) :__Multidimensional Communication Mechanisms: Cooperative and Conflicting Designs__**Co-auteur : D. Martimort**- Texte intégral [pdf]

**Jeudi 17 avril 2008 12:45-13:45****La séance a été annulée.****KOESSLER Frédéric**(PSE) :__Multidimensional Communication Mechanisms: Cooperative and Conflicting Designs__**David Martimort**

**Jeudi 10 avril 2008 12:45-13:45****VAN DER STRAETEN Karine**(PSE) :__A Communication Game on Electoral Platforms__**Gabrielle Demange**

**Jeudi 20 mars 2008 12:45-13:45****DESSEIN W.**(Univ. of Chicago) :__Organize to Compete__**R. Alonso and N. Matouschek**

**Jeudi 21 février 2008 12:45-13:45****MOIZEAU F.**(Toulouse School of Economics) :__Dynamic Regulation of Quality__

**Jeudi 14 février 2008 12:45-13:45****La séance a été annulée.****LAMBERT-MOGILIANSKY A.**(PSE) :__*__

**Jeudi 31 janvier 2008 12:45-13:45****GOSSNER O.**(PSE) :__Efficiency in repeated prisoner's dilemma without conditional independence__**Co-auteurs : K. Fong, J. Horner, et Y. Sannikov**

**Jeudi 24 janvier 2008 12:45-13:45****BIRAN O.**(Univ. de Paris 9) :__Efficiency and the Final Consumer in Resale Markets with Externalities__

**Jeudi 10 janvier 2008 12:45-13:45****OURY M.**(PSE) :__Continuous Implementation__**Co-auteur : O. Tercieux**- Texte intégral [pdf]

**Jeudi 20 décembre 2007 12:45-13:45****RAYO L.**(Univ. of Chicago) :__Status, Market Power, and Veblen Effects__**Co-auteurs : Miguel Diaz, Haresh Sapra**- Texte intégral [pdf]

**Jeudi 13 décembre 2007 12:45-13:45****SAURI ROMERO L.**(European univ. institute) :__Parallel trade and incentives to innovate when governments decide on prices__

**Jeudi 29 novembre 2007 12:45-13:45****RENAULT R.**(Univ. de Cergy-Pontoise) :__Gathering and disseminating information in discrete choice models__

**Jeudi 15 novembre 2007 12:45-13:45****HAGENBACH J.**(Univ. de Paris 1) :__Strategic Communication Networks__

**Jeudi 25 octobre 2007 12:45-13:45****COMOLA M.**(Univ. Pompeu Fabra) :__The Network Structure of Informal Arrangements : Evidence from Rural Tanzania__

**Jeudi 4 octobre 2007 12:45-13:45****MIERENDORFF K.**(Univ. Bonn) :__An efficient Intertemporal Auction__

**Jeudi 14 juin 2007 12:45-13:45****SCHULTZ N.**(PSE) :__Anticompetitive Vertical Mergers Waves__**Co-auteur (s) : J. Hombert et J. Pouyet**- RésuméWe develop an equilibrium model of vertical mergers. We show that, when a wave of mergers removes all upstream firms, the competitive forces on the upstream market may collapse. Indeed, when an integrated firm supplies the upstream market, it internalizes the fact that customers lost on the downstream market can be recovered via the upstream market. Thus, the upstream supplier charges higher downstream prices. Its integrated rivals benefit from this behavior, they may therefore not undercut on the upstream market. This mechanism leads to anticompetitive waves of mergers. Journal of Economic Literature Classification Number: L22, L13, L42. Keywords: vertical merger, vertical integration, foreclosure.
- Texte intégral [pdf]

