The old saying goes “而或长烟一空，皓月千里，浮光跃金，静影沉璧” (GPT translates) The vast mist disperses, unveiling a radiant moon that spans the heavens. Golden ripples dance upon the lake, while the still reflections sink like jade into the depths. A serene dusk lingers, cradling both the boundless beauty of nature and the quiet mind. Jan. 5, 2025. Hangzhou, West Lake. Jan. 5, 2025. Hangzhou, West Lake. Jan. 5, 2025. Hangzhou, West Lake.

The paper Test-Optimal Admissions by Dessein, Alex Frankel, and Navin Kartik has lingered on my desktop—and the Procrastination Bulletin—for over a year now. It’s time to give it the attention it deserves. ABSTRACT (from the authors) | Many U.S. colleges now use test-optional admissions. A frequent claim is that by not seeing standardized test scores, a college can admit a student body it prefers, say with more diversity. But how can observing less information improve decisions?...

The final thesis topics for the 2024 Fall E-Commerce course were quite intriguing (see it archived here). As market design requires detail and I found these logistic anecdotes—of characterizing different categories of product flows quite interesting and important. One of the most important operational considerations in e-commerce is how products flow. We can distinguish several logistics models based on the time it takes from when a customer pays for a product to the moment it arrives at their doorstep....

As I’m rushing through my final week, let me share about the E-commerce course I took this semester—our instructor commissioned two optional topics for its final thesis. Thinking about them is some fun exercise: Analyze the difference between e-commerce and traditional commerce in terms of product flow mechanisms—discuss your understanding of e-commerce risk management specific measures. How to solve problems when (i) platforms abuse the use of big data technology, for example, to conduct price discrimination; and (ii) platforms abuse their market power to limit seller’s multi-homing behavior and force exclusive commitment....

Here’s a gift to all for 2025’s beginning. It’s going to be a fun year. Will be to arrive where we started, and know the place for the first time. What we call the beginning is often the end. And to make an end is to make a beginning. The end is where to start from. — T.S. Eliot, Little Gidding.

Snippet from the press conference of National Health Commission of China, Dec. 25, 2024 (full transcript in Chinese available here). The reporter inquired the credibility of data related to mental psychology circulating on the Internet. (Xie Bin, Party Secretary of Shanghai Mental Health Centre) [There has been] rumours that the prevalence of depression among teenagers has reached 15%-20%. According to the results of epidemiological surveys by authoritative institutions, in fact, the prevalence of depression among adolescents in China is only about 2%....

My home university has a course that teaches intermediate-level Excel operations, made mandatory to all undergrads. On paper it looks great: you learn how to import and summarize data, create dynamic charts, and solve simple models for things like inventory or investment management. The course has a strong reputation, and many alumni speak highly of it. source: xkcd comics But here’s my take: for computer science major waste 64 hours of precious course load to teach skill that is key to non-promotable work which is going to be replaced by AI very soon....

A serie of works about incentives for early arrival: Ge, Yaoxin, et al. “Incentives for Early Arrival in Cooperative Games.” Proceedings of the 23rd International Conference on Autonomous Agents and Multiagent Systems. 2024. Zhang, Junyu, et al. “Incentives for Early Arrival in Cost Sharing.” Proceedings of the 24rd International Conference on Autonomous Agents and Multiagent Systems. 2025. The gem is because the problem is taken online. I’m surprised that algorithmic game theorists took the problem first before economists....

The most performed ballet is Nutcracker. Dance of the Sugar Plum Fairy gets 41M views on YouTube (here). Of course, Swan Lake is more famous. But Swan Lake requires excessive technique and giant production of a medium-large ballet company, whereas for Nutcracker, almost any area of US or Europe will have one, two, or four different productions of The Nutcracker at Christmastime—and Shanghai as well. Here are some pictures I took....

It’s that time of year again—graduate-entrance exams have just wrapped up, and for many people around me it’s a moment of reflection (or panic) as they contemplate what comes next. Amidst the usual stress and sleepless nights, another topic has quietly stirred debates among the community of exam-takers: the rise of so-called IQ-booster pills. Yes I’m talking about Methylphenidate—aka Ritalin. Real Quick Fact Check: ADHD, Ritalin, and Neurotransmitters For those unfamiliar, Ritalin is a prescription-only medication primarily used to treat ADHD (Attention Deficit Hyperactivity Disorder)....