Linkage

Congratulations to Rajeev Alur of the the University of Pennsylvania for winning the 2024 Knuth Prize (\(\mathbb{M}\)), “for his introduction of novel models of computation which provide the theoretical foundations for analysis, design, synthesis, and verification of computer systems”!

Boxed cat heads: (\(\mathbb{M}\)).

New OEIS sequence (\(\mathbb{M}\)): 1, 1, 2, 2, 5, 5, 10, 10, 26, 26, 52, 52, 130, 130, 260, 260, 677, 677, … If you want a puzzle you can try guessing what it means before clicking through. For a bigger puzzle (one I don’t have an answer to): is there a natural meaning (other than the trivial \(a(2n)\)) for the sequence 1, 2, 5, 10, 26, … that you get by removing the duplicates?

Can an equilateral convex polygon be combinatorially equivalent to the regular dodecahedron without being congruent to it (\(\mathbb{M}\))? Without convexity the answer is yes: the endododecahedron.

The Chronicle of Higher Education on the consequences of MIT dropping race as an admissions criterion (\(\mathbb{M}\), archived). It frames the story as “Black and Latino Enrollment Plunges”, which I think we can all agree is bad. But buried in the article text one finds “Asian American students account for almost half, or 47 percent, of the incoming class, an increase of six percentage points over their share from 2020 to 2023. White enrollment stayed almost unchanged.”
My conclusion is the same as when affirmative action was banned in California in 1996: affirmative action, as implemented, never took positions from white students to give to minorities. Instead, it was done at the expense of other minorities not considered disadvantaged, today and then Asian Americans. (In an earlier time it might have been Jews.) When racebased admission is banned, and with it both affirmative action for disadvantaged minorities and suppression of notconsidereddisadvantaged minorities, the suppression is lifted and we see from the difference how much they were suppressed.
The structural oppression faced by the disadvantaged minorities, causing them to be less competitive as applicants, remains. If we can no longer counterbalance it with affirmative action, we need some other way to reduce its effects. A common proxy for race is to let applicants offer hardluck stories and give spots to those whose story is the most convincing. This plausibly has the advantage of targeting the people most affected by structural oppression, but I don’t have data or links on how effectively it works.

Polysticks and polyominoes, together at last (\(\mathbb{M}\)). Alexandre Muñiz on tiling polyominoes, and then tiling their edges with polysticks.

MIT’s 2020 cancellation of all Elsevier subscriptions saves it approximately $2M/year (\(\mathbb{M}\), via) with most faculty facing few problems and supportive.

Benford’s law applied to software reliability metrics (\(\mathbb{M}\)). Seconds until first acknowledgement appears to follow the law; incident duration does not.

How to fold a bowtie (\(\mathbb{M}\)). This example shows that, unlike finite crease patterns, infinite origami crease patterns might not have a unique flatfolded shape.

Glass artist Jiyong Lee’s geometric abstractions of biological cell division (\(\mathbb{M}\)).

The polynomialtime hierarchy is infinite relative to a random oracle (\(\mathbb{M}\)), this month’s favorite theorem from Lance Fortnow.

Dave Richeson uses salt to sculpt a roofline in the shape of a hat tile, related to his construction of a foldandcut pattern from its straight skeleton (last time).

Convex Optimization in the Age of LLMs (\(\mathbb{M}\)). Ben Recht kicks off liveblogging a new course.

An infinite family of polyhedra with a single nonright angle, Michael Engen. For large \(n\) these look like ruffled disks, with increasingly highdegree trigonometric olynomials for their nonright angles.

Smooth manifolds of any dimension can be triangulated with twinwidth bounded by a function of the dimension (\(\mathbb{M}\)), Édouard Bonnet & Kristóf Huszár. Treewidth doesn’t work: 2manifolds have bounded width (just thicken a cactus graph) but for 3manifolds (even Haken manifolds) it is unbounded; see Huszár and Spreer in SoCG 2023.