**Jeudi 7 juin 2007 12:45-13:45****AUSUBEL L. M.**(Univ. of Maryland) :__Walrasian Tatonnement for Discrete Goods__

**Jeudi 24 mai 2007 12:45-13:45****TAKAHASHI S.**(Harvard univ.) :__Community Enforcement when Players Observe Partners’ Past Play__- RésuméI investigate whether a community can sustain cooperation in the repeated prisoner’s dilemma by having cheaters sanctioned not by their victims but by third parties. Motivated by systems of credit history recording, online feedback systems, and some experimental settings, I assume that players can access information about their partners’ past play for free, but that acquiring information about their partners’ past partners’ past play is prohibitively costly. In this setting, even though players cannot distinguish cheaters from those who punish cheaters, I show that any level of cooperation can be sustained by an equilibrium. The equilibrium I construct has the following two properties: every player chooses his actions independently of his own record of play, and he is indifferent between cooperation and defection at all histories. This equilibrium carries over to the finite-population setting and is robust to noise in the process of choosing actions or of recording past play. The technique of equilibrium construction is applied to more general stage games. I also analyze the possibility of cooperation either when players are required to have strict incentives to follow equilibrium strategies or when only summary statistics of records are stored in the community.
- Texte intégral [pdf]

**Jeudi 10 mai 2007 12:45-13:45****ROEMER J. E.**(Yale univ.) :__The political economy of income taxation in a two-party democracy__- RésuméParties compete on a large policy space. Only a fraction of each voter type will vote for each party, perhaps because of party reputations, or issues not modeled here. Each party’s policy makers comprise two factions, one concerned with maximizing the welfare of its constituency, the other with maximizing vote share. These factions are particularly concerned with the party’s base or core voters and the swing voters, respectively. All these concepts (constituency, core, swing) are endogenous to the policy choice. An application to competition over redistribution produces equilibria in which each party proposes a piece-wise linear tax schedule, and these schedules coincide in their treatment of a possibly large interval of middle-income voters. This appears to conform with recent tax history in the US.
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**Jeudi 26 avril 2007 12:45-13:45****BOS O.**(PSE) :__Charity Auctions for the Happy Few__- RésuméRecent literature has shown that all-pay auctions raise more money for charity than winnerpay auctions. We demonstrate that the first and second-price winner-pay auctions outperform first-price all-pay auctions when bidders are sufficiently asymmetric. To prove it, we consider a framework with complete information. This analysis is relevant for two main reasons. On the one hand, complete information is more realistic and corresponds to events which occur for instance in a local service club (like in a voluntary organization) or in a show business dinner. Potential bidders are acquaintances or know one another well. On the other hand, our model keeps the qualitative predictions of a private value model under incomplete information in which bidders are ex ante asymmetric that is to say different bidders’ values are drawn from different distributions. Furthermore, we also analyze second-price all-pay auction. Finally, we show that individual minimum bids could improve the relative revenue performance of first-price allpay compared to first-price winner-pay auction. Keywords: All-pay auctions, charity, complete information, externalities JEL Classification: D44, D62, D64

