Linkage

Mirzakhani and meanders (\(\mathbb{M}\)). On some more-than-coincidental similarities in formulas found by Mirzakhani for numbers of geodesics on hyperbolic surfaces and by Vincent Delecroix, Elise Goujard, Peter Zograf, and Anton Zorich in a new preprint for numbers of meanders, closed curves with a given number of intersections with a line.

Retraction of “a proof of soundness of the Raz-Safra low-degree test against entangled-player strategies, a key ingredient in the proof of the quantum low-degree test, itself a key ingredient in the \(\mathsf{MIP}^*=\mathsf{RE}\) paper” (\(\mathbb{M}\)). \(\mathsf{MIP}^*=\mathsf{RE}\) is patched and remains believed true but not fully refereed. This post provides a lot more than the standard we-found-a-bug notice: a good description of what happened, what it implies technically, and how it affects the authors and community.

For academic publishing to be trans-inclusive, authors must be allowed to retroactively change their names (\(\mathbb{M}\), via). I agree — more than once in researching Wikipedia bios I found past publications under deadnames. If the authors prefer this to be better hidden, while continuing to be credited for their past work, we should try to honor that preference.

It’s easy to point and laugh at the researcher who thought bibtex from Google scholar was usable (\(\mathbb{M}\)), but their question brings up a more serious question: why is Google’s bibtex so bad? Even the junk I get from curl -LH "Accept: application/x-bibtex" http://doi.org/... is mostly usable in comparison. I’m tempted to suggest that they go to MathSciNet for the good stuff but I’m worried they won’t have access.

Ten kinetic sculptures by Anne Lilly (\(\mathbb{M}\)).

The assembly language of satisfiability (\(\mathbb{M}\)). Why Boolean satisfiability is too low-level to work well as a way to express the kind of problems satisfiability-solvers can solve, and how satisfiability modulo theories can help.

Which regular polytopes have their vertices a subset of other regular polytopes in the same dimension (\(\mathbb{M}\))? We don’t know! The answer is closely connected to the existence of Hadamard matrices, which are famously conjectured to exist in dimensions divisible by four. A solution to the Hadamard matrix existence problem would also solve the polytope problem.

Computer scientists break traveling salesperson record (\(\mathbb{M}\)). I linked to this back in July when Karlin, Klein, and Gharan’s preprint giving a \((1/2-\varepsilon)\)-approximation to TSP first came out, but now it’s getting wider publicity in Quanta. See also an earlier (paywalled) piece on the same story in ScienceNews.

Symmetry, quasisymmetry, and kite-rhomb tessellations in the mathematical modeling of virus surface structures: IMA, Inference, Bridges (\(\mathbb{M}\)).

New German postage stamp features the missing square puzzle (\(\mathbb{M}\), see also).

R. A. Fisher and the science of hatred (\(\mathbb{M}\)). If you’ve been wondering why noted academics of yesteryear like R. A. Fisher (a major figure in statistics) and David Starr Jordan (founding president of Stanford University) have been having their names taken off things lately, the link looks like a good explainer of their views on eugenics, and why those views are now regarded as deeply racist, even for their times.

Sol LeWitt and the soapy pit (\(\mathbb{M}\), via, via2). LeWitt was an artist who in 1974 made a piece exhibiting all of the possible subsets of edges of the cube. The comfortably numbered blog examines what you get if you use these as frames for making soap films.

Funenpark (\(\mathbb{M}\)). To be clear, Funenpark is not a fun-park. It is a high-density residential development on former industrial land near Amsterdam. What interests me is their pentagonal tiles. It’s not one of the 15 monohedral pentagon tilings: the tiles have two shapes, one forming half of a regular hexagon (all angles \(> 60^\circ\)) and another surrounding the hexagons (sharp angle \(= 60^\circ\)). Still, a nice pattern.

Sometimes when I’ve been doing big literature searches on jstor (manually clicking on dozens of links because jstor’s search results don’t tell me which book is being reviewed, delayed by maybe a second or so per click so that I don’t get stopped by jstor’s anti-bot filters) I then get locked out of Google Scholar for a day or so on the same IP address because Google thinks I’m a bot. It doesn’t happen when I search Scholar directly. Has anyone else noticed this? Any idea how to avoid it? (\(\mathbb{M}\))

While I’m linking Dutch pentagonal tiling architecture, here’s an elementary school in Lochem decorated with the Mann–McLoud–Von Derau tile (\(\mathbb{M}\), via), which in 2015 became the 15th and final Euclidean monohedral pentagonal tile to be found. The link is in Dutch but Google translate works well except at one point: the school’s name, “De Garve”, means “the sheaf”, and the article remarks that this is appropriate for a pattern that looks like ears of corn.