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• Post #3805895

  An American privacy emergency (https://scottaaronson.blog/?p=9902): Cynthia Dwork on how new US government regulations forbidding the Census Bureau from masking its released data under differential privacy will give us less usable data, reduced protection against privacy-violating disclosures, or both. Cynthia also provides information about what you can do to help work against this.

• Post #3805894

  A reduced planar body with area greater than \(\pi\Delta^2/4\), new preprint https://arxiv.org/abs/2606.28612 by Scott Duke Kominers Here, "reduced" is a concept for two-dimensional convex bodies that is closely related to having constant width. The directional width is the distance between parallel support lines, constant width means that all directional widths are the same, thickness means the minimum directional width, and reduced means that any convex body that is a proper...

• Post #3805893

  @narain edited, thanks

• Post #3805892

  Geometric models by A. Harry Wheeler in the Smithsonian Institution: https://americanhistory.si.edu/collections/object-groups/maa-charter/geometric-models-a-harry-wheeler Another set of Wheeler models that for some reason doesn't appear in the main list: Dissected Polyhedra Transformable into Other Polyhedra, https://www.si.edu/spotlight/geometric-models-dissected-polyhedra/geometric-models-dissected-polyhedra-transformable\ For more on Wheeler, see https://en.wikipedia.org/wiki/A._Har...

• Post #3805891

  New arXiv preprint, "Sudoku Grids That Require Many Clues" (with Cindy Zhang, a UC Irvine undergraduate), https://arxiv.org/abs/2607.05728 and new blog post, "Packing Latin squares into sudoku puzzles", https://11011110.github.io/blog/2026/07/07/packing-latin-squares.html The paper uses a counting argument to show that, when you generalize sudoku to larger squares, most of the puzzle needs to be covered by clues in order to make the solution unique, leaving o...

• Post #3805890

  RE: https://fosstodon.org/@yantar92/116879675973476785 Emacs org-mode adds support for using ltx-talk in LaTeX to produce accessible slides in tagged pdf format:

• Post #3644455

  Does anyone know a reference for the following easy theorem about estimating area by counting lattice points? Let \(J\) be a region of area \(a) bounded by a Jordan curve of length \(p\). Then: \[|a - \#(\mathbb{Z}^2\cap J)| = O(p).\] Proof: sweep a unit square around the boundary of \(J\); by Cavalieri's principle the area of the swept region \(B\) is \(\le p\sqrt 2\). Consider the Voronoi cells of the integer lattice; outside of \(B\) they are completely inside or completely outside \(J\...

• Post #3599405

  Ed Pegg sent me the image below illustrating some of the minimal geometric independent dominating sets (small sets of grid points with no three in line to which no additional grid point can be added) from my EuroCG'21/CGTA'23 paper with Aichholzer and Hainzl, "Geometric dominating sets – A minimum version of the no-three-in-line problem" (https://ics.uci.edu/~eppstein/pubs/p-geomdom.html). Ed has a posting about these point sets at https://community.wolfram.com/groups/-/m/t/37...

• Post #3154428

  The American Diabetes Association has ejected from its annual meeting the editor-in-chief of its journal Diabetes Care, its former president, and three other scientists, for handing out reprints of an editorial published in the journal and critical of the US government's attacks on science: https://arstechnica.com/science/2026/06/scientists-ejected-from-diabetes-conference-for-distributing-journal-reprints/ . According to video evidence the ejected scientists "were not disruptive or di...

• Post #2063155

  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? And that using a different L...

• Post #2016369

  Pentagon Tiling Proof Solves Century-Old Math Problem, _Quanta Magazine_, https://www.quantamagazine.org/pentagon-tiling-proof-solves-century-old-math-problem-20170711/ I already posted about this a couple of months ago (https://plus.google.com/100003628603413742554/posts/dC6Qo87LouC) but now there's this nice popular-press article, and confirmation on the correctness of "the most important half of Rao's proof" by Thomas Hales.

• Post #1910478

  One week ahead of its announced deadline for major institutions to make all online content meet WCAG 2.1 A/AA accessibility standards, the US government has kicked the can down the road instead, extending the deadline to April 26, 2027: https://www.govtech.com/policy/federal-accessibility-deadline-will-be-delayed-one-year Although I was more or less on top of getting my 1600 pages of old university-hosted html content accessible, I also have a couple hundred old pdf files (for instance of paper...

• Post #1765430

  The Brouwer fixed point theorem in action, as exhibited by Github labels: If you try to define a continuous function from text colors to contrasting background colors, there will be some text colors whose background is the same as the text rather than contrasting with it. Discontinuity is necessary to avoid this. "Why some GitHub labels illegible", @MoritzFirsching, https://firsching.ch/github_labels, via https://mathstodon.xyz/@MoritzFirsching/110015890478886651 – see also ht...

• Post #1735683

  Today I learned (through a newly-added Wikipedia article) that Uruguay has a museum devoted to #origami, claimed to be the only one in the Americas: https://en.wikipedia.org/wiki/Museo_del_Origami

• Post #1687154

  Trump fires entire 24-member National Science Board: https://www.science.org/content/article/trump-fires-nsf-s-oversight-board, via https://news.ycombinator.com/item?id=47905283. This board oversees the National Science Foundation's funding of US science and advises the government on science policy, and the move is "widely seen as [Trump's] latest move to erase NSF’s independence". The National Science Foundation has also been lacking a director for the past yea...

