Linkage

US arrests an American computer scientist for giving a talk at a conference (\(\mathbb{M}\)). It was in North Korea, on cryptocurrency, but from the story doesn’t appear to have covered anything that isn’t widely known elsewhere.

Mathematicians get riled up about mandatory diversity statements and recommendations that aboveaverage contributions to diversity be used as a hard filter for all faculty job candidates (\(\mathbb{M}\), via, via2, via3): Abigail Thompson sees mandated loyalty to political positions (such as prioritizing diversity) as antiacademic freedom, kicking off the debate. Izabella Laba disagrees but prefers institutional action to lipservice statements of good intentions and argues that unrealistic expectations on faculty (like that they all be simultaneously outstanding in teaching, research, and now also diversity) can backfire by favoring the kind of male faculty member who takes advantage of an unpaid wife as his assistant. Many others weigh in in the letters to the editor of the Notices.

Five ways to welcome women to computer science (\(\mathbb{M}\)).

Davis student newspaper provides thorough roundup of sexual harassment charges against Yuval Peres (\(\mathbb{M}\)). They missed the side drama of sockpuppets and meatpuppets cleaning this from his Wikipedia article, though, or maybe omitted it for lack of evidence connecting it to Peres himself. This is sad. Why would someone with so much to give to the field be so selfdestructive and so destructive of the lives and careers of others around him?

More stupid commercial journal publisher tricks (\(\mathbb{M}\)): Wiley won’t honor my institutional subscription unless I enable thirdparty cookies in my browser. So I can

decrease my browser security on all sites,

not read papers by László Babai on J. Graph Theory,

ask my librarian for a copy, making much more work and delay for all but maybe letting the publisher know how much negative valueadded they’re providing, or

become a pirate.
SciHub to the rescue! Yo ho!
Also while I’m picking on Wiley, how did He et al., “A polynomial‐time algorithm for simple undirected graph isomorphism” ever pass peer review for their journal Concurrency and Computation, Practice and Experience, or even a basic sanity check that it has a coherent topic that fits the mission of the journal?


The surprising link between recreational math and undecidability (\(\mathbb{M}\)). Evelyn Lamb describes how a seemingly isolated fact about Fibonacci numbers (\(F_n^2\vert F_m\Rightarrow F_n\vert m\)) led to Matiyasevich’s solution to Hilbert’s 10th problem, that there is no general algorithm for solving Diophantine equations.

My mother has a new book of poetry coming out (\(\mathbb{M}\)). I think this is her fifth, after Earthward (Finishing Line Press, 2014), Rogue Wave at Glass Beach (March Street Press, 2009), Quickening (March Street Press, 2007), and A Place Called Home (Monday Press, 1995).

This image by Adam Majewski (\(\mathbb{M}\)) shows the osculating circles of an Archimedean spiral. The spiral itself is not shown, but you can see it anyway, where the circles become dense.
It is not unusual that the circles nest. By the Tait–Kneser theorem this happens whenever the curvature along a curve is monotonic. And on most smooth curves, the curvature is monotonic except at a small number of points called vertices.

Chalkdust magazine provides a compassandstraightedge construction for the girih pattern on the cover of a recent issue (\(\mathbb{M}\)).

How archive.org preserves the history of the web, and why you should care (\(\mathbb{M}\), via). Meanwhile, Verizon sabotages efforts to archive Yahoo Groups content, in the face of their plans to shut much of it down (via, via2).

\(O(n^2)\) in Windows Management Instrumentation (\(\mathbb{M}\), via). This is why understanding algorithm analysis is important: even when the constant factors are very small (here, a nineinstruction loop), quadratic time can mean significant delays. The post also introduces “Dawson’s first law of computing: \(O(n^2)\) is the sweet spot of badly scaling algorithms: fast enough to make it into production, but slow enough to make things fall down once it gets there.”

Two recentlyposted geometry puzzles (neither of which I have seriously attempted to answer (\(\mathbb{M}\)):

John Baez collects more than you wanted to know about the statistics of random permutations (\(\mathbb{M}\)). The really pretty ones are Part 3 puzzle 8: What is the probability that a chosen element of an \(n\)element permutation lies in a cycle of length \(k\)? And part 6 puzzle 7 (don’t ask me how the numbering works): What is the expected number of \(k\)cycles in a random \(n\)element permutation?

Folding fractions (\(\mathbb{M}\)). There’s a standard compassandstraightedge construction for dividing a line segment evenly into a given number of smaller segments, and origami folding constructions are (depending on the model of what is allowed) at least as powerful, so it shouldn’t be surprising that you can fold arbitrary even subdivisions of the side of an origami square. But this construction of \(\tfrac{1}{n+1}\) from \(\tfrac{1}{n}\) by Kazuo Haga is particularly elegant.