Linkage

Marmor Soorten, or The Book of Marble (\(\mathbb{M}\)), an Enlightenment-era full-color catalog of types of marble, to be reprinted by Taschen.

How Math Has Changed the Shape of Gerrymandering (\(\mathbb{M}\)), Quanta on the ReCom method for generating random ensembles of redistricting plans with the probability of a plan proportional to its number of spanning forests, via Markov Chain Monte Carlo, and using them as a basis of comparison to test the fairness of real redistricting plans. Moon Duchin recently spoke on the same thing at SoCG.

Erdős problems (\(\mathbb{M}\)), collected and tracked by Thomas Bloom.

Moderation Strike on Stack Overflow (\(\mathbb{M}\)) triggered by a combination of corporate insistance on allowing AI content and lying to users about what they are requiring of their moderators. This affects both MathOverflow and the TCS Stack Exchange, although MathOverflow at least is merely operated by StackExchange, not actually owned by it.

Hyperbolic Minesweeper is in \(\mathsf{P}\) (\(\mathbb{M}\)), paper from FUN 2021 by Eryk Kopczyński. As the paper shows, finite subsets of hyperbolic tilings form graphs with only logarithmic treewidth. As a consequence, problems that can be solved by dynamic programming on these graphs, such as testing the safety of moves in hyperbolic minesweeper, take polynomial time.

Online and Matching-Based Market Design (\(\mathbb{M}\)), new book edited by Federico Echenique, Nicole Immorlica, and Vijay Vazirani. The editors gave up any royalties to make it free online, but in a gratuitously annoying format where the online copy is password-locked with a publicly-announced password. The password is OMBMD_CUP. I put it into the filename of my downloaded copy so I wouldn’t lose one without the other.

Sam Mattheus and Jacques Verstraete determine the asymptotics of the Ramsey numbers \(r(4,n)\) to within a polylog (\(\mathbb{M}\)). See also Anurag Bishnoi’s blog post on the proof.

“Wikipedia has announced that it will not comply with the age verification requirements of the UK’s Online Safety Bill” (\(\mathbb{M}\), via). For more about the bill, see Wikipedia’s article on it — the issues are whether Wikipedia’s articles on sexual topics could be classified as pornography, which would trigger mandatory age verification according to the bill, and incompatibility of both age restriction and reader identification with the goals and purposes of Wikipedia.

Inside Higher Education on MAA’s insistence on holding MathFest in Florida this August (\(\mathbb{M}\), archive), in-person only, over the objections of LGBTQ+ mathematicians targeted by recently passed state anti-gay laws that prohibit people from using gender-appropriate bathrooms, forbid the mention of homosexuality, sexism, or racism in schools, and have been used to shut down parades and concerts for including people being trans in public. See also “Mathfest in Tampa: A Discussion”, MAA Focus. These sorts of events take years in advance to set up, and would incur a huge financial penalty to cancel at this late date, but the MAA already started having recriminations in 2021.

Anton Sherwood asks for monohedral tilings of the sphere with no symmetries. It’s possible, but whether it can be done with arbitrarily large numbers of tiles is unclear.

Newly promoted Wikipedia Good Article: Cantor’s isomorphism theorem (\(\mathbb{M}\)). This is the one saying that when an infinite linear ordering looks like the ordering on the rational numbers, it is the same ordering. “Looks like” means:

• It has countably many elements

• It has no minimum and no maximum

• It has another element between any two of its elements

So the rationals, the dyadic rationals, the algebraic numbers, their intersections with the open unit interval, etc. all have the same ordering.

Origami snail shells and companion octopodes.

According to Wired, giving students assignments using ChatGPT can help them become more confident in their own abilities to do better than it (\(\mathbb{M}\)).

New simple streaming algorithm for estimating the number of distinct elements in a stream (\(\mathbb{M}\)), “Distinct Elements in Streams: An Algorithm for the (Text) Book”, by Sourav Chakraborty, N. V. Vinodchandran, and Kuldeep S. Meel, updated from their ESA 2022 paper. HyperLogLog can do the same thing but the new one is maybe more suitable for teaching, and doesn’t depend on hashing. See also writeups by Knuth and Justin Jaffray.