Byeong-hyeon Jeong


Working Papers

Abstract: We study the impact of school choice on segregation. It shows that the popular school choice mechanisms lead to substantially different school and residential segregation, an important and overlooked aspect of choosing among school choice mechanisms. We show that open enrollment policy in public school choice program can decrease diversity of individual schools and increase segregation depending on which student allocation mechanism is used. Without open enrollment, we study the model of location choice and show that segregation is mainly associated with income. In comparing mechanisms, we show that Boston mechanism fosters segregation more than the deferred acceptance. If income and other characteristics are affiliated, the difference between BM and DA becomes more drastic. With open enrollment, another form of segregation can occur. We compare different student allocation mechanisms under open enrollment and show that Boston mechanism can worsen segregation and decrease diversity of individual schools. The deferred acceptance with multi tie breaking creates maximally diverse schools.

Abstract: This paper studies one-to-one matching environment without transfer in the presence of incomplete information on one-side. The existing notions of stability under incomplete information are studied and two alternatives are proposed. Weak Bayesian stability requires that the beliefs of the agents are derived from a common prior via Bayes’ rule and are internally consistent with the presumption that the given matching is stable. Strong Bayesian stability refines weak Bayesian stability by requiring the beliefs of agents are also externally consistent in the sense that the beliefs are narrowed down only when there is a valid reason.

We consider conventional auctions when the seller can design bid spaces. Any symmetric equilibrium in a second price auction with bid spaces can be replicated with an equilibrium in a first price auction with bid spaces, but the converse doesn't hold. First price auctions with designed bid spaces revenue dominates second price auction with designed bid spaces, and well-designed first price auction is an optimal selling mechanism.

Abstract: We study mechanisms for robust allocation of a divisible public good among n agents with quasi-linear utilities, when the budget is exactly balanced. Under several additional assumptions, we prove that such mechanism is equivalent to a distribution over simple posted prices. A robustly optimal mechanism minimizes expected welfare loss among robust divisible ones. For any prior belief, we show that a simple posted prices is robustly optimal. This justifies a restriction to binary allocations commonly found in the mechanism design literature. Robustness comes at a high cost. For certain beliefs, we show that the expected welfare loss of an optimal posted price is as big as 1/2 of the expected welfare in the corresponding optimal Bayesian mechanism, independently of the size of the economy. This bound is tight for the special case of two agents.