Linkage

AI experts want to end ‘black box’ algorithms in government (G+). As should the rest of us. As Greg Egan says in the comments, it’s not much better than haruspicy, and opening up the box to let us look at the bird guts ourselves wouldn’t be much of an improvement.

Predatory journals thrive because of, not in spite of, what they do for academics (G+). So combating them means eliminating the perverse incentives that send academics to them, not merely denouncing them.

Single-exponential FPT algorithms automatically lead to better-than-brute-force exact algorithms. A STOC’16 paper by Fomin, Gaspers, Lokshtanov, and Saurabh works by a really simple trick: pick a random subset, hope it’s part of the solution, and apply the FPT algorithm to the remaining unpicked elements.

The Steinhaus longimeter. Measure the approximate length of a curve by overlaying a transparency printed with several rotated grids and counting the number of times the curve crosses a grid line. In the G+ post I ask: Does it work to use the pinwheel tiling in place of a multigrid?

Lower bounds for \(k\)-median and \(k\)-means clustering. A new SODA’18 paper by Cohen-Addad, de Mesmay, Rotenberg, and Roytman uses the moment curve to show that, under the exponential time hypothesis you can’t do much better than the trivial try-all-solutions algorithm in dimensions four or higher. But you can do better in 2d. So what about 3d?

AWM Fellows. The Association for Women in Mathematics honors people (not all of them women) “who have demonstrated a sustained commitment to the support and advancement of women in the mathematical sciences”.

Nature makes a mess of open access (G+). Rather than retracting a plagiarized article they gave the author a slap on the wrist, so 22 editors of their journal resigned.

Women are going into statistics at much higher rates than into mathematics or computer science. The article cites the teamwork, welcoming environment, and plentiful role models as partial explanations.

Shape representation by zippable ribbons (G+). Improbable Research discovers some graphics people rediscovering the work of Erik Demaine, Anna Lubiw, and their parents and children.

Tiled tilings from glyptodon carapaces (G+). Glyptodons, an extinct family of mammals, were covered by a regularly-spaced array of skin-plates called scutes, each with the same pattern of bumps, which combined to make their skin look like it was covered irregularly by bumps. But if you look more closely the regularity of the pattern shows through. See links in G+ post for more explanation.

Science suffers as China’s internet censors plug holes in Great Firewall. Many academic services that we might think of as essential, like Google Scholar, are unavailable there. On the other hand, it’s at least creating pressure for viable alternatives.

Counting intersections of flats by tiled triangles (G+). I’ve been mostly avoiding the PBS Infinite Series videos because I find the presentation style too dry, and this one isn’t really an exception, but it talks about some neat math I didn’t already know about: a way to solve problems like counting lines that can touch all of four given lines in 3d, by finding 2d tilings using equilateral triangles and rhombi.

The Computing Research Association denounces the US News computer science rankings as nonsense (G+). The problem is that by using only journal publications in a field that mostly publishes in conferences, US News misses most research productivity, and severely distorts the rest.

An old link on generating Penrose tilings by planar duality from infinite line arrangements, brought to mind by a recent artwork by François Morellet depicting the same kind of line arrangement. (These line arrangements are also what the longimeter link above uses.)