Linkage

ICE hacked its algorithmic risk-assessment tool so it recommended detention for everyone. Research on algorithmic fairness is only applicable to the extent that the authorities use decision-making algorithms in good faith.

Drawing orthogons with an SMT solver. Brent Yorgey has been writing a sequence of blog posts on orthogonal simple polygons, considered to be equivalent when they have the same cyclic sequence of angles. They’re easy to realize from their angle sequence, but the problem becomes harder when you also want to minimize the perimeter.

Special issue of Geombinatorics on recent progress on the chromatic number of the plane. The new lower bounds on the chromatic number of the plane have now been published. This post collects links to free copies of the papers.

Some colleges cautiously embrace Wikipedia. This Chronicle of Higher Education story reports on changing attitudes of academia towards Wikipedia: where previously it had often been something to warn students away from using, now academics and Wikipedians are working more closely together.

Far-fetched mathematics on Mars (G+). Pepijn van Erp deconstructs the discrete-geometry equivalent of numerology.

Walking table. A table that walks (purely mechanically) when you push it. See also designer Wouter Scheublin’s web site.

Review of A Million Random Digits (G+). Purporting to be a review of a calculating device, this video morphs into a rant about how random numbers are the antithesis of mathematics, since they are deliberately constructed to have no patterns in them. That’s clearly debatable, but (like all of Chris Staecker’s videos) it’s entertaining and thought-provoking.

Meet the female codebreakers of Bletchley Park. The Guardian profiles Joan Joslin, Betty Webb, and Joyce Aylard.

Earthquakes, circles, and spheres (G+). Tadashi Tokieda discusses how the radical axes of each pair of any three circles (the lines through their crossing points, when the circles cross) always meet at a single point, the radical center; how the proof of this is more easily understood by lifting to 3d than in the plane, and how this is all useful for triangulating the epicenters of earthquakes. In a followup video Balls and cones he discusses a similar 3d lifting based proof of a theorem about bitangents of circles.

Academic writes 270 Wikipedia pages in a year to get female scientists noticed. The Guardian on Wikipedian Jess Wade. See also El Pais.

Inglenook Sidings (via). A puzzle in which one must assemble a randomly-determined sequence of five train cars from a group of eight, by pushing and pulling the cars on a short branched section of track. Somewhat reminiscent of sorting using stacks.

Remote access to MathSciNet (G+). While connected to a subscribing network, you can store an access code on your laptop that will remain valid for three months.

Can a scientific paper be too short? (G+). Conway and Soifer tried to make their paper on covering triangles by triangles even shorter, but their editor got fussy.

Open access and the arXiv (G+). Peter Cameron reports that Research England are disallowing arXiv preprints from meeting their requirement that all publications used for assessment purposes be open access. The stated reason is that “there is no mechanism for linking a paper on the arXiv with the published version of the paper” but this is untrue.

What happens when you let computers optimize floorplans (G+). Needs a little more architectural expertise, but interesting results despite that.

Classical alternative to quantum recommendation (G+, via). Quanta on undergrad Ewin Tang’s work with Scott Aaronson to find a fast classical algorithm for a problem on recommendation systems previously thought to only be solvable quickly by quantum computers.