**Jeudi 5 avril 2007 12:45-13:45****LAURENT R. A.**(PSE) :__Duopole avec biens d'expérience et consommateurs raisonnant par similarité__- RésuméDeux firmes sont présentes sur le marché d’un bien d’expérience mais ne peuvent signaler leur "qualité". L’utilité nette attendue d’un bien par les consommateurs dépend de leur degré d’exigence et d’une information privée, plus ou moins précise. Ces consommateurs choisissent le bien qui maximise l’utilité nette pondérée par la similarité entre l’information privée et le bien considéré : ce critère de décision est une version simplifiée et statique de la "Case-Based Decision Theory" (Gilboa et Schmeidler, 1995). L’introduction des prix dans cette règle de décision permet d’établir des fonctions de demande dans un cadre spatial. Cet article montre qu’un équilibre de Nash en prix existe en fonction de la forme de l’utilité nette et du degré d’asymétrie des coûts. Lorsque les consommateurs sont peu exigeants, la différenciation est purement horizontale : chaque firme sert les consommateurs informés sur son bien. Si les consommateurs sont relativement exigeants, une dimension verticale est introduite dans la différenciation : la firme vendant le bien le moins apprécié choisit un prix faible et attire les consommateurs dont l’information est la moins précise. Les autres consommateurs achètent le bien concurrent. Toutefois, si les consommateurs sont très exigeants, cette dimension verticale disparaît. classification jel : D11, D43, L13. mots clés : différenciation des produits, oligopole, biens d’expérience, information privée, théorie de la décision à base de cas.
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**Jeudi 29 mars 2007 12:45-13:45****CHASSANG S.**(MIT) :__Fear of miscoordination and the robustness of cooperation in dynamic global games with exit__- RésuméThis paper develops a framework to assess the impact of miscoordination fear on agents' ability to sustain dynamic cooperation. Building on theoretical insights from Carlsson and van Damme (1993), it explores the effect of small amounts of private information on a class of dynamic cooperation games with exit. It is shown that lack of common knowledge creates a fear of miscoordination which pushes players away from the full-information Pareto frontier. Unlike in one-shot two-by-two games, the global games information structure does not yield equilibrium uniqueness, however, by making it harder to coordinate, it does reduce the range of equilibria and gives bite to the notion of local dominance solvability. Finally, the paper provides a simple crite- rion for the robustness of cooperation to miscoordination fear, and shows it can yield predictions that are qualitatively different from those obtained by focusing on Pareto effcient equilibria under full information. keywords: cooperation, strategic risk, miscoordination risk, global games, dy- namic games, exit games, rationalizability, local strong rationalizability, local domi- nance solvability. Jel classification codes: C72, C73
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**Jeudi 8 mars 2007 12:45-13:45****VERDIER M.**(ENST) :__Interchange fees and incentives to invest in the quality of a payment card system__- RésuméIn this paper, I analyse the optimal interchange fee in a payment card system where two monopoly banks have the possibility to invest in quality to raise the transaction volume. I model quality as a sum of specific investments from the cardholder's bank (the Issuer) and the merchant's bank (the Acquirer), and I assume that investments impact di¤erently the consumer and the merchant side. If the level of quality is exogenous, I prove that it is optimal for the payment platform to set an interchange fee equal to the Acquirer's margin. I extend Baxter (1983)'s model by proving that the optimal interchange fee depends on the level of quality of the payment system. However, if banks have the possibility to invest in quality, and if the perception of quality improvements is higher on the consumer side, the optimal interchange fee can be lower than the Acquirer's margin. This is because the interchange fee and the Acquirer's investments are strategic substitutes. If investments impact relatively more the merchant side, the optimal interchange fee remains equal to the Acquirer's margin. JEL Codes: G21, L31, L42. Keywords: Payment card systems, interchange fee, two-sided markets, investments in quality.
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**Jeudi 15 février 2007 12:45-13:45****LAMBERT-MOGILIANSKI A.**(PSE) :__Système non-classique et rationalité limitée__**Co-auteur (s) : V. I. Danilov**- RésuméIndividual choices often depend on the order in which decisions are made, i.e., they exhibit non-commutativity. In this paper, we expose a general theory of measurable systems (an example of which is an individual’s preferences) allowing for incompatible (non-commuting) measurements. The basic concepts are illustrated in an example of non-classical rational choice. We conclude with a discussion of some of the basic properties of non-classical systems in the context of social sciences. In particular, we argue that the distinctive feature of non-classical systems translates into a formulation of bounded rationality. JEL: D80, C65, B41 keywords: non-classical system, incompatible measurement, orthospace, state, properties.
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**Jeudi 8 février 2007 12:45-13:45****LEGER P. T.**(HEC) :__Provider Competition in a Dynamic Setting__**Co-auteur (s) : M. Allard & L. Rochaix**- RésuméIn this paper, we examine provider and patient behaviour where effort is non-contractible and competition between providers is modeled in an explicit way. More specifically, we construct a model where physicians repeatedly compete for patients and where patients' outside options are solved for in equilibrium. In our model, physicians are characterized by an individual-specific ethical constraint which allows for unobserved heterogeneity in the physicians market. Allowing for unobserved heterogeneity in the physicians market introduces uncertainty in the patient's expected treatment if he were in fact to leave his current physician to seek care elsewhere. We also introduce switching costs associated with moving from one physician to another and, un- certainty in the treatment-outcome relationships. Our model can generate equilibria which are consistent with real-world observations. That is, our model can generate treatment heterogene- ity, unstable physician-patient relationships and, over-treatment (a form of defensive medicine). Our model also suggests several avenues which may lead to more e¢ cient provision of care. JEL classification: I10, I18, J24, C30 Keywords: Physician Payment Mechanisms, Physician heterogeneity, Competition, Information Asymmetry, Insurance.
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**Jeudi 25 janvier 2007 12:45-13:45****CHASSAGNON A.**(PSE) :__On moral hazard and non exclusive contracts__

