For me the biggest difference between undergraduate math and PhD life has been something I’ve never seen anyone else talk about: it’s the feeling like I could no longer see the ground.

To explain what this means, imagine that mathematics is this wide tower, where you start with certain axioms as a foundation, and then you build upwards on it. At first learning math felt like slowly climbing up this tower. When I reached a landmark, it felt like I was on the balcony of the 30th or 50th or 100th floor, enjoying the view, with an appreciation of the floors I had ascended to get here.

In theory, proofs in math can be formalized as a long sequence of logical steps from the axioms that could be computer-verified. This turns out to way too cumbersome to actually do in practice given the current state of technology (though …

The Carina Initiatives (https://carina.fund) is a friend of the math education community which has supported organizations like Art of Problem Solving, BEAM, Athemath, and others. They’re starting a math talent search organization in the United States and are looking to hire a full-time leader (salary $200K-$250K).

Passing this along in case anyone in this space might be interested in applying or knows someone who might be. The link to apply is:

https://carina-initiatives-inc.breezy.hr/p/4ff029962ddc-executive-in-residence-math-talent-search

Last weekend in StarCraft, the world championship at IEM Katowice 2023 saw a so-good-it-must-be-scripted Cinderella story, where Oliveira won the world championship in a totally unexpected way. It was a whole roller-coaster of upset after upset from Oliveira, and up until the grand finals we were all still asking, “this can’t be, is this really happening?”.

Some context: StarCraft has one of the lowest upset rates of any competitive game out there, and Oliveira (formerly known as TIME) was ranked something like #21 coming in. Last November at DreamHack Atlanta (which I was at!), he didn’t win a single map. And just a month before IEM 2023, Blizzard had shut down its Chinese servers. But he’d been practicing 12 to 15 hours a day lately, and it showed.

The final winner interview was so emotional not only did Oliveira start crying, the host also started crying …

I’m happy to thank 日本評論社 and their team (Fuma Hirayama, Yuki Kumagae, Taiyo Kodama, Ayato Shukuta, among others) for making the Japanese translation a reality. As well as tripling the length of the errata PDF :)

This marks the second translation of the EGMO textbook (a Chinese translation was published a while ago as well by Harbin Institute of Technology). Both linked below:

• Japanese translation at nippyo.co.jp and amazon.co.jp. ISBN-10: 4535789789 / ISBN-13: 978-4535789784.
• Chinese translation at abebooks and amazon. ISBN-10: 7560395880 / ISBN-13: 978-7560395883.

This is a retro-post for the Mystery Hunt 2023, for which I played a somewhat minor role on the organizing team (teammate). You can play at interestingthings.museum.

There is an ongoing list of write-ups about the hunt being kept at puzzles.wiki, and you may also be interested in the reddit AMA from teammate.

Puzzle shoutout list

Favorite puzzles

The obligatory list.

• Hall of Innovation round
• You’re Telling Me (Atrium)
• Showcase (Atrium)
• Lost to Time (Basement)
• 5D Barred Diagramless with Multiverse Time Travel (Böotes)
• Subterranean Secrets (Basement), but this puzzle required being on-campus

Puzzles I am an author on

• Much Ado About Nothing (Atrium)
• Diagramless (Office), with Lumia Neyo.
• Circuit (Basement), with Jacqui Fashimpaur.
• Zambonis (Office), with Catherine Wu, Nicholai Dimov, and Steven Silverman
• 4D Geo (Wyrm), with Austin Lei, Moor Xu, and Nathan Wong
• Flooded Caves (Wyrm), with Alex Gotsis and Cameron Montag

Also a …

There’s a common error I keep seeing on OTIS applications, so I’m going to document the error here in the hopes that I can preemptively dispel it. To illustrate it more clearly, here is a problem I made up for which the bogus solution also gets the wrong numerical answer:

Problem: Suppose $a^2+b^2+c^2=1$ for positive real numbers $a$, $b$, $c$. Find the minimum possible value of $S = a^2b + b^2c + c^2a$.

The wrong solution I keep seeing goes like so:

Nonsense solution: By AM-GM, the minimum value of $S$ is $S\ge 3\text{exception 25:}$

A while ago someone asked me how COVID had affected the students I worked with. I replied that, on average, the pandemic had tripled my students’ productivity.

And I’m gonna brag about it like the proud teacher I am.

Couple Thanksgiving presents for y’all:

Errata List now on GitHub

The list of errata is now version controlled on GitHub: vEnhance/egmo-book-errata. So now you can actually see a changelog of the ocean of typos as they come in.

Shout-out to the crew working on the Japanese translation of the book for finding way more errors than I will ever care to admit (I didn’t count, but it’s probably in the 200-300 ballpark).

Automatically Generated EGMO Solutions Treasury (AGEST)

I took a snapshot my database entries for sourced problems in EGMO. It turns out that I have many written up already, so we now have something of a solutions manual for about half the problems or so. Since I like idiotic names, I dubbed it the Automatically Generated EGMO Solutions Treasury.

You can download it here: web.evanchen.cc/textbooks/AGEST.pdf

Some people have asked me why I anti-recommend JavaScript for beginners on my website FAQ. This post will try to give a few reasons why.

Some notes:

• I’m referring to base JS. I like TypeScript a lot for example (it’s high on my tier list of programming languages for beginners). And I know about eslint, but you asked me about recommendations for beginners, and I think beginners shouldn’t have to worry about setting up an IDE with strict linting until after they can write a for loop by themselves without screwing up.
• I have multi-file projects in mind. I don’t have a problem with using inline JavaScript for tiny 20-line snippets of code embedded in a webpage.
• I’m an amateur programmer. Professional programming is a different ball game.

Weak typing

I’m clumsy. I make many more mistakes than the average programmer. The other day …

don’t ask why it just came in my head

Quandary

So you have a fair coin that you found on the ground,
or at least that’s what everyone says.
But on each of N times that you’ve tossed it around,
you see every flip has been heads.

For which value of N should you start to suspect
that the coin isn’t actually fair?
For which values of N can you firmly declare
that the tails side is not even there?