Linkage

Tricolor pyramids (\(\mathbb{M}\)). In this logic puzzle by @jsiehler, you have to 3-color hexagonal tiles avoiding 2-colored upright triangles. What interests me is not that, but the following: it’s the time-space diagram of a 3-state cellular automaton (with time flowing upward and each cell taking the color that makes the triangle below it work). But turned \(120^\circ\) it’s still the time-space diagram of the same automaton! I haven’t seen this sort of CA symmetry before.

Elsevier sends copyright threat to site for linking to Sci-Hub (\(\mathbb{M}\)). Apparently if you tell people they can find free copies of paywalled journal papers on pirate web site sci-hub, and link directly to sci-hub to make it even easier to find free copies of paywalled journal papers, you get a nasty letter from the corporate leeches who made it necessary to set up a pirate web site for free copies of paywalled journal papers . But if you go to Wikipedia you can find the link in the infobox. And it turns out that Elsevier journals themselves contain plenty of links to sci-hub (via). Sci-hub sci-hub sci-hub.

@Breakfastisready recommends the new graphic novel “Prime Suspects”, by Andrew and Jennifer Granville with illustrations by Robert J. Lewis: “It’s all about analytic number theory in metaphors.”

Mati y sus mateaventuras (\(\mathbb{M}\)), blog of popularized mathematics stories by mathematician Clara Grima and illustrator Raquel Gu (in Spanish). The latest one (from a year ago; it hasn’t updated much recently) is on Wythoff’s game.

Manu suggests reducing our impact on the planet by making conferences virtual (\(\mathbb{M}\)). Or we could, you know, publish our papers in journals instead of conferences, like everyone else, and not need to go to quite so many conferences.

Why modern integer factoring algorithms have the time bounds they do, and what would be needed to improve them (\(\mathbb{M}\)).

The University of California’s fight with Elsevier spills over to editorships (\(\mathbb{M}\)). 30 UC editors of Elsevier journals “will no longer provide editorial services” to Elsevier unless/until a satisfactory deal with Elsevier is reached.

A letter from the University of California Academic Council (\(\mathbb{M}\)) expressing their alarm at “the increasingly racialized ways in which international scholars and students—especially those from China, Iran, and Russia—are being targeted in national conversations about academic espionage” and their support for the open exchange of research.

The longest matrilineal chain in math (\(\mathbb{M}\)). Evelyn Lamb finds “five advisor-advisee chains of length four containing only women” in the Mathematics Genealogy Project, all starting with Olga Ladyzhenskaya and her student Nina Ivochkina. But her searches were haphazard so there may be longer ones still to find.

Knots and Narnias (\(\mathbb{M}\)). Riffing on a video of a Bill Thurston lecture, Jim Propp explains that when a portal to another dimension has a knotted boundary, it can actually be a portal to several other dimensions.

Dorothea Wagner wins the 2019 Konrad Zuse Medal (\(\mathbb{M}\)). This is the highest award of the German Computer Science Society, and the first time since its establishment in 1987 that the winner is a woman. Dorothea’s research includes graph drawing, route planning, optimization, and social network analysis; see her Wikipedia article for more.

Duffin–Schaeffer conjecture solved (\(\mathbb{M}\), original paper). This is about finding rational approximations to irrational numbers, like \(\pi=355/113\). Given a criterion for how good an approximation you want, depending only on the denominator (for instance, allowing only prime denominators and seeking an approximation accurate to \(\pm 1/p^{3/2}\) for denominator \(p\)) the new theorem tells you when almost all irrationals have a good-enough approximation.