**Jeudi 11 janvier 2007 12:45-13:45****MENONI B.**(Centre de recherche en économie et statistique) :__Decision making with doubt regarding the consequences of an action__- RésuméAnscombe & Aumann (1963) improved the model developed by von Neumann & Morgenstern (1944) suggesting that the outcome of an act can be a lottery. They showed that if the preference relation of a decision maker obeys several axioms then the latter behaves as if they were maximizing some expected utility. We slightly depart from their definition of acts and consider that, in a given state of Nature, the result of an act is a possibility distribution over outcomes rather than a probability distribution. We then extend the work by ? to a more general setting. One can consider our contribution as a refinement of a model developed by Ghirardato (2001): the latter models the consequence of an act as a list of possible outcomes. We add to the list of possible outcomes some structure, namely a qualitative structure. We show that if the preference relation a decision maker may have obeys several restrictions, their choices ensue from the maximization of a – qualitative – expected utility. Keywords: Decision making, ordinal representation, possibility theory. JEL Classification: D81, D83, D89.
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**Jeudi 21 décembre 2006 11:00-12:00****WEYL G.**(Princeton univ.) :__The Price Theory of Two-Sided Markets__- RésuméI establish a number of baseline positive and normative results in the price theory of two-sided markets building on the work of Rochet and Tirole (2003). On the positive side, I introduce the notion of vulnerability of demand to separate previously confounded effects. I find that competition, price controls and subsidies always reduce the price level, defined as the sum of prices on the two sides of the market. However, price controls and competition that are “unbalanced” may raise prices on one side of the market. The normative analysis emphasizes the importance of externalities across the two sides of the market and their impact on socially optimal pricing. The socially optimal price level, which takes an intuitive Ramsey-pricing form, is always below cost. Subsidies may be desirable even if the profits of the firm are disregarded. In determining optimal price balance, seemingly similar welfare criteria generally conflict. Consumers on one side of the market may want to make transfers to the other side in order to thicken their pool of partners. Unbalanced competition that undermines such transfers may harm all parties. A number of implications for policy are discussed.
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**Jeudi 7 décembre 2006 12:45-13:45****LAMY L.**(Laboratoire d'économie industrielle) :__Order Independent Individual Rationality__- RésuméWe consider the implementation of an economic outcome under complete information when the principal cannot commit to a simultaneous participation game. From a class of sequential participation games, we introduce the concept of implementability under order independent individual rationality. We characterize the set of implementable mechanisms, which is possibly a non-convex set, and we solve the optimal design program: the principal raises a lower revenue but economic efficiency is not damaged.
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**Jeudi 23 novembre 2006 12:45-13:45****NIKOLOVA R.**(Laboratoire d'économie industrielle) :__Incentives, markets and knowledge based hierarchies__

