Posts by 11011110@mathstodon.xyz
(DIR) Post #ALXxq6NiljolbPEE6K by 11011110@mathstodon.xyz
2022-07-15T22:58:35Z
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Seriously bad data in Google's GoEmotions dataset (58K reddit comments categorized by affect): https://www.surgehq.ai//blog/30-percent-of-googles-reddit-emotions-dataset-is-mislabeled, via https://news.ycombinator.com/item?id=32090389Opinions in the post and comments vary on why the categorization was so inaccurate, including lack of context, farming it out to poorly-paid workers in countries less likely to be familiar with the specific idioms used in the comments, or maybe just that it's a hard problem.
(DIR) Post #AN9K71XvYNsg6QlVlw by 11011110@mathstodon.xyz
2022-09-02T07:01:57Z
0 likes, 1 repeats
Lithophanes, a 19th-century art medium involving backlit translucent engravings, revived via 3d printing as a single format for scientific images that blind people can read by feeling and sighted people can see: https://arstechnica.com/science/2022/08/19th-century-art-form-revived-to-make-tactile-science-graphics-for-the-blind/, based on research in https://doi.org/10.1126/sciadv.abq2640
(DIR) Post #ANQJX7AJ4Ub7pMqBXs by 11011110@mathstodon.xyz
2022-09-09T20:40:36Z
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Chegg stops pretending not to have coursework-cheating as their main business; will no longer cooperate with university cheating investigations: https://www.chronicle.com/article/some-students-use-chegg-to-cheat-the-site-has-stopped-helping-colleges-catch-them
(DIR) Post #AOPwSWGMSYk8bcy5Gi by 11011110@mathstodon.xyz
2022-10-10T06:24:10Z
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How to make yourself a copy of Wikipedia on a flash drive, usable offline: https://planetofthepaul.com/wikipedia-download-usb-flash/, via https://news.ycombinator.com/item?id=33114107
(DIR) Post #AORy6d3l665NXUgOWm by 11011110@mathstodon.xyz
2022-10-11T01:27:07Z
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The shape of a Go stone: https://gafferongames.com/post/shape_of_the_go_stone/A project from 2013 to create "a physically accurate computer simulation of a Go board and stones" starts by trying to understand the shape of the stones, settling on an intersection between two balls, modified by using a torus to bevel the sharp edge where they meet.Which sort of looks right, but a 2020 discussion suggests that a more accurate model needs to take into account how real Go stones are made: https://forums.online-go.com/t/the-shape-of-the-stones/27557
(DIR) Post #APS0V4Ikw3pd9B4qIa by 11011110@mathstodon.xyz
2022-11-10T05:22:43Z
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@xkcd This one is definitely going into my lecture notes for the next time it comes around.
(DIR) Post #ARcKMB2x8THBVMK5qq by 11011110@mathstodon.xyz
2023-01-14T00:20:06Z
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The walrus, a new and surprisingly small c/8 diagonal spaceship in Conway's Game of Life: https://conwaylife.com/wiki/WalrusAlso included: a walrus eater and a stable walrus-to-glider converterThis discovery highlights the power of modern cellular automaton pattern search codes, which integrate SAT solvers to provide deeper lookahead and quickly detect and prune sterile search branches, compared to the hardcoded limited-depth lookahead of previous software. See https://conwaylife.com/wiki/Ikpx for more.
(DIR) Post #AT2rsaaREm7jWOGldI by 11011110@mathstodon.xyz
2023-02-25T17:33:40Z
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New blog post: Isohedral Delaunay complexes, https://11011110.github.io/blog/2023/02/25/isohedral-delaunay-complexes.htmlIt's not quite possible to get a finite point set whose Delaunay cells are all symmetric to each other under Möbius transformation (some cells will be instead become part of the convex hull of the transformed copy) but you can come close.
