Some sidenotes from price theory iii: Definitions For distributions (pdf) $f_1(\cdot), f_2(\cdot)$: Monotone Likelihood Ratio (MLR): let ratio $$ \phi(l) = \frac{f_1(l)}{f_2(l)}. $$ $f_1$ dominate $f_2$ (in MLR sense) iff. $\phi(l)$ is weakly increasing in $l$. Intuition: Pointwise relative density shifts up Hazard Rate Dominance (HRD): define the hazard rate (aka conditional failure rate): $$ h_{f_i}(l) = \frac{f_i(l)}{1 - F_i(l)} \quad i =1, 2. $$ $f_1$ dominate $f_2$ (in HRD sense) iff. $h_{f_1}(l)\le h_{f_2}(l), \forall l$. ...

It’s very intellectually stimulating to read Professor Stiglitz’s book, or if you’re as lazy as me, playing his YouTube archive recording of the book launch at UChicago. Professor Stiglitz’s most provocative point is almost saying the invisible hand doesn’t exist. Making this claim at the University of Chicago is dangerous… But basically, Kenneth Arrow (also a Chicago veteran) proved the conditions under which Adam Smith’s invisible hand claim holds — and showed how narrow those conditions are. Stiglitz’s argument is that then economists cherry-picked Arrow’s conclusion and ignored his caveats. They took a theorem with heavy asterisks and preached it as gospel. ...

I found a very inspiring video from the digital marketing industry that has economic insights: The video is long. Here’s what I found interesting: The core claim is, micro-influencers (10K–100K followers) deliver positive ROI ~36% of the time. Mega-influencers lose money in 59% of campaigns. Follower count is a poor predictor of returns. Why: Micro influncer is “community based distribution”, like not ads but genuine communication. Engagement is ~4x higher than branded accounts, and you can activate ~100 micro-creators for the cost of one celebrity. ...

Jakub Hrůša and presents Songs of Love and Farewell Death with the CSO — look at the thoughtful program: Janáček Overture to From the House of the Dead Rachmaninov The Isle of the Dead R. Strauss Four Last Songs, with soprano Corinne Winters Wagner Prelude and Liebestod from Tristan and Isolde (Orchestral version) It is a very spiritual experience. My friend says “I feel like I’m floating and entering an ethereal state, and the music just ends there”. ...

Yu Long is our most famous conductor, famous for lot of things: leader of Chinese classical scene, a good Brahms interpreter, and his most popular meme: China’s classical music scene is growing — while young ppl flood into the concert hall to enjoy the music, we also want to show off our music taste by posting “repos” on Social Media (📕), sometimes a little bit overly mean and picky. ...

AlphaFold2, released by DeepMind in 2020 and made freely available in July 2021, uses deep learning + DNA sequence alignment to predict a protein’s 3D structure at near-experimental accuracy, and generalizes well out-of-sample. This solves a 50-year-old open problem in structural biology and won 2024 Nobel Prize in Chemistry. MOREOVER, DeepMind ran AlphaFold2 on essentially every known protein and release a free database lookup. Though note its key limitations are: AlphaFold predicts a single static “default” conformation and misses the flexibility, ligand-bound states, and allosteric changes that matter most for drug design; ~10% of high-confidence residues are still meaningfully misplaced; and it is pattern recognition over evolutionary data, not a physics-based simulation. ...

Professor Richard Holden from UNSW Sydney came to our theory seminar to give a talk about his paper [“Getting the Picture”](https://economics.uchicago.edu/sites/default/files/users/user337/Holden Getting the Picture.pdf). The paper’s idea of modeling an individual who has limited working memory originates from cognitive science. But gives a strong computer science flavor. Here’s my notes from student coffee seminar. We think there are certain computer science work can be done for it: Model Definitions Input: $P \in \mathcal P \subseteq \Omega^{MN}$ ...

Professor Ozlem Ergun (Northeastern University) gave a talk at Booth’s OM seminar titled Enhancing the Effectiveness of Humanitarian Services Through Data-Driven Optimization. I found a similar YouTube recording online: The slide at 7:47 (shown below) gives a useful overview of the global food aid supply chain: All rights belong to Professor Ergun and her coauthor — I don’t own copyright. Though I like this picture very much. ...

听风听雨过清明 (Hearing the wind and rain during Qingming) 吴文英《风入松·听风听雨过清明》 It’s Qingming today (and Easter!). Qingming aka tomb sweeping day is a traditional holiday that honors our family ancestors that passed away. As it evolves, it has also gradually becoming a mark for prime spring — an honorary of the season’s booming spirits. Somewhat interestingly, ballet companies China would program Giselle for Qingming festival every year. Excellent timing… This is just a tiny though quite modern and interesting example to see how culture learn from each other. ...

My pianist Isaac Cohen and I recently performed the Prokofiev Flute Sonata at the First Unitarian Church of Chicago. The church has a generous, echoing acoustic. It is beautiful to listen to, though not always the easiest space in which to play—particularly for the flute. To project into the space you must give the instrument a great deal of breath. Prokofiev was famously dry, terse, allergic to sentimentality. He probably just wrote this sonata because the flute is an underrated instrument and he wanted to do something about that — thus a piece that is so technically demanding and classic Prokofiev — precussive piano lines, mysteriously beautiful chord progressions, and crazy scales up and down as if flutes don't need to breathe. I think I played reasonably well. Yet after the performance I felt terrible. In my memory the piece seemed full of mistakes—slips, cracks, moments where the line did not quite bloom the way I imagined it. ...