There's this pet peeve I have where people sometimes ask things like what kind of strategies they should use for, say, collinearity problems in geometry. Like, I know there are valid answers like Menelaus or something. But the reason it bugs me is because "the problem says to prove collinearity" is about as superficial as… Continue reading Imperative statements in geometry don’t matter
Author: Evan Chen (陳誼廷)
Evan is a math olympiad coach who completed his number theory PhD at MIT.
A proof of Poncelet Porism with two circles
Brian Lawrence showed me the following conceptual proof of Poncelet porism in the case of two circles, which I thought was neat and wanted to sketch here. (This is only a sketch, since I'm not really defining the integration.) Let $latex {P}&fg=000000$ be a point on the outer circle, and let $latex {Q}&fg=000000$ be the… Continue reading A proof of Poncelet Porism with two circles
The story of the AutoCarrot
1. Glazed carrots Okay. Imagine you’re, like, trying to make glazed carrots or something. Maybe a really simplified recipe looks something like: Cut your carrots into suitably sized pieces with a knife. Use a measuring spoon to get the right amount of oil, sugar, salt, etc. Throw the carrots and other ingredients into a frying… Continue reading The story of the AutoCarrot
OTIS X applications are open
The tenth year of OTIS is now accepting applications. Due August 1, 2024 for regular deadline and April 30, 2025 for late applications. https://web.evanchen.cc/otis.html#apply The application and syllabus are pretty much going to be the same as in previous years; here are some of the (mostly small) changes: I deleted the question that used to… Continue reading OTIS X applications are open
Infinitely many stages of grief
Where do all the smart, curious, earnest kids go these days? One of my friends asked me this recently, and I wasn’t sure what to say. In the last ten years, something has changed. If I had to summarize my concerns in one sentence, I would say this: kids these days no longer feel they’re… Continue reading Infinitely many stages of grief
(EC)⁵: College Essay Consulting
Calling all high school juniors! We’re proud to announce a new educational service to accompany last year’s ⛵IS: Evan’s Chen’s Elite Cutting-Edge College Essay Consulting & Editing Center! Abbreviated (EC)⁵. Why trust Evan? Evan Chen is one of the leading names in admissions to elite American colleges. Students that Evan has mentored have gone on… Continue reading (EC)⁵: College Essay Consulting
Brianchon is fair game
About five years ago I wrote a blog post warning that I thought it was a bad idea to design math olympiads to be completely untrainable, because I think math olympiads should be about talent development rather than just talent identification, yada yada yada. So now I want to say the other direction: I also… Continue reading Brianchon is fair game
NP-hard advice questions
Sometimes I get asked broad advice questions on solving problems, for example questions like: How do I know when to switch or prioritize approaches I come up with? How do I know which points or lines to add in geometry problems? How can I tell if I’m making progress on a problem? How can I… Continue reading NP-hard advice questions
Against exploitable rubrics
Editorial note: this post was mostly written in February 2023. Any resemblance to contests after that date is therefore coincidental. Background A long time ago, rubrics for the IMO and USAMO were fairly strict. Out of seven, the overall meta-rubric looks like: 7: Problem solved 6: Tiny slip (and contestant could repair) 5: Small gap… Continue reading Against exploitable rubrics
January newsflash
Here’s a mix of several publicity-related things I’d like to broadcast. AlphaGeometry A lot of you have already heard the buzz about the AlphaGeometry news and Nature paper. (I’ve known about this paper for a while now, so I’m glad I can finally talk about it!) I managed to snag a cameo in the DeepMind… Continue reading January newsflash
Power Overwhelming 