Linkage

Daniel Lemire speeds up binary search using parallel data-comparison instructions (\(\mathbb{M}\), see also).

Presenting only the surname of an author is inconvenient, especially for authors from some East Asian cultures with a few very popular surnames. As posted by Joanna Ko, who has one of them.

You might know that if you make a Sierpinski tetrahedron (by subdividing a regular tetrahedron into four smaller tetrahedra at its corners and a central regular octahedron, removing the octahedron, and recursing) and then stop after finitely many levels, you get a set of vertices that from certain directions projects onto a square grid. But did you know that listing the third (projected out) coordinate for these grid points gives them the structure of a Latin square (\(\mathbb{M}\))? And that using a different Latin square than the \(2\times 2\) one as the basis for recursion can produce other fractal sets that have the same property of projecting to a square from certain directions? See section 4 of Hideki Tsuiki’s “Imaginary Cubes — Objects with Three Square Projection Images”.

Straive (a company hired by Springer for AI-copyediting journal articles) not only has an embarrassingly corporatespeak website but is sufficiently bad at mathematical typesetting to cause Niles Johnson to give up on fixing his paper and instead direct people to the arXiv version. The philosophers are also unhappy with them.

Incepta Mathematica (\(\mathbb{M}\)), a new diamond-access journal for student and amateur mathematics papers.

The Comprehensive \(\rm\LaTeX\) Symbol List (\(\mathbb{M}\)) has a new update (the first in over two years) with thousands of new symbols.

Gro-Tsen (David Madore) finds a new triangle center based on a five-point center in the projective plane, applied to the three triangle vertices and two special conjugate complex points.

Sporadic group twisty puzzles (\(\mathbb{M}\)). The one for M12 looks very playable.

Taj Ragoo inlays Islamic geometric designs into laser-engraved wood polyhedra for their Final Major Project at Arts University Plymouth. See also more flat-panel work from the project and their gallery.

“A study that claimed OpenAI’s ChatGPT can positively impact student learning has been retracted nearly one year after publication” (\(\mathbb{M}\)).

Bill Gasarch reminds us that, no matter how bad the quality of Google search has become lately, Amazon remains even worse (\(\mathbb{M}\)).

Crock pots and lightning bolts (\(\mathbb{M}\)). Adam Mastroianni on how the tendencies to shun or condone societal atrocities might be mirrored on a smaller scale by tendencies for scientists to shun or condone academic misconduct, on how in both cases making stricter rules misses the point, and on how people might develop these tendencies.

High Performance Derivative-Based Regex Matching with Intersection, Complement and Lookarounds (\(\mathbb{M}\), via), Ian Erik Varatalu, Margus Veanes, Juhan-Peep Ernits, POPL 2025. Most regex implementations don’t make intersection and complement easy to formulate, and although these operators do preserve the property of being a regular language they can blow up the preprocessing for implementations that convert their expressions into DFAs. In an associated blog post Varatalu finds many heavily-viewed stackoverflow questions asking how to work around the lack of these operations. His implementation is available under a MIT license.

New integer sequences based on stacking number bars, Christian Lawson-Perfect.