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Making accessible LaTeX talk slides with ltx-talk
US-based academics are being required by the government and by their universities to make all online content accessible by April 24, and I think many of us have been running around trying to figure out what that means and how to do it. My university has been especially unhelpful, demanding compliance in vague terms but not telling us what standard they’re using and pointing only to Microsoft and Google’s web sites for guidance on how to improve accessibility for Microsoft and Google products. The relevant standard appears from the government links to be WCAG 2.1 AA. For those of us who have been using the LaTeX beamer package to create mathematical course lecture notes as pdf files, beamer cannot do this. The accessibility standards require tagged pdf and beamer does not have code to generate the tags correctly. But there is a solution: a replacement package, ltx-talk, that is mostly compatible with beamer. After some effort, I have succeeded in using ltx-talk to create slide decks that closely resemble my old beamer decks both in appearance and coding and that pass all automated accessibility checks in Acrobat. That makes now a good time to record what I have learned about going from beamer to accessible ltx-talk, before I forget it all again.
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Linkage
- Joe Halpern (1953–2026) (\(\mathbb{M}\)). A leader in the mathematical reasoning about knowledge, founder of the Computing Research Repository (later the CS branch of arXiv), and recipient of the Gödel Prize and Dijkstra Prize.
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Linkage
- Morphing between a polyhedron and its dual using 3d-printed scissor-link edges (\(\mathbb{M}\)) raises the question of which polyhedra can be realized in this way. The linked paper by Liao, Kiper, and Krishnan suggests that they need to be midscribed and have equal-length edges to avoid binding during the morph. A much weaker but obvious necessary condition is that for each pair of dual edges the lengths are equal. But it is unclear which polyhedra have realizations with this property.
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Linkage with bulging mussels
When I upgraded to MathJax 4.0 last October, I failed to notice that its mathematics expression explorer prevented the \(\mathbb{M}\)-links to my Mastodon posts from working. Mouseover would show the url for the link (which is why I didn’t notice) but if you clicked on it you couldn’t get anywhere unless you knew to disable the speech and Braille options in the explorer first. I’ve updated the site to disable those options by default so that the links work. You can still re-enable speech and Braille, in the context menu on any mathematical expression, under Accessibility → Speech → Generate and Accessibility → Braille → Generate (the same options you previously needed to disable to get links to work).
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Congratulations, Dr. Gangam!
I recently participated in the successful doctoral defense of Rohith Reddy Gangam, a student of Vijay Vazirani at UC Irvine. His dissertation combined research from multiple papers on three topics: robust stable matching, robust popular matching, and fair core imputations.
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Linkage
- Bridges between descriptive set theory and the theory of distributed computing through coloring geometric graphs (\(\mathbb{M}\)), Quanta, based on Anton Bernshteyn’s “Distributed algorithms, the Lovász Local Lemma, and descriptive combinatorics”, Inventiones Math. 2023.
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Invertible Bloom antimatroids
I’ve written here many times about ready lists, the familiar programming pattern in which you collect actions to be performed and pull them off the list one at a time to perform them, and about antimatroids, the algebraic structure generated by the orderings of events that you can get in this way. Here’s another example that I didn’t notice until recently, despite it being prominent in my own publications: the peeling sequences of invertible Bloom filters and invertible Bloom lookup tables.
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Linkage
- The code that revolutionized orbital simulation (\(\mathbb{M}\)), video by braintruffle on how updating velocity and position sequentially rather than in parallel causes orbital simulations to preserve symplectic invariants and thereby become much more stable.
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Winter break linkage
- Elsevier is resisting a push by Australian and NZ academics to include its journals in a uniform open-access agreement (\(\mathbb{M}\), via), and especially resisting providing “pricing transparency”. The situation may result in a boycott. As the article notes, the situation resembles past breakdowns in negotiations with Elsevier and ensuing boycotts including one from 2018 to 2023 in Germany and another from 2019 to 2021 in California.
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Regular link-irregular graphs
In two recent works, Akbar Ali, Gary Chartrand, and Ping Zhang conjecture that there is no regular link-irregular graph. Here “regular” means all vertices have equal degrees and “link-irregular” means all vertices induce non-isomorphic neighborhoods. In support of this conjecture, they show that it is true for degrees three and four. However, the probabilistic method shows this to be false for sufficiently high degrees.
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