(DIR) Post #ATIXUEkyNJ7xPQiu7E by 11011110@mathstodon.xyz
2023-03-05T07:12:15Z
1 likes, 1 repeats
Tables of Soyga: the first cellular automaton? https://stream.syscoi.com/2019/05/14/tables-of-soyga-the-first-cellular-automaton-anders-sandberg/Somehow I hadn't previously seen this 2014 post by Anders Sandberg arguing that the Book of Soyga (https://en.wikipedia.org/wiki/Book_of_Soyga), a 16th-century mystic text owned by John Dee, used cellular automaton based cryptography long before the modern study of cellular automata or cryptography.Via https://news.ycombinator.com/item?id=35023440; the Jim Reeds paper deciphering the tables from the Book of Soyga is now a deadlink, but appears likely to be "John Dee and the magic tables in the book of Soyga", https://doi.org/10.1007/1-4020-4246-9_10, http://library.pyramidal-foundational-information.com/books/The%20Book%20Of%20Soyga.pdf
(DIR) Post #AZBnWbsHWHIsjjYQ88 by 11011110@mathstodon.xyz
2023-08-28T00:02:11Z
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New blog post "A hyperbolic surface in Tokyo" on Sugimoto's pseudospherical Sundial sculpture in Otemachi, https://11011110.github.io/blog/2023/08/27/hyperbolic-surface-tokyo.html
(DIR) Post #AaF1Puq1uBqYkeaufI by 11011110@mathstodon.xyz
2023-09-28T23:32:43Z
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After resigning en masse from American Institute of Mathematical Sciences' _Journal of Geometric Mechanics_ "following a dispute with their publisher over special issues and article volume" which "would have the effect of jeopardizing scientific integrity for the sake of financial gain" the editors have launched a new journal, _Geometric Mechanics_, with ... World Scientific: https://retractionwatch.com/2023/09/28/after-resigning-en-masse-math-journal-editors-launch-new-publication/What are they thinking? As commercial publishers go, I have nothing against World Scientific, but for new journals intended to avoid financially-motivated distortion of their scientific integrity, diamond open access is the only way to go.
(DIR) Post #Ab5iK0WETPPNolgNrk by 11011110@mathstodon.xyz
2023-10-17T05:14:54Z
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A 3 state, 3 symbol Turing Machine that cannot be proven to halt or not (when starting on a blank tape) without solving a Collatz-like problem: https://www.sligocki.com/2023/10/16/bb-3-3-is-hard.html, via https://lobste.rs/s/d1piz2/bb_3_3_is_hard
(DIR) Post #AcBJVHqIoGKRTmRZwW by 11011110@mathstodon.xyz
2023-11-25T01:16:14Z
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Open access to heritage images is becoming increasingly difficult in Italy: https://diff.wikimedia.org/2023/06/05/open-access-to-heritage-images-is-becoming-increasingly-difficult-in-italy/The background to this is an Italian court case last year in which The Gallerie dell’Accademia di Venezia, a public museum in Venice, won a lawsuit forcing jigsaw puzzle maker Ravensburger to pay royalties for reproductions of far far out of copyright works by Leonardo Da Vinci: see https://communia-association.org/2023/03/01/the-vitruvian-man-a-puzzling-case-for-the-public-domain/ andhttps://news.artnet.com/news/ravensburger-da-vinci-vitruvian-man-puzzle-ruling-gallerie-dell-accademia-2276738This decision poses a threat not just to toy companies, but to Wikipedia and other users of public domain artworks.
(DIR) Post #Ak7BHMCgAH5M8f1azY by 11011110@mathstodon.xyz
2024-07-20T07:22:55Z
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If you have any goo.gl links on your web content, now would be a good time to expand them before they stop working next year. See https://www.theverge.com/2024/7/19/24201734/google-url-link-shortening-service-shut-down-support, via https://news.ycombinator.com/item?id=41014089I checked my blog and found only one, from a 2014 comment pointing to http://patmorin.tiddlyspace.com/#[[An encoding argument for multiple-choice hashing]] (a site that went defunct in late 2016 and for which that page appears not to have been archived), so that may just be dead unless @patmorin has saved it somewhere else. But at least the expanded url is more informative than the unexpanded one.Let that be a lesson not to use url encoders. They don't save you any characters on Mastodon (all urls count the same), they hide information from readers, and they're more fragile.Among the url expanders I tried in tracing this one, I found https://wheregoes.com to be the most useful, because it showed all the intermediate expansions, not just the final one to the "we're gone!" tiddlyspace page.
(DIR) Post #AqttnjmxX9iu2lv6zw by 11011110@mathstodon.xyz
2025-02-08T02:07:21Z
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@sun @quixoticgeek @th @scathach An actually useful post from this thread! All this time I've been using option-e e. Which works when I know the option-code, but this gets me more.