• Post #1683340

  It's not a good time to be a program chair of a major conference: 21% of the peer reviews at ICLR (a major annual machine learning conference) were discovered to be entirely written by AI, and "more than half contained signs of AI use". This appears to be in violation of ICLR's terms of conduct, which "prohibited AI use that would have breached the confidentiality of manuscripts". The ICLR chairs write that they are planning to penalize review...

• Post #1558694

  Does anyone know what was the significance of the stella octangula to André Breton? In case anyone near Paris wants a mathematically-themed excursion, one of these shapes ornaments Breton's tomb in Batignolles: https://leblogdeclaudelothier.blogspot.com/2011/03/la-stella-octangula-sur-la-tombe-dandre.html

• Post #1095981

  ICML'26 had two groups of reviewers, one for which LLM use was forbidden and another for which it was not. Reviewers could state their preference and only those who claimed to be ok with forbidding LLM use were assigned to that group. But then, ~500 of the reviewers in the LLM-forbidden group were caught using LLMs through hidden watermarks in the papers they reviewed. As a consequence, ~400 of those reviewers had their submissions desk-rejected (~500 rejections). https://blog.icml.cc/20...

• Post #824352

  Today's useless advice about making technical online content accessible, from my university's head bureaucrat for online content accessibility bureaucracy (but I repeat myself): "I would recommend avoiding PDFs altogether. They are extremely difficult to make accessible. If PDF format is absolutely necessary, create a document in Microsoft Office and then save it as a PDF." Meanwhile, TeX Live 2026 + ltx-talk has been working for me in making pdf-format slide...

• Post #824350

  Folded cyanotype art by Fritz Horstman: https://www.fritzhorstman.com/#/folded-cyanotypes/

• Post #824348

  Two years ago in connection with SAT-solver optimization of cascading stylesheet files (https://mathstodon.xyz/@11011110/112112644240620023) I briefly mentioned the possibility that CSS might be Turing-complete, with a link to some attempts at demonstrating this via simulation of the Rule 110 cellular automaton (https://stackoverflow.com/questions/2497146/is-css-turing-complete). But these attempts were unsatisfactory for a couple of reasons: Rule 110's completeness requires an infinite...

• Post #824346

  Unexpected cutbacks in international student visa approvals by the Canadian government (far beyond their projected cutbacks) lead to program cuts and faculty layoffs at Canadian universities: https://www.cbc.ca/news/canada/british-columbia/bc-international-students-drop-study-permits-9.7139597 via https://www.metafilter.com/212675/Oopsie-BC-intl-student-visas-drop-by-66-feds-only-intended-18-cut . According to an auditor report (https://www.canada.ca/en/auditor-general/our-work/audit-reports/aud...

• Post #596064

  New blog post: Making accessible LaTeX talk slides with ltx-talk, https://11011110.github.io/blog/2026/03/01/making-accessible-latex.html

• Post #596063

  Remembering Joe Halpern, https://blog.arxiv.org/2026/02/27/remembering-joe-halpern/, focuses on Joe's pivotal role in founding and guiding the CS section of the arXiv.

• Post #596062

  A regular pentagon has five symmetry axes through one corner and its center point. Its five diagonals cross to form a smaller nested pentagon. Kevin Grace has called these ten lines (symmetry axes and diagonals) and eleven points (nested pentagon corners and center) the "Betsy Ross configuration" because of the five-point stars on the US flag. Its construction necessarily involves the square root of five, because the diagonals of a regular pentagon are longer than its sides by...

• Post #596060

  MacTeX TeX Live 2026 now available: https://www.tug.org/mactex/mactex-download.html You probably need this if you use Macs and are working on generating tagged pdf from LaTeX for accessibility. You might want to avoid this if you rely heavily on cleveref, which is broken in recent TeX Live releases.

• Post #596058

  Indonesian government blocks #Wikipedia editors from logging in over lack of official registration of the site with the government: https://rri.co.id/voice-of-indonesia/technology/2233098/wikipedia-users-in-indonesia-now-cannot-log-in-why

• Post #596057

  It's that time of the year when the plum blossoms in the alley behind my office catch the late afternoon sunlight

• Post #438869

  RE: https://mathstodon.xyz/@oantolin/116075221582512143 The cleveref apocalypse is on us: The cleveref LaTeX package is long-unmaintained and breaks on recent LaTeX versions, and an arXiv update to TeXlive means that we can no longer keep limping along using old-enough versions of TeX to avoid the problem. I haven't yet tried it but my bookmarked solution is to switch to zref-clever: https://tex.stackexchange.com/questions/733714/migration-from-cleveref-to-zref-clever

• Post #438866

  The circle packing theorem (https://en.wikipedia.org/wiki/Circle_packing_theorem): every planar graph can be represented by the tangencies of a system of non-overlapping circles. This theorem was proved by Koebe in 1936, and popularized in the 1980s by Fields medalist William Thurston as a discrete analogue to conformal mapping and uniformization. Its Wikipedia article was created by Oded Schramm in 2008, not long before his untimely mountaineering death. In his own research, Schramm found deep...