Linkage for leap day

The mysterious math of billiards tables (\(\mathbb{M}\)), Dave Richeson in Quanta.

Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn! A figure caption from Erin Wolf Chambers’ doctoral dissertation gets cited in WikiQuote. The figure it describes could be of two Great Old Ones osculating.

Non-adaptive Bellman-Ford: Yen’s improvement is optimal (\(\mathbb{M}\)), Jialu Hu and László Kozma. This new preprintimproves my paper from last year showing that a naive version of the Bellman–Ford shortest path algorithm that relaxes a predetermined sequence of edges without adapting to the results of previous relaxation steps must take cubic time. Hu and Kozma find the tight constant factor in the cubic bound. This is strong enough to show that, for this problem, randomization truly helps: there is a randomized algorithm (by Bannister & me) that uses fewer relaxation steps than Hu and Kozma’s new deterministic lower bound.

Anomalies and inconsistencies in Ioannidis’ “most influential scientists” list (\(\mathbb{M}\)). Including authors with publication dates more than a century after their deaths (or worse, more than a century before their births), non-academic journalists, institutional authors, and prolific self-citers.

The Environmental Cost of Our Conferences: The CO2 Emissions due to Travel at PODC and DISC (\(\mathbb{M}\), via), Laurent Feuilloley and Tijn de Vos, in SIGACT News . Overall recommendations are at the end of section 1: set concrete goals for carbon footprint reduction, start now in varying conference formats to do this rather than continuing to put it off, use a data-driven methodology, and set up a long-term task force to oversee the process.

Computing in Geometry and Topology, the open access computational geometry journal that I co-edit, has now been indexed by DBLP (\(\mathbb{M}\)).

Locked Polyomino Tilings (\(\mathbb{M}\)), new preprint by Jamie Tucker-Foltz on a cute recreational mathematics problem inspired by serious research on the mathematics of gerrymandering. An \(n\)-omino tiling is locked if there is no way to merge two adjacent \(n\)-ominos and then separate them in a different way into two \(n\)-ominos. See the linked discussion for the smallest locked tetromino and pentomino tilings, of \(10\times 10\) and \(20\times 20\) squares respectively.

Hexagonal tiling honeycomb. Flythrough of a foam of hexagonally-tiled horospherical bubbles in hyperbolic space.

JavaScript bloat in 2024 (\(\mathbb{M}\)). I’d love to not use any JavaScript, but that means no mathematical formulas.

Another newly promoted Wikipedia Good Article: Schönhardt polyhedron (\(\mathbb{M}\)), a six-vertex concave twisted prism whose diagonals are all outside it, preventing it from being triangulated. I learned while working on this that, when given the correct twist angle (\(30^\circ\)), its edges form a tensegrity structure that was exhibited in 1921 by Latvian-Soviet artist Karlis Johansons, seven years before Schönhardt’s mathematics publication on it.

The h-index is no longer an effective correlate of scientific reputation (\(\mathbb{M}\), via), Koltun & Hafner, PLoS One, 2021. According to the authors, in physics, the h-index no longer correlates to other measures of success such as awards from the scientific community, largely because of the huge collaborations that have come to dominate the field and that cause all of their members to have huge h-indexes.

Become a Wikipedia editor in 30 minutes (\(\mathbb{M}\)). Molly White gives video advice to help Wiki-newbies avoid getting tangled in the Wikipedia bureaucracy and start working to “prevent Wikipedia from crumbling under the weight of AI garbage spewing, and disinformation specialists’ gleeful use of the garbage”.

An architectural panel in a Chinese restaurant that looks like a Gilbert tessellation, with some speculation on the design principles that could have produced it.

A listing of freely-available online books and journal volumes (\(\mathbb{M}\)), possibly helpful to counter academic publishers who demand high access fees for bad scans of old public-domain journal articles and attempt to justify them by the preservation effort that they are clearly not doing, in cases for which the usual Google Scholar searches fail to turn up alternative copies.