GORDON Sidartha

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We introduce a neighborhood structure in a waiting game, where the payoff of stopping increases each time a neighbor stops. We show that the dynamic evolution of the network depends on initial parameters and can take the form of either a shrinking network, where players at the edges stop first, or a fragmenting network where interior players stop first. We find that, in addition to the coordination inefficiency standard in waiting games, the neighborhood structure gives rise to two other inefficiencies, the first linked to the order of exit and the second to the final distribution of remaining nodes.

In many situations, decision-makers have to choose an action or a policy without being fully informed. In addition, it may be difficult or expensive to acquire missing information directly. In such cases, they may seek help from informed institutions or individuals. The latter may try to influence the decision in their favor by hiding or presenting only part of the information. For example, employers rely on information presented by job seekers, financial authorities use company reports to evaluate them, and elected officials consult experts before proposing legislation. In these examples, at least some information is certifiable or verifiable. In other words, the informed party can prove certain statements by presenting evidence, or the policymaker can verify the accuracy of those statements. Because verification can be costly or time-consuming, the decision-maker can often verify only a portion of the information received. These constraints determine the amount of information that can be verified before the decision is made. The first two chapters focus on models adapted to situations where the decision maker must evaluate a statement or respond to a request made by an individual or institution. In the third chapter, I consider a slightly different setting where the decision maker consults informed agents before choosing an action.In the first chapter, I study a model where the preferences of the informed agent are state independent. In one-way communication, only the agent sends a message to the decision maker. In two-way communication, both exchange messages. I compare these two mechanisms by assuming that the same amount of evidence can be presented in both cases. In the canonical two-way communication mechanism, after receiving a statement from the agent, the decision maker asks the agent to present a particular piece of evidence. The decision depends only on his ability to present the requested evidence. The main result of this chapter states that two-way communication improves the outcome if the certification of information is limited in a way that prevents the decision maker from reaching his optimum in one-way communication.The second chapter, which results from joint work with Frédéric Koessler (CNRS, Paris School of Economics), studies the implementation in the presence of ambiguity averse agents. We show that if an allocation rule can be implemented with unlimited certification, it can also be implemented with limited information certification if the decision maker can use ambiguous communication mechanisms and if the agents are ambiguity averse in the sense of maxmin. The opposite implication is true if there is a single agent and a punishing action.In the third chapter, I study a model with two types of informed agents. One type wants to maximize the decision maker's action while the other wants to minimize it. In this case, there may be a need to consult more than one agent. I study sequential consultation and examine its impact on information revelation. In equilibrium, the decision maker continues to consult informed agents as long as her uncertainty is high enough. Minority agents - in terms of preferences - can influence the decision maker by withholding information when it is unfavorable because he rightly anticipates that the majority is more likely to do so. In addition, the threat of sequential consultation can be used to extract more accurate information while consulting with a single agent.

We examine project selection decisions of firms constrained in the number of projects they can handle at once. A new project opportunity arises every period. Taking on a project requires a commitment of uncertain duration, preventing the firm from selecting another project in subsequent periods until the commitment ends. In our dynamic game, when two firms are free of commitment, they move sequentially in random order. Symmetric pure strategy Markov perfect equilibria always exist. In equilibrium, the first mover strategically rejects some projects that are then selected by the second mover, even when the value of the project is the same for both firms. A monopolist rejects more projects, and adopts ones of higher average quality compared to the duopolist. Duopolists select too few projects compared to their jointly optimal behavior. We extend the model to allow for externalities, asymmetry, and n>2n>2 firms.

We consider a conflict under incomplete information where two opponents fight to impose their preferred policy. Before the conflict, one opponent (the agent) trusts the information received by his principal. Under some conditions, the principal induces hawkish attitudes in the agent: the agent never doubts the optimality of his preferred policy, conflicts are violent, and bad decisions are sometimes made. Under other conditions, the agent believes that his opponent may be right, even when all evidence indicates that the policy preferred by the opponent is certainly suboptimal. In this case, the agent adopts dovish attitudes and conflicts are less violent.

We introduce a "nestedness" relation for a general class of sender-receiver games and compare equilibrium properties, in particular the amount of information transmitted, across games that are nested. Roughly, game is nested in game if the players's optimal actions are closer in game. We show that under some conditions, more information is transmitted in the nested game in the sense that the receiver's expected equilibrium payoff is higher. The results generalize the comparative statics and welfare comparisons with respect to preferences in the seminal paper of Crawford and Sobel (1982). We also derive new results with respect to changes in priors in addition to changes in preferences. We illustrate the usefulness of the results in three applications: (i) delegation to an intermediary with a different prior, the choice between centralization and delegation, and two-way communication with an informed principal.

