Projects, working papers, and slides:
Information Design for Rationalizable Outcomes (with O. Gossner) (updated draft coming very soon). Slides
We study (interim correlated) rationalizability in games with incomplete information. For each given game, we show that a simple and finitely parameterized class of information structures is sufficient to generate every outcome distribution induced by general common prior information structures. In these information structures players receive two kinds of signals: One of finitely many recommendations of play and a one-dimensional common state with additive, idiosyncratic noise. Using this result, we characterize the set of rationalizable distributions as a convex polyhedron.
A Strategic Topology on Information Structures (with Stephen Morris, Dirk Bergemann)
Two Information Structures are said to be close if, with high probability, there is approximate common knowledge that interim beliefs are close under the two information structures. We define an “almost common knowledge topology” reflecting this notion of closeness. We show that it is the coarsest topology generating continuity of equilibrium outcomes.
Global Game Selection in High Dimensions
We consider environments where agents make strategic investments in possibly many assets but have vanishing uncertainty about a high-dimensional fundamental of the economy. We show that if agents’ investment choices are related by some positive definite transformations, then any small uncertainty selects a unique equilibrium via unraveling.
Robust Information Aggregation. Slides
Consider an investment problem with strategic complementarities and incomplete information about returns. This paper shows that investors aggregate their private information in equilibrium by trading a token and observing its market price over multiple rounds before making an investment decision. This result is robust to the information environment. The paper gives an explicit trading protocol that robustly implements information aggregation and establishes properties of all such trading equilibria: Agents encode their private information in terms of a finite algebraic basis that spans the set of equilibrium token prices. Finally, the paper discusses the general implications of this result for privacy and the implementation of robust information aggregation.
Strategic Type Spaces (with O. Gossner). Slides, Recording
For a fixed finite game with incomplete information and solution concept, we define strategic type spaces (STS) as representations of players’ strategically relevant information. We construct the set of all hierarchies of best replies given by best replies to beliefs on other players’ best replies and show that they form a universal STS that is minimal among all STS. Unlike beliefs-hierarchies, we show that best-reply hierarchies are generated as the orbit of an operator on a finite space.
Policy and Applied Economics
- Schwellnus, C., Geva A., Pak M. and Veiel R. (2019), “Gig economy platforms: Boon or Bane?”, OECD Economics Department Working Papers, No. 1550, OECD Publishing, Paris, https://doi.org/10.1787/fdb0570b-en.