(DIR) Post #ArcdAHuDcZXYNYL8ka by 11011110@mathstodon.xyz
2025-03-01T20:01:04Z
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IEEE has a pseudoscience problem: https://deevybee.blogspot.com/2025/02/ieee-has-pseudoscience-problem.html, via https://retractionwatch.com/2025/03/01/weekend-reads-same-data-opposite-conclusions-death-by-ax-plastics-in-your-brain/"Unfortunately, bad science published by IEEE isn’t limited to boring applications of boring algorithms to boring data": the post goes on to describe IEEE publications about computer-enhanced ayurveda, astrology, the supernatural potential of 5G cellphone signals in scientific traditional Chinese medicine, electro-homeopathy, and even two recent papers on perpetual motion.
(DIR) Post #B2VJqmFwhwaO6FppAm by 11011110@mathstodon.xyz
2026-01-20T08:18:32Z
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@lisyarus @johncarlosbaez In this context "rational" means that the angles are rational multiples of pi (or equivalently rational numbers of degrees)
(DIR) Post #B2VJqpH7U2J7SlPIv2 by 11011110@mathstodon.xyz
2026-01-21T07:03:52Z
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@johncarlosbaez @lisyarus The explanation is that I rediscovered this old conversation while searching for material for a new Wikipedia article https://en.wikipedia.org/wiki/Triangular_billiardsIt needs more figures, and while playing around with some possibilities (which I haven't fleshed out yet) I ran into a curious phenomenon: You might expect the angles of most irrational triangles to have two independently irrational numbers. They can't have three because they sum to \(\pi\). But the first one I tried, the triangle with edge lengths 2,3,4, has only one, because its angles satisfy another unexpected relation: if \(\phi\) and \(\psi\) are the sharpest and second-sharpest angles, then \(3\phi+2\psi=\pi\). This appears to be closely related to the existence of periodic billiards paths perpendicular to the long side of this triangle.
(DIR) Post #B363suxsbinKaURk5A by 11011110@mathstodon.xyz
2026-02-07T21:51:24Z
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The Lambek–Moser theorem is a bijective equivalence between two different-looking mathematical objects: partitions of the positive integers into two disjoint subsets, and pairs of almost-inverse monotone functions from positive integers to non-negative integers.Real monotone functions are inverse when their graphs are mirror reflections across the diagonal line \(y=x\). We can define something like a graph for an integer function, a staircase curve whose lowest point above any integer on the \(x\)-axis gives the function value; then two integer functions are almost-inverse when these curves are mirror reflections. The attached image shows these two reflected staircase curves for the prime-counting function and its almost-inverse. This pair of functions corresponds to the partition of positive integers into prime and non-prime (composite or one).By using this equivalence to go from functions to partitions and back, you can sometimes get amazing formulas for sequences of integers that you might not expect to have a formula at all. For instance, the \(n\)th number that is not a \(k\)th power (for integer \(k>1\)) has the formula:\[n+\left\lfloor\sqrt[k]{n + \lfloor\sqrt[k]{n}\rfloor}\right\rfloor.\]Now a Good Article on Wikipedia, https://en.wikipedia.org/wiki/Lambek%E2%80%93Moser_theorem
(DIR) Post #B3Wdv6PteIH58yqmDw by 11011110@mathstodon.xyz
2026-02-20T19:09:57Z
1 likes, 2 repeats
I recently posted about archive.today (also archive.is, archive.ph, archive.fo, archive.li, archive.md, and archive.vn) using its archive links to launch a ddos attack against a blogger they accused of doxing them: https://mathstodon.xyz/@11011110/116028203974257264That attack triggered #Wikipedia (at least, the English part) to discuss banning archive.today links, and the ensuing discussion turned up evidence that (as part of the same dispute with the same blogger) archive.today had also tampered with its archived content to falsify certain names in old archived links: https://en.wikipedia.org/wiki/Wikipedia:Requests_for_comment/Archive.is_RFC_5#Evidence_of_altering_snapshotsThis led to a quick close of the discussion and a consensus to remove all archive.today links from Wikipedia: https://en.wikipedia.org/wiki/Wikipedia:Archive.today_guidanceFor the same reasons I have removed all archive.today links from my blog, where I had been occasionally using them as a convenient way to access paywalled content. I suggest that others remove their links as well, lest you unwittingly become part of additional ddos attacks and falsification.