Linkage

The massive influx of new users and new content to Mastodon has caused a greater number of these to be boosts of someone else’s post rather than posts of my own.

• Quanta has a nice profile of my colleague at UC Irvine, Ukrainian-born mathematician Svetlana Jitomirskaya (\(\mathbb{M}\)).

• A cardboard model of the “impossible” Penrose triangle (\(\mathbb{M}\)), with construction instructions, a printable cutout, and a demo video link, by Gerard Westendorp.

• Organic algorithm series (\(\mathbb{M}\)), artworks by Jeffrey Ventrella.

• Fatih Kızılkaya, a student of David Kempe at USC, gave an excellent talk in our theory seminar on “Plurality Veto” voting (\(\mathbb{M}\)). The idea is to count first-place votes per candidate, then let each voter cancel a single vote for their least-favorite remaining candidate (one voter at a time or simultaneously and fractionally) until only one candidate has votes left. With voters and candidates in a metric space and preferences by distance, this 3-approximates the min average distance to voters, best possible.

• Getting an academic publication cited on Wikipedia tends to lead to more citations elsewhere, and open-access publications tend to be more frequently cited on Wikipedia (\(\mathbb{M}\), via).

• Every finite colouring of the plane contains a monochromatic pair of points at an odd distance from each other (\(\mathbb{M}\)), based on a new arXiv preprint by James Davies. The paper is pretty heavy going and the linked blog post doesn’t give much detail, so providing a more generally understandable version of this looks like a challenge.

• How (not) to compute harmonic numbers (\(\mathbb{M}\)). Like for factorials, exact computation using divide-and-conquer works much better than the obvious method of sequentially adding each unit fraction. But factorials have an even faster algorithm; it’s unclear whether the same idea can be made to work for the harmonic numbers.

• Erik Demaine’s geometric folding algorithms course lectures (\(\mathbb{M}\)).

• xkcd on the bridges of Königsburg (\(\mathbb{M}\)). This one is definitely going into my lecture notes for the next time it comes around.

  

• News I didn’t know about the university I work for, UC Irvine: apparently we’re an “esports powerhouse” (\(\mathbb{M}\), archive). Definitely preferable to funneling all the alumni donations into football stadium construction! (Unlike many big US universities we don’t have a football team and I like it that way.)

• Zhao Liang asks: which polyhedra have the property that if you make them out of mirrors and stand inside, you will see a tessellation of space?

• About mandatory attendance by presenters at CS research conferences (\(\mathbb{M}\)). I just attended LATIN, a hybrid in person/online conference that ended up heavily tilted to in-person participation. In-person clearly leads to significantly greater interaction rather than mere passive reception of talks. I am very attracted to the idea of reducing the carbon footprint of my travel but in my experience we have not found a successful online replacement for that aspect of conferencing.

• Dave Richeson folds a regular octagon from a strip of paper.

• Our graduate students and their union went on strike yesterday. The LA Times has a photo-essay (\(\mathbb{M}\), archive). For the union’s demands and university’s counteroffers see this story. You can also find recent grad student and faculty salary scales online, but note that notionally at least the student salaries are for halftime work.