Conflicts are likely less violent if individuals entertain the possibility that the opponent may be right. Why is it so difficult to observe this attitude? In this paper, we consider a game of conflict where two opponents fight in order to impose their preferred policy. Before entering the conflict, one opponent (the agent) trusts the information received by his principal. The principal wants to a↵ect the agent's e↵ort, but he also cares that the agent selects the correct policy and that he has the right incentives to acquire information.We find conditions under which the principal induces hawkish attitudes in the agent. As a result, the agent has no doubts about the optimality of his preferred policy, conflicts are violent and bad decisions are sometimes made. Under some other conditions, the agent adopts dovish attitudes of systematic doubt and conflicts are less violent.

We provide several characterizations of unanimity decision rules, in a public choice model where preferences are constrained by attributes possessed by the alternatives (Nehring and Puppe, 2007a,b). Solidarity conditions require that when some parameters of the economy change, the agents whose parameters are kept fixed either all weakly lose or they all weakly win. Population-monotonicity (Thomson, 1983a,b) applies to the arrival and departure of agents, while replacement-domination (Moulin,1987) applies to changes in preferences. We show that either solidarity property is compatible with voter-sovereignty and strategy-proofness if and only if the attribute space is quasi-median (Nehring, 2004), and with Pareto-efficiency if and only if the attribute space is a tree. Each of these combinations characterizes unanimity.

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We study mechanisms for selecting up to m out of n projects. Project managers’ private information on quality is elicited through transfers. Under limited liability, the optimal mechanism selects projects that maximize some function of the project’s observable and reported characteristics. When all reported qualities exceed their own project-specific thresholds, the selected set only depends on observable characteristics, not reported qualities. Each threshold is related to (i) the outside option level at which the cost and benefit of eliciting information on the project cancel out and (ii) the optimal value of selecting one among infinitely many ex ante identical projects.

We provide several characterizations of unanimity decision rules, in a public choice model where preferences are constrained by attributes possessed by the alternatives (Nehring and Puppe, 2007a,b). Solidarity conditions require that when some parameters of the economy change, the agents whose parameters are kept fixed either all weakly lose or they all weakly win. Population-monotonicity (Thomson, 1983a,b) applies to the arrival and departure of agents, while replacement-domination (Moulin,1987) applies to changes in preferences. We show that either solidarity property is compatible with voter-sovereignty and strategy-proofness if and only if the attribute space is quasi-median (Nehring, 2004), and with Pareto-efficiency if and only if the attribute space is a tree. Each of these combinations characterizes unanimity.

We study mechanisms for selecting up to m out of n projects. Project managers' private information on quality is elicited through transfers. Under limited liability, the optimal mechanism selects projects that maximize some function of the project's observable and reported characteristics. When all reported qualities exceed their own project-specific thresholds, the selected set only depends on observable characteristics, not reported qualities. Each threshold is related to (i) the outside option level at which the cost and benefit of eliciting information on the project cancel out and (ii) the optimal value of selecting one among infinitely many ex ante identical projects.

We consider collective decision problems given by a profile of single-peaked preferences defined over\ud the real line and a set of pure public facilities to be located on the line. In this context, Bochet and Gordon\ud (2012) provide a large class of priority rules based on efficiency, object-population monotonicity and\ud sovereignty. Each such rule is described by a fixed priority ordering among interest groups. We show that\ud any priority rule which treats agents symmetrically — anonymity — respects some form of coherence\ud across collective decision problems — reinforcement — and only depends on peak information — peakonly\ud — is a weighted majoritarian rule. Each such rule defines priorities based on the relative size of the\ud interest groups and specific weights attached to locations. We give an explicit account of the richness of\ud this class of rules.

We introduce a "nestedness" relation for a general class of sender-receiver games and compare equilibrium properties, in particular the amount of information transmitted, across games that are nested. Roughly, game is nested in game if the players's optimal actions are closer in game. We show that under some conditions, more information is transmitted in the nested game in the sense that the receiver's expected equilibrium payoff is higher. The results generalize the comparative statics and welfare comparisons with respect to preferences in the seminal paper of Crawford and Sobel (1982). We also derive new results with respect to changes in priors in addition to changes in preferences. We illustrate the usefulness of the results in three applications: (i) delegation to an intermediary with a different prior, the choice between centralization and delegation, and two-way communication with an informed principal.