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Jordan Ellenberg

@jsellenberg.bsky.social

Mathematician, writer, Orioles fan, Wisconsinite, cargo shorts dad

3,150 Followers  |  156 Following  |  419 Posts  |  Joined: 27.06.2023
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Posts by Jordan Ellenberg (@jsellenberg.bsky.social)

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Networking and granfallooning It has come to my attention that students at prestigious universities are referring to the practice of cold-emailing alums of their school and asking for Zoom calls to discuss possible summer inter…

quomodocumque.wordpress.com/2026/02/27/n...

28.02.2026 02:23 — 👍 3    🔁 0    💬 0    📌 0
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In which I rescue Harvard’s grading system The Harvard faculty is proposing to hard-cap A’s at 20% per course, leading to an undergraduate crashout the good old Yard has not seen the likes of since,the dining hall discontinued the Chi…

quomodocumque.wordpress.com/2026/02/25/m...

26.02.2026 02:17 — 👍 7    🔁 2    💬 0    📌 0
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Waiting for Godot (Gen-X rewrite) Here’s a good use case for LLMs — they are quite good at recovering the text from files you saved on a Macintosh word processor in the early 90s and have been transporting from computer…

quomodocumque.wordpress.com/2026/02/18/w...

19.02.2026 02:17 — 👍 2    🔁 1    💬 1    📌 0
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Now pitching, Cadeler Wellvich Barring any last-minute moves, and despite being linked to just about every big-name pitcher on the free-agent market, the Orioles will go into 2026 as they left 2025, without a clear #1 starter. D…

quomodocumque.wordpress.com/2026/02/06/n...

07.02.2026 03:41 — 👍 1    🔁 0    💬 0    📌 0
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What’s the entropy of a random integer? Surely people have thought about this but I couldn’t find anything on a short search. The question: let n be a random integer, say in [N,2N]. It factors as the product of p_i^a_i. So you can …

quomodocumque.wordpress.com/2026/02/03/w...

04.02.2026 13:30 — 👍 3    🔁 0    💬 1    📌 0
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Dick Gross Dick Gross died last month. Much has already been written, and during his lifetime too, about his immense contributions to modern number theory. So I won’t try to cover that here — don&…

quomodocumque.wordpress.com/2026/01/18/d...

20.01.2026 00:48 — 👍 8    🔁 1    💬 0    📌 0
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It’s a good old-fashioned Wisconsin booger-freezer out there! One of my favorite weather sayings. And I ran into a neighbor on my way home from the errand I was running so I got to say it in person, always a treat. 3 degrees Fahrenheit, sunny and windy in Mad…

quomodocumque.wordpress.com/2026/01/19/i...

19.01.2026 22:43 — 👍 2    🔁 0    💬 0    📌 0
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If one is not to make a mess of life “One must be fond of people and trust them if one is not to make a mess of life, and it is therefore essential that they should not let one down.” From E.M. Forster, “What I Belie…

quomodocumque.wordpress.com/2026/01/17/i...

18.01.2026 15:13 — 👍 2    🔁 0    💬 0    📌 1
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Bruhat intervals that are large hypercubes New paper up on the arXiv! With Nicolas Libedinsky, David Plaza, José Simental, Geordie Williamson, and (unofficially) Adam Zsolt Wagner. A bunch of algebraic combinatorists! And this is a combinat…

quomodocumque.wordpress.com/2026/01/12/b...

12.01.2026 22:03 — 👍 4    🔁 2    💬 0    📌 0
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Dyadiku I made a game. It’s like Sudoku but dyadic. It’s called Dyadiku. Try it! I’m very interested to see whether people find it playable and fun — in particular, does it admit a …

quomodocumque.wordpress.com/2026/01/05/d...

07.01.2026 00:08 — 👍 4    🔁 0    💬 0    📌 0
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Reaching the masses (not a Marxist post) Six popular math authors, including me, did a round-table interview for the Notices of the American Mathematical Society about talking about math to the non-academic public, or, as the Notices call…

quomodocumque.wordpress.com/2026/01/05/r...

05.01.2026 21:16 — 👍 3    🔁 0    💬 0    📌 1
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Self-portrait with about one quarter of Richard Serra’s sculpture Equal Visit the post for more.

quomodocumque.wordpress.com/2025/12/23/s...

24.12.2025 16:56 — 👍 6    🔁 0    💬 0    📌 0
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The American people have just one fixed idea “The American people have just one fixed idea and, since that dominant thought is money, it follows that their spirit has a certain uniform and unpleasant dryness… prodigality is an unf…

quomodocumque.wordpress.com/2025/12/19/t...

20.12.2025 02:23 — 👍 5    🔁 2    💬 0    📌 0
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How I know zombies aren’t real This piece of marketing doggerel from McDonald’s, concerning their Xmas-special Grinch meal, is the most foully defiling attempt to imitate Dr. Seuss’s verse I’ve ever encountered…

quomodocumque.wordpress.com/2025/12/12/h...

13.12.2025 20:19 — 👍 3    🔁 0    💬 0    📌 0
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Another example: sets of arcs and loops with bounded intersection Yet another example of the kind of problem that falls under the sphere packing / cap set / Turan umbrella I blogged about last week. Let G be SL_2(Z) and H be upper triangular matrices. Then G/H is…

quomodocumque.wordpress.com/2025/12/03/a...

