Publications
Matching Mechanisms for Refugee Resettlement
Joint with Scott Duke Kominers and Alexander Teytelboym
American Economic Review, 113 (10): 2689-2717, October 2023
A former version circulated in 2016 under the title “Refugee Resettlement” and is available here
Presented at the 2016 NBER Market Design Working Group Meeting
Media coverage: Financial Times, Bloomberg, News Deeply
Application: Refugees.AI
Abstract: Current refugee resettlement processes account for neither the preferences of refugees nor the priorities of hosting communities. We introduce a new framework for matching with multidimensional knapsack constraints that captures the (possibly multidimensional) sizes of refugee families and the capacities of communities. We propose four refugee resettlement mechanisms and two solution concepts that can be used in refugee resettlement matching under various institutional and informational constraints. Our theoretical results and simulations using refugee resettlement data suggest that preference-based matching mechanisms can improve match efficiency, respect priorities of communities, and incentivize refugees to report where they would prefer to settle.
When Walras Meets Vickrey
Joint with Simon Loertscher and Claudio Mezzetti
Theoretical Economics, 17 (4): 1803-1845, November 2022
Abstract: We consider general asset market environments in which agents with quasilinear payoffs are endowed with objects and have demands for other agents’ objects. We show that if all agents have a maximum demand of one object and are endowed with at most one object, the VCG transfer of each agent is equal to the largest net Walrasian price of this agent. Consequently, the VCG deficit is equal to the sum of the largest net Walrasian prices over all agents. Generally, whenever Walrasian prices exist, the sum of the largest net Walrasian prices is a nonnegative lower bound for the deficit, implying that no dominant-strategy mechanism runs a budget surplus while respecting agents’ ex post individual rationality constraints.
Comparative Statics for Size-Dependent Discounts in Matching Markets
Joint with Scott Duke Kominers and Alexandru Nichifor
Journal of Mathematical Economics, 90: 127-131, October 2020
Abstract: We prove a natural comparative static for many-to-many matching markets in which agents’ choice functions exhibit size-dependent discounts: reducing the extent to which some agent discounts additional partners leads to improved outcomes for the agents on the other side of the market, and worsened outcomes for the agents on the same side of the market. Our argument draws upon recently developed methods bringing tools from choice theory into matching.
Essentially Stable Matchings
Joint with Peter Troyan and Andrew Kloosterman
Games and Economic Behavior, 120: 370-390, March 2020
Abstract: We propose a solution to the conflict between fairness and efficiency in one-sided matching markets. A matching is essentially stable if any priority-based claim initiates a chain of reassignments that results in the initial claimant losing the object. We show that an essentially stable and Pareto efficient matching always exists and that Kesten’s (2010) EADA mechanism always selects one while other common Pareto efficient mechanisms do not. Additionally, we show that there exists a student-pessimal essentially stable matching and that the Rural Hospital Theorem extends to essential stability. Finally, we analyze the incentive properties of essentially stable mechanisms.
Two-Sided Allocation Problems, Decomposability, and the Impossibility of Efficient Trade
Joint with Simon Loertscher, Leslie Marx, and Tom Wilkening
Journal of Economic Theory, 179: 416-454, January 2019
Abstract: Previous literature has shown that private information is a transaction cost that prevents efficient reallocation in two-sided setups with bilateral trade or homogeneous goods. We derive conditions under which the impossibility of efficient trade extends to rich environments in which buyers and sellers have multi-dimensional private types, accommodating many-to-many trades and heterogeneous objects. If agents can be decomposed into unit constituents, the allocation problem can be represented as an assignment game and impossibility obtains through a generalization of Shapley’s (1962) result that buyers and sellers are complements. We introduce a general family of payoff functions that ensures decomposability and thus impossibility.
Working Papers
Public Good Provision: The Lindahl-VCG Relationship NEW! (Dec 2023)
Abstract: We consider a public good environment in which the agents consuming the public good have quasilinear utility. We show that if the public good must be provided as a single, indivisible unit, then the VCG transfer paid by each agent is equal to the \emph{smallest Lindahl expenditure} of this agent, while the largest Lindahl revenue of the firm is equal to the VCG transfer received by the firm. If the public good can be provided in multiple units, then the smallest Lindhal price of an agent is an upper bound on the agent’s marginal VCG transfer for each unit on which the agent is pivotal, and the largest Lindahl revenue of the firm is a lower bound on the firm’s VCG transfer. Consequently, the difference between the largest Lindahl revenue of the firm and the sum of the smallest Lindahl expenditures of each agent is equal to the VCG deficit with a single unit and a lower bound on the VCG deficit with multiple units. Our results extend to the provision of public bads such as data usage by platforms that harms consumers.
Processing Reserves Simultaneously [10min talk] [25min talk] [60min talk]
Extended Abstract in the Proceedings of the 22nd ACM Conference on Economics and Computation (2021), pp.345-6
Best Job Market Paper Award, European Economic Association and UniCredit Foundation (2020)
Presented at the 2020 NBER Market Design Working Group Meeting
The job market version (October 2020) is available here and the first version (August 2020) is available here
Abstract: Policymakers frequently use reserve categories to combine competing objectives in allocating a scarce resource based on priority. For example, schools may prioritize students from underprivileged backgrounds for some of their seats while allocating the rest of them based solely on academic merit. The order in which different categories are processed has been shown to have an important yet subtle impact on allocative outcomes—and it has led to unintended consequences in practice. I introduce a new, more transparent way of processing reserves, which handles all categories simultaneously. I characterize my solution, showing that it satisfies basic desiderata and is category neutral: if an agent qualifies for n categories, she takes 1/n units from each of them. A practical advantage of this approach is that the relative importance of categories is entirely captured by their quotas.
Stability in Matching Markets with Sizes
A former version circulated in 2017 and is available here.
Abstract: Matching markets such as day care, student exchange, refugee resettlement, and couples problems involve agents of different sizes, that is agents who require different amounts of capacity. I study a matching market between agents and objects where the size of an agent is either one or two. Contrary to canonical models, the set of stable matchings may be empty. I identify a trade-off for existence: it is always possible to either bound the instability to a certain number of units per object or to eliminate waste but the existence of a matching that does both is not guaranteed. I develop two fairness criteria that lie on either side of this trade-off: unit-stability bounds the instability and size-stability eliminates waste. I show that size-stability is more desirable than unit-stability from a welfare point of view.