- Forbidden Transactions and Black Markets: (with Chenlin Gu and Alvin E. Roth)
**Forthcoming, Mathematics of Operations Research.**Repugnant transactions are sometimes banned, but legal bans sometimes give rise to active black markets that are difficult if not impossible to extinguish. We explore a model in which the probability of extinguishing a black market depends on the extent to which its transactions are regarded as repugnant, as measured by the proportion of the population that disapproves of them, and the intensity of that repugnance, as measured by willingness to punish. Sufficiently repugnant markets can be extinguished with even mild punishments, while others are insufficiently repugnant for this, and become exponentially more difficult to extinguish the larger they become.

- Dynamic Matching with Teams:
**Forthcoming, Operations Research Letters.**This paper studies a dynamic matching model in which a matchmaker creates team based game sessions for sequentially arriving players and seeks a balance between fairness and waiting times. We derive a closed-form optimal matching policy and show that as the team size grows and the market becomes more balanced, greedy policies become less appealing.

- Wu, Qingyun. "Entering Classes in the College Admissions Model."
**Games and Economic Behavior**124 (2020): 579-587.This paper reveals a characteristic of stable matchings in the college admissions problem and provides structural insights and a unified treatment for several results in this model, including the famous "Rural Hospital Theorem". We also show that the worst student determines the whole entering class.

- Wu, Qingyun and Alvin E. Roth. "The Lattice of Envy-free Matchings."
**Games and Economic Behavior**109 (2018): 201-211.This paper studies a many-to-one matching model, and shows that the set of envy-free matchings is a lattice. A Tarski operator on this lattice that can be interpreted as modeling vacancy chains, has the set of stable matchings as its fixed points.

- Mathematics Behind Go Endgames (2014):
This was my undergraduate mathematics honor thesis, advised by Dr Florian Block. It studies Go endgames with tools in combinatorial game theory.

- A Study of 2Xn and 3Xn Domineering (2010):
My math 191 project with Michael Landry, advised by Dr Daniel Cristofaro-Gardiner. We solve 2xn (except 2x31) and 3xn Domineering games by pure combinatorial arguments. The problem was first solved in the 1980s by Berlekamp. But he used advanced results from temperature theory, while we only use simple primitive arguments (a little bit tedious of course).

- A Combinatorial Game Theoretic Analysis of Chess Endgames (2010):
Another math 191 project with Michael Landry and Frank Yu, again advised by Dr Daniel Cristofaro-Gardiner. It is a note on how to do basic analysis on chess endgames with combinatorial game theory.

- Constructing Local Inequalities Using Function Concavity (2009), Bulletin of Mathematics, 10, 30-31
:
My first ever "paper" published in China, back to the days when I was a high school student. It introduces a method of constructing local inequalities based on function concavity, which is similar to the supporting hyperplanes in the proof of Jensen's inequality.

- An Important Characteristic of Equilateral Triangles (2009), Company in Mathematics, 20, 59-60
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Another article I wrote when I was in high school. It describes a characteristic of equilateral triangles in the form of complex numbers. When applied properly, it can solve difficult geometry problems with ease.