**Jeudi 16 novembre 2006 12:45-13:45****DESGRANGES G.**(THEMA) :__Strongly Rational Expectations Equilibria, Endogenous Acquisition of Information and the Grossman-Stiglitz Paradox__**Co-auteur (s) : M. Heinemann**- RésuméStrongly Rational Expectations Equilibria, Endogenous Acquisition of Information and the Grossman-Stiglitz Paradox Abstract: This paper analyzes conditions for existence of a strongly rational expectations equilibrium (SREE) in models with private information where the amount of private information is endogenously determined and where the price transmits relevant information to market participants. It is shown that the conditions for existence of a SREE known from models with exogenously given private information have to be qualified if private information is endogenously determined. A SREE exists only if informativeness of the market price falls short of a specific lower bound, which depends on the properties of the cost function associated with the individual acquisition of information. This upper bound is generally lower than that valid in case of exogenously given information. An interpretation that links our results to the famous Grossman-Stiglitz Paradox is also given.
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**Jeudi 19 octobre 2006 12:45-13:45****LAURENT R.A.**(PSE) :__Differentiated Duopoly with Elimination By Aspects__- RésuméElimination by aspects (EBA) is a discrete model of probabilistic choice worked out by Tversky in 1972 which supposes that decision makers follow a particular heuristic during a process of sequential choice. Goods are described by their attributes and, at each decision stage, consumers eliminate all the products not having an expected specific attribute, until only one option remains. In this paper, probabilities resulting from the EBA model are used to construct demands of a differentiated duopoly with imperfectly rational consumers. These demands are also consistent with partial heterogeneity of preferences and may be linked with a spatial framework in which consumers have convex perception of distance. In this model, a price Nash equilibrium in pure strategies exists under two conditions on attributes level and unit costs. At the outcome, the “differentiation by attributes” constitutes a general framework which embodies both horizontal and vertical differentiation. When the equilibrium does not exist, the interaction of best response functions of the firms induces an Edgeworth cycle instead of an exit of the lowest attributes level firm. This result underlines the role of cost asymmetries in the existence of such a cycle.
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**Jeudi 12 octobre 2006 12:45-13:45****SIMULA L.**(PSE) :__Optimal Nonlinear Income Tax when Highly Skilled Vote with their Feet__**Co-auteur (s) : A. Trannoy**- RésuméThis paper examines how allowing individuals to emigrate to pay lower taxes changes the optimal non-linear income tax scheme in a Mirrleesian economy. Type-dependent participation constraints are borrowed from contract theory. An individual emigrates if his domestic utility is less than his utility abroad net of migration costs, utilities and costs both depending on productivity. Three social criteria are distinguished according to the agents whose welfare matters. Mobility significantly alters the closed-economy results qualitatively, but also quantitatively as verified by simulations. A curse of the middle-skilled occurs in the first-best. In the second-best, the middle-skilled can support the highest average tax rates and the marginal tax rates can be negative. Moreover, preventing emigration of the highly-skilled is not necessarily optimal.
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**Jeudi 21 septembre 2006 12:45-13:45****KETS W.**(Tilburg univ.) :__Learning to be Prepared__**Co-auteur : Mark Voorneved**- RésuméBehavioral economics provides several motivations for the common observation that agents appear somewhat unwilling to deviate from recent choices. More recent choices can be more salient than other choices, or more readily available in the agent’s mind. Alternatively, agents may have formed habits, use rules of thumb, or lock in on certain modes of behavior as a result of learning by doing. This paper provides discrete-time adjustment processes for strategic games in which players display precisely such a bias towards recent choices. In addition, players choose best replies to beliefs supported by observed play in the recent past, in line with much of the literature on learning. These processes eventually settle down in the minimal prep sets of Voorneveld (2004, 2005).
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**0000**- campus Jourdan, 48 boulevard Jourdan, 75014 Paris
**BASTIANELLO Lorenzo**(Paris 1) :__Target-based solutions for Nash bargaining__- RésuméAbstract. We revisit the Nash model for two-person bargaining. A mediator knows agents' ordinal preferences over feasible proposals, but has incomplete information about their acceptance thresholds. We provide a behavioural characterisation under which the mediator recommends a proposal that maximises the probability that bargainers strike an agreement. Some major solutions are recovered as special cases; in particular, we o ffer a straightforward interpretation for the product operator underlying the Nash solution.

**0000**- Campus Jourdan, bâtiment G, 1er étage, salle de réunions
**REDLICKI Bartosz**(U of Cambridge) :__*__

**0000****RIVERA Thomas**:__Incentives and the Structure of Communication__- RésuméThis paper analyzes the incentives that arise within an organization when communication is restricted to a particular network structure (e.g., a hierarchy). We show that restricting communication between the principal and agents may create incentives for the agents to misbehave when transmitting information and tasks throughout the organization. Such incentives can render the principal's most preferred outcome infeasible and therefore introduces a trade off between the cost of communication borne by the principal and the benefit of curbing incentives to deviate induced by the communication structure. To remedy this issue, we provide necessary and sufficient conditions on the topology of the network of communication such that restricting communication to a particular network does not restrict the set of outcomes that the principal could otherwise achieve. In this sense, we show that for any underlying incentives and any outcome available when communication is unrestricted, there exists a (finite) communication scheme restricted to a particular network that implements this outcome (i.e., does not induce agents to misbehave in the communication phase) if and only if that network satisfies our conditions.