05.12.2025 00:58 — 👍 2    🔁 0    💬 0    📌 0
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Random Americans, ethnic stereotypes, and large language models I have been reading about the tendency of poll respondents to overestimate the size of small population subgroups (e.g. if you ask Americans what proportion of Americans are Jews, they’ll say…

quomodocumque.wordpress.com/2025/11/30/r...

30.11.2025 23:55 — 👍 4    🔁 1    💬 1    📌 0
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“Not Vegan” I saw a guy today wearing a hoodie that said “Not Vegan.” I’m not vegan either, not even close, but come on. This is like wearing a “Yankees Suck” shirt. I hate the Ya…

quomodocumque.wordpress.com/2025/11/27/n...

28.11.2025 16:07 — 👍 5    🔁 0    💬 2    📌 0
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Mathgiving Happy Thanksgiving to all my American readers, and hey, everyone else too — gratitude is global. In the US, this is the start of the season where people customarily think about their charitab…

quomodocumque.wordpress.com/2025/11/27/m...

28.11.2025 00:02 — 👍 6    🔁 1    💬 0    📌 0
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Sphere packing, cap set, and the Turán problem are all the same thing OK, they are not really the same thing. But I got you reading, right? Here’s the sense in which they’re all the same thing. Let G be a group and H < G a subgroup. Let m > 1 be an …

quomodocumque.wordpress.com/2025/11/24/s...

25.11.2025 17:57 — 👍 6    🔁 0    💬 0    📌 0
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Let us now praise United Airlines I did manage to get home last night from Providence, despite widespread cancellations and delays caused by the government shutdown de-staffing air traffic control. United was speedy, flexible, and …

quomodocumque.wordpress.com/2025/11/08/l...

08.11.2025 22:16 — 👍 3    🔁 0    💬 0    📌 0
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I reviewed a book about the math foundations crisis for the New York Times I thought the book had some interesting virtues but was also quite badly overwritten, and very confusing in its treatment of the mathematics. Here’s my review. For length reasons I wasn’…

quomodocumque.wordpress.com/2025/11/07/i...

08.11.2025 20:17 — 👍 6    🔁 0    💬 1    📌 0
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Risk Modeling and Management for Natural Disasters Innovation by the Numbers | National Academies Learn more from the National Academies of Sciences, Engineering, and Medicine

I'm moderating an online discussion for the National Academies today, 3pm eastern, on math, risk management, and natural disasters!

www.nationalacademies.org/event/45862_...

14.10.2025 14:47 — 👍 7    🔁 0    💬 0    📌 0
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MacArthur Fellows: Wisconsin and Williams The 2025 MacArthur Fellows have been announced, and I’m very pleased that two of the 22 awardees are my UW-Madision colleagues: congratulations to Ángel F. Adames Corraliza from atmospheric a…

quomodocumque.wordpress.com/2025/10/08/m...

10.10.2025 00:00 — 👍 5    🔁 0    💬 0    📌 0
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Claudia Prieto, “Tus Ojos” Claudia Prieto is a Venezuelan singer-songwriter about whom I know next to nothing except that she recorded this gorgeous song, “Tus Ojos,” in 2018. By the way, I found out about this s…

quomodocumque.wordpress.com/2025/09/30/c...

05.10.2025 14:33 — 👍 3    🔁 1    💬 0    📌 0
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Taylor Swift and Stephanie Burt, or: Life of a Harvard English Professor It’s Taylor Swift album day! We listened to it last night at 11pm central when it went live. Snap reaction from AB, for whom 1989 is apex Swift and the last two albums have been too moody and…

quomodocumque.wordpress.com/2025/10/03/t...

04.10.2025 01:35 — 👍 0    🔁 0    💬 0    📌 0
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I gave a talk about machine learning and math I, too, spoke at the CMSA Big Data conference where this cool math bio talk took place. If you’ve seen me give a talk about math and machine learning lately, you’ve seen some of the sli…
04.10.2025 01:23 — 👍 8    🔁 1    💬 1    📌 0
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Global epistasis emerges from a generic model of a complex trait (or: random walks on a hypercube with reweighting) I still don’t really know what global epistasis is, but I really enjoyed Gautam Reddy’s talk about this paper at the CMSA Big Data conference two weeks ago. I’ll describe it, in c…
03.10.2025 01:17 — 👍 5    🔁 0    💬 0    📌 0
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Mura Yakerson interviewed me And we talked about math, writing, standup comedy, the art of interviewing (meta!) Mura’s whole channel is great. Bisi Agboola! Helene Esnault! Steve Strogatz! Mura’s mom! Check it out.
30.09.2025 23:08 — 👍 8    🔁 1    💬 0    📌 0
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Klartag improves the sphere-packing constant Hey! It escaped my notice until this week that Boaz Klartag has recently shown the existence of lattice sphere packings in dimension d of density at least c d^2 2^-d. This lower bound was stuck at …
30.09.2025 00:52 — 👍 9    🔁 1    💬 0    📌 0
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To The Best of our Knowledge is finished The longtime Wisconsin Public Radio show To The Best of Our Knowledge airs its last episode this weekend. You can listen to the stream at that link or you can listen to it over the airwaves tomorro…
28.09.2025 20:21 — 👍 15    🔁 1    💬 1    📌 1