Linkage

Flow lines (\(\mathbb{M}\)). Web gadget editable open source code thingy to draw streamlines of mathematical formulas, in svg format, by Maksim Surguy.
The soap bubble trope (\(\mathbb{M}\), via). Soap bubbles as a recurring theme in art, literature, and popular culture, including “the roof of the Munich Olympic Stadium, Glinda the Good Witch, the first viral ad campaign of the late Victorian era, and morose Dutch still-life paintings”.
Officially, home plate doesn’t exist (\(\mathbb{M}\)). The rules of baseball define it as a 90-45-90-90-45 pentagon with two 12” sides at one of the right angles and a 17” side between the other two, not possible.
Microsoft Academic Graph being discontinued (\(\mathbb{M}\), via). I didn’t much use that one but I live in fear that one day Google will do the same thing to Google Scholar, as they have to so many other useful but nonprofitable Google services.
My current workflow for preparing technical talk videos (\(\mathbb{M}\)):
- Use LaTeX+beamer (169 option) to make pdf talk slides
- For each slide, print open-in-Preview with custom 16x9 zero-margin layout then export to png
- Write a script and use quicktime to record 1-2 minute voiceover clips
- Compose slides and audio in iMovie, export to a huge mp4
- Use Handbrake to convert to reasonably-sized mp4
It works, but is a bit tedious and produces very dry results. The discussion includes suggestion of alternatives.
The points rotated, and the lines danced (\(\mathbb{M}\)). Video illustrating point-line duality by Sariel Har-Peled.
Letterlocking (\(\mathbb{M}\), via, see also): the art of folding your letters so intricately that readers will be forced to tear the paper to unfold and read them.
Bill Gasarch summarizes an online debate (\(\mathbb{M}\)) with Richard DeMillo and Richard Lipton, moderated by Harry Lewis, looking back at the idea of proving programs correct and at a classic 1979 paper by DeMillo, Lipton, and Perlis arguing that this idea was already problematic.
\(X+Y\) sorting (\(\mathbb{M}\)), now a Good Article on Wikipedia. This is on an old open problem in comparison sorting: can you sort pairs of elements from two sets by their sums, faster than unstructured data of the same length? It’s still an active topic of research; see e.g. Kane, Lovett, and Moran, “Near-optimal linear decision trees for \(k\)-sum and related problems”, JACM 2019.

It was not easy to persuade the GA reviewer that this article was as accessible as it could be. I have hopes of Dehn invariant also becoming a Good Article but its “Realizability” section is far more advanced.
This week I participated in the International Workshop on Graph-Theoretic Concepts in Computer Science, WG (\(\mathbb{M}\)). The 9-hour time difference made live participation awkward for me, but fortunately prerecorded contributed talks and the three invited talks (Dujmović on product structures, Samotij on independent set numeration, and Bonnet on twin-width) are linked from the conference program. The proceedings is not yet out but many preprints of papers are also linked.
“A juror says the FBI owes an apology to University of Tennessee scientist Anming Hu” (\(\mathbb{M}\), via) after putting Hu on trial for allegedly hiding ties to China despite his repeated disclosures of those ties and possibly in retaliation for his refusal to become a spy in China for the FBI. Beyond hurting US research both directly and by motivating good people to go elsewhere, this racist witch hunt has provided fuel for Chinese propaganda.
The Wikipedia “Book:” namespace for curated collections of articles is being killed off (\(\mathbb{M}\)) after the software to collate them into pdfs stopped working. I created five of these, and used two as readings for my courses. All five have moved to my user space:
Math rendering is wrong (\(\mathbb{M}\), via). This blog post from a year ago argues that, for the same reasons one might write a web site in a markup language before compiling it to html, we should also compile LaTeX to html at that time rather than using browser-side scripts (as in most deploys of MathJax or KaTeX) or conversion to images (Wikipedia). It doesn’t present a solution, but is more a call for that solution to be made.
Amazon stands by and does nothing as Chinese scammers hijack Cliff Stoll’s Klein bottle business to usurp its positive reviews (\(\mathbb{M}\), via).