We analyze games of incomplete information and offer equilibrium predictions which are valid for, and in this sense robust to, all possible private information structures that the agents may have. We completely characterize the set of Bayes correlated equilibria in a class of games with quadratic payoffs and normally distributed uncertainty in terms of restrictions on the first and second moments of the equilibrium action-state distribution. We derive exact bounds on how prior knowledge about the private information refines the set of equilibrium predictions.
We consider information sharing among firms under demand uncertainty and find newly optimal information policies via the Bayes correlated equilibria. Finally, we reverse the perspective and investigate the identification problem under concerns for robustness to private information. The presence of private information leads to set rather than point identification of the structural parameters of the game.
We analyze games of incomplete information and offer equilibrium predictions which are valid for all possible private information structures that the agents may have. Our characterization of these robust predictions relies on an epistemic result which establishes a relationship between the set of Bayes Nash equilibria and the set of Bayes correlated equilibria.
We completely characterize the set of Bayes correlated equilibria in a class of games with quadratic payoffs and normally distributed uncertainty in terms of restrictions on the first and second moments of the equilibrium action-state distribution. We derive exact bounds on how prior information of the analyst refines the set of equilibrium distribution. As an application, we obtain new results regarding the optimal information sharing policy of firms under demand uncertainty.
Finally, we reverse the perspective and investigate the identification problem under concerns for robustness to private information. We show how the presence of private information leads to partial rather than complete identification of the structural parameters of the game. As a prominent example we analyze the canonical problem of demand and supply identification.
We analyze games of incomplete information and offer equilibrium predictions which are valid for, and in this sense robust to, all possible private information structures that the agents may have. We completely characterize the set of Bayes correlated equilibria in a class of games with quadratic payoffs and normally distributed uncertainty in terms of restrictions on the first and second moments of the equilibrium action-state distribution. We derive exact bounds on how prior knowledge about the private information refines the set of equilibrium predictions.
We consider information sharing among firms under demand uncertainty and find newly optimal information policies via the Bayes correlated equilibria. Finally, we reverse the perspective and investigate the identification problem under concerns for robustness to private information. The presence of private information leads to set rather than point identification of the structural parameters of the game.
We analyze games of incomplete information and offer equilibrium predictions which are valid for, and in this sense robust to, all possible private information structures that the agents may have. The set of outcomes that can arise in equilibrium for some information structure is equal to the set of Bayes correlated equilibria. We completely characterize the set of Bayes correlated equilibria in a class of games with quadratic payoffs and normally distributed uncertainty in terms of restrictions on the first and second moments of the equilibrium action-state distribution. We derive exact bounds on how prior knowledge about the private information refines the set of equilibrium predictions.
We consider information sharing among firms under demand uncertainty and find new optimal information policies via the Bayes correlated equilibria. We also reverse the perspective and investigate the identification problem under concerns for robustness to private information. The presence of private information leads to set rather than point identification of the structural parameters of the game.
This essay is the introduction for a collection of papers by the two of us on “Robust Mechanism Design” to be published by World Scientific Publishing. The appendix of this essay lists the chapters of the book.
The objective of this introductory essay is to provide the reader with an overview of the research agenda pursued in the collected papers. The introduction selectively presents the main results of the papers, and attempts to illustrate many of them in terms of a common and canonical example, the single unit auction with interdependent values.
In addition, we include an extended discussion about the role of alternative assumptions about type spaces in our work and the literature, in order to explain the common logic of the informational robustness approach that unifies the work in this volume.
A universal type space of interdependent expected utility preference types is constructed from higher-order preference hierarchies describing (i) an agent’s (unconditional) preferences over a lottery space; (ii) the agent’s preference over Anscombe-Aumann acts conditional on the unconditional preferences; and so on.
Two types are said to be strategically indistinguishable if they have an equilibrium action in common in any mechanism that they play. We show that two types are strategically indistinguishable if and only if they have the same preference hierarchy. We examine how this result extends to alternative solution concepts and strategic relations between types.
A universal type space of interdependent expected utility preference types is constructed from higher-order preference hierarchies describing (i) an agent’s (unconditional) preferences over a lottery space; (ii) the agent’s preference over Anscombe-Aumann acts conditional on the unconditional preferences; and so on.
Two types are said to be strategically indistinguishable if they have an equilibrium action in common in any mechanism that they play. We show that two types are strategically indistinguishable if and only if they have the same preference hierarchy. We examine how this result extends to alternative solution concepts and strategic relations between types.
We identify a universal type space of possible interdependent (expected utility) preferences of a group of agents satisfying two criteria. First, a type consists of a “detail free” description, in a natural language, of the agents’ interdependent preferences. Second, distinct types in the universal type space must be “strategically distinguishable” in the sense that there must exist a mechanism where those types are guaranteed to behave differently in equilibrium.
Our results generalize and unify results of Abreu and Matsushima (1992b) (who characterized strategic distinguishability on fixed finite type spaces) and Dekel, Fudenberg, and Morris (2006), (2007) (who characterized strategic distinguishability on type spaces without preference uncertainty and thus without interdependent preferences).
We study agents whose expected utility preferences are interdependent for informational or psychological reasons. We characterize when two types can be “strategically distinguished” in the sense that they are guaranteed to behave differently in some finite mechanism. We show that two types are strategically distinguishable if and only if they have different hierarchies of interdependent preferences. The same characterization applies for rationalizability, equilibrium, and any interim solution concept in between. Our results generalize and unify results of Abreu and Matsushima (1992), who characterize strategic distinguishability on fixed finite type spaces, and Dekel, Fudenberg, and Morris (2006), (2007), who characterize strategic distinguishability without interdependent preferences.
This note studies (full) implementation of social choice functions under complete information in (correlated) rationalizable strategies. The monotonicity condition shown by Maskin (1999) to be necessary for Nash implementation is also necessary under the more stringent solution concept. We show that it is also sufficient under a mild “no worst alternative” condition. In particular, no economic condition is required.
We consider the implementation of social choice functions under complete information in rationalizable strategies. A strict (and thus stronger) version of the monotonicity condition introduced by Maskin (1999) is necessary under the solution concept of rationalizability. Assuming the social choice function is responsive (i.e., it never selects the same outcome in two distinct states), we show that it is also sufficient under a mild “no worst alternative” condition. In particular, no economic condition is required. We also discuss how our results extend when the social choice function is not responsive.