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.

We study a strict version of the notion of equilibrium robustness by Kajii and Morris (1997) that allows for a larger class of incomplete information perturbations of a given complete information game, where with high probability, players believe that their payoffs are close to (but may be different from) those of the complete information game. We show that a strict monotone potential maximizer of a complete information game is strictly robust if either the game or the associated strict monotone potential is supermodular, and that the converse also holds in all binary-action supermodular games.

This note demonstrates how the insights from Morris et al. (2020) can be applied to the problem of optimal joint design of information and transfers in team production.

The third essay, co-written with Drew Fudenberg and David K. Levine, provides a characterization of the limit set of perfect public equilibrium payoffs of repeated games with imperfect public monitoring as the discount factor goes to one. Our result covers general stage games including those that fail a "full-dimensionality" condition that had been imposed in past work. It also provides a characterization of the limit set when the strategies are restricted in a way that endogenously makes the full-dimensionality condition fail, as in the strongly symmetric equilibrium studied. Finally, we use our characterization to give a sufficient condition for the exact achievability of first-best outcomes.

Generalized notions of potential maximizer, monotone potential maximizer (MP-maximizer) and local potential maximizer (LP-maximizer), are studied. It is known that 2x2 coordination games generically have a potential maximizer, while symmetric 4x4 supermodular games may have no MP- or LP-maximizer. This note considers the case inbetween, namely the class of (generic) symmetric 3x3 supermodular coordination games. This class of games are shown to always have a unique MP-maximizer, and its complete characterization is given. A nondegenerate example demonstrates that own-action quasiconcave supermodular games may have more than one LP-maximizers.

This paper studies equilibrium selection in binary supermodular games based on perfect foresight dynamics. We provide complete characterizations of absorbing and globally accessible equilibria and apply them to two subclasses of games. First, for unanimity games, it is shown that our selection criterion is not in agreement with that in terms of Nash products, and an example is presented in which two strict Nash equilibria are simultaneously globally accessible when the friction is sufficiently small. Second, a class of games with invariant diagonal are proposed and shown to generically admit an absorbing and globally accessible equilibrium for small frictions.

We show that in all (whether generic or nongeneric) binary-action supermodular games, an extreme action profile is robust to incomplete information if and only if it is a monotone potential maximizer. The equivalence does not hold for nonextreme action profiles.