Steve Yeh
About Me
I am currently a 5th year PhD student in the Department of Economics at Columbia University.
My research interests include networks and game theory. I am advised by Prof. Evan Sadler.
I graduated Summa Cum Laude in Economics and Magna Cum Laude in Mathematics (Concentration in Pure Math) with Minors in Computer Science and Law & Society from Cornell University in May 2021.
My CV is linked here.
Working Papers
Plausible Pairwise Stability
Abstract
I propose a stability concept for network formation under incomplete information. A network is plausibly pairwise stable if players’ beliefs are consistent with common knowledge of network stability. I provide a general condition under which plausibly pairwise stable networks exhibit clustering. In a simple model of vertical differentiation, I characterize minimal plausibly pairwise stable networks. I show that incomplete information can stabilize segregated and sparse networks that are unstable under complete information. I discuss how incomplete information resolves the tension between stability and efficiency in the presence of negative linking externalities.Presented at: 36th Stony Brook International Conference on Game Theory, 2026 North American Summer Meeting of the Econometric Society.
A Shocking Reversal: Flipping Complements and Substitutes in Network Games (with E. Sadler)
Accepted at EC ‘26.
Abstract
In conventional network games, each player chooses one action that impacts all of her neighbors. We study players that select neighbor-specific efforts and face a convex total effort cost. Our main result highlights a striking reversal in comparative statics: When bilateral efforts are strategic complements (substitutes), shocks propagate through the network in a pattern befitting strategic substitutes (complements) in standard network games. This reversal, together with other fundamental changes in player behavior, suggests that retaining the single effort assumption when it is not appropriate may lead to poor policy recommendations.Presented at: 11th Annual Conference on Network Science and Economics, EC ‘26 (Upcoming).
Optimal Project Task Assignments
Abstract
A principal assigns agents to tasks in a multi-task project. Agents tend to shirk at their tasks and rely on others’ efforts because effort on one task substitutes for effort on similar tasks. Assigning the same agent to more tasks mitigates free-riding, but convex effort costs prevent him from completing all of his tasks. For a class of projects, an optimal task assignment assigns each agent to a module comprising a task central to the project and all locally related tasks. For general projects, modular task assignments are approximately optimal with a performance guarantee that depends on a project's task structure.Presented at: 35th Stony Brook International Conference on Game Theory, Northwestern-Kellogg Summer School in Economic Theory.
Works-in-Progress
A Network Theory of Project Management.
Refereeing
Program Committee for EC’26, Journal of Economic Theory.