Linkage

Arranging invisible icons in quadratic time (\(\mathbb{M}\), via). Yet another instance where using a tooslow algorithm causes a UI hang, with the twist that the better solution would not be to replace it with a faster algorithm, but instead to not do the useless thing that the bad algorithm does at all.

Fun with shapes: draw an iceberg and see which way up and how deep it would float (\(\mathbb{M}\), via, via2, via3). Inspired by a twitter thread by Megan ThompsonMunson pointing out that many supposed photos or illustrations of icebergs are fake and wrong.

Draw an infinite subgraph of the 3d integer lattice in which each vertex has four coplanar neighbors, in a perpendicular plane to each of its neighbors (\(\mathbb{M}\)). This completely determines the subgraph, which is 4regular and highly symmetric. It is the graph of adjacencies of the cubes in the tetrastix structure. Does this graph have a name and history?

Gender trends in computer science authorship (\(\mathbb{M}\)). Takeaways for me (mostly from the barelyreadable Fig. 4) are:

Roughly one in four coauthors of CS research publications are currently female, up from a big dip of one in seven in the 1970s to 1990s.

Mathematics started lower and is currently more or less the same.

We are not on track to gender parity.


I’m sad that the only way to find a viewable version of the 1991 short film Not Knot (on the hyperbolic geometry of knot complements) seems to be through pirate copies (\(\mathbb{M}\)). Or you could pay $45 to Amazon for a copy on DVD. Do most people still have DVD players? At least they’re not still trying to sell it on VHS only.

On the slow spread of knowledge of nice theorems (\(\mathbb{M}\)), an amusing cartoon at the end of a longer blog post on fast graph matching heuristics.

Today’s LaTeX formatting tip (\(\mathbb{M}\)): You know that bug where amsthm + hyperref, with one numbering for theorems and lemmas and corollaries and whatever, causes
\autoref
to call them theorems even when they’re really lemmas and corollaries and whatever? If you don’t, you’re lucky. Anyway, there’s a very simple workaround: after loading amsthm and hyperref, add one more package:\usepackage[capitalize,nameinlink]{cleveref}
Then, just use
\cref
everywhere you were using\autoref
. Problem solved! 
Lloyd’s algorithm animated for 3d points (\(\mathbb{M}\)). See also the spherical version.

Applications of the no3inline problem and capsets to complexity theory (\(\mathbb{M}\)). “What is most curious to us is that for matrix multiplication, the capset related technique frustrates a better complexity upper bound, whereas [for linear algebraic circuits] it frustrates a better lower bound.”

Tensioned suspension (\(\mathbb{M}\), via): sculptures by Dan Grayber in which the weight of mechanical linkages causes them to push out against the sides of their glass enclosures, seemingly causing them to hang suspended in air. More at Grayber’s web site.