Linkage

Talk videos from the Discrete & Computational Geometry Day in Memory of Eli Goodman and Ricky Pollack (\(\mathbb{M}\)).

Commenters baffled as Florida schools ban 54 mathematics textbooks for “prohibited topics” (\(\mathbb{M}\)). In Florida these days this seems likely to mean any hint of the existence of non-white non-cisgender people, but the quoted press release also mentions social-emotional learning, helping students develop a positive self-image during their studies and making classrooms a safe space for learning, which for some reason the US right wing wants to prevent.

American Institute of Mathematics Moves to Caltech (\(\mathbb{M}\), via). It was formerly on the site of a Fry’s Electronics store in San Jose, California (its funding came from John Fry) but Fry’s is now defunct, hence the move much farther south. The via link also discusses MathSciNet’s choice of a supporter of Mochizuki to review Mochizuki’s abc conjecture papers and failure to mention that there is any controversy with the papers. zbMATH did much better.

Who was the last holdout to publish a mathematics paper in Latin (\(\mathbb{M}\))? It appears to be Vadim Schechtman, whose “Definitio nova algebroidis verticiani” is from 2006.

Two more Wikipedia good articles (\(\mathbb{M}\)):

• Möbius strip. This was difficult because the readership spans such a wide range: there’s a lot of popular-culture material but also some nontrivial mathematics, on topics like smooth embeddability of surfaces, uniform Riemannian geometries, and group models of Lie algebras.

• Heilbronn triangle problem: if \(n\) points are placed in a square, how small is the smallest triangle we can be guaranteed to find?

Gold-model open access shuts out researchers from middle-income countries like Brazil who can’t afford publication fees and can’t obtain fee waivers (\(\mathbb{M}\), via). See also original Nature article. Of course, diamond open access has no such issues…

Lots of great geometric visualizations on Albert Chern’s twitter feed (\(\mathbb{M}\)). Here’s one: Most images of the Penrose triangle, an impossible object appearing to be made from three mutually perpendicular square beams, are drawn in an isometric perspective. But did you know that it can be drawn in three-point perspective? (It’s also that way in Penrose’s original “cohomology of impossible figures”.)

This is your semi-regular reminder that to format LaTeX with automatic internally linked theorems and lemmas, sharing numbers, there is a required order (\(\mathbb{M}\)):

1. load amsthm and hyperref

2. load cleveref

3. define theorems and lemmas

If you write LaTeX document classes that try to make things convenient by doing one of these steps out of order, you will frustrate your authors because there is no easy later fixup, and lead them to customize your class file. I’m looking at you, cccg22.cls.

Make your own gyroid (\(\mathbb{M}\)). You just need to connect together lots of hexagrams and squares in the right pattern…unfortunately I don’t think any of the snap-together polygon shapes I have are hexagrams.

Quanta article on the Kahn–Kalai conjecture (\(\mathbb{M}\)). This is the principle that, for monotonic properties of random structures (like, say, Hamiltonicity of random graphs), the threshold density for the property to hold with probability \(\tfrac12\) and the threshold density for the expected number of witnesses to be \(\tfrac12\) are within a logarithmic factor of each other. See also preprint by Jinyoung Park and Huy Tuan Pham with a proof of the conjecture.

Data Science and the High School Math Curriculum (\(\mathbb{M}\)), an open letter by California academics (including me) asserting that high school algebra is essential for STEM, and data science (albeit valuable) cannot replace it. The context is a push to water down high school math, eliminate advanced tracks, and replace math by math appreciation, in the misguided hope that this will improve diversity and remove inequities. See also reactions at Scott Aaronson’s blog and Hacker News, and a more detailed explainer of the context by Boaz Barak.

The news of Elon Musk’s impending buyout of Twitter and of his plans to release the trolls and propagandabots from their moderated chains led to a flood of new users on Mastodon. Here’s my welcome message and self-introduction.

UNESCO reports that a mathematical advantage for boys over girls at very young ages disappears as they get older, and is even reversed in some countries (\(\mathbb{M}\)).

Mathematics not trademarkable (\(\mathbb{M}\)). Somehow I missed this, but late last year the Supreme Court of Hungary ruled on a lawsuit asking to trademark the Gömböc, a 3D convex shape that, with only a single stable position, rights itself when placed on a flat surface. (Like a Weeble, but unweighted.) The answer was no: as “an answer given to a question of mathematics” with a shape “necessary for the Gömböc to self-right”, it could not be trademarked.

Computer search proves that you can always complete at least one line in standard-size Tetris (\(\mathbb{M}\), via). This is true even if the piece order is specifically chosen to make it difficult for you rather than randomly, and even if you are only allowed to rotate and drop pieces without slides or spins after they drop.