Mark Gritter<p>"Unfolding Boxes with Local Constraints" by Long Qian, Eric Wang, Bernardo Subercaseaux, and Marijn J. H. Heule <a href="https://arxiv.org/abs/2506.01079" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">arxiv.org/abs/2506.01079</span><span class="invisible"></span></a></p><p>"We consider the problem of finding and enumerating polyominos that can be folded into multiple non-isomorphic boxes. ... In this work, we propose a new SAT-based approach that replaces these global constraints with simple local constraints that have substantially better propagation properties. Our approach dramatically improves the scalability of both computing and enumerating common box unfoldings: (i) while previous approaches could only find common unfoldings of two boxes up to area 88, ours easily scales beyond 150, and (ii) while previous approaches were only able to enumerate common unfoldings up to area 30, ours scales up to 60. This allows us to rule out 46, 54, and 58 as the smallest areas allowing a common unfolding of three boxes, thereby refuting a conjecture of Xu et al. (2017)"</p><p>Source code available, I was able to run it and find an example of a common mesh for 11x1x1 and 5x3x1 in a couple minutes. Very impressive!</p><p><a href="https://github.com/LongQianQL/CADE30-BoxUnfoldings" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">github.com/LongQianQL/CADE30-B</span><span class="invisible">oxUnfoldings</span></a></p><p><a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://mathstodon.xyz/tags/folding" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>folding</span></a></p>
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Bornach<p>Meta's Llama 4 (which is being forced on all <a href="https://masto.ai/tags/WhatsApp" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>WhatsApp</span></a> users) doesn't do any of chain-of-thought reasoning and incorrectly calculates the number of squares of one colour. Claims that a 7x7 checker board with one corner missing has 23 of one colour so makes tiling impossible but then continues on for several paragraphs about possible tiling approaches.</p><p><a href="https://masto.ai/tags/Llama4" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Llama4</span></a> <a href="https://masto.ai/tags/MetaAI" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>MetaAI</span></a> <a href="https://masto.ai/tags/AIhype" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AIhype</span></a> <a href="https://masto.ai/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://masto.ai/tags/puzzle" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>puzzle</span></a> <a href="https://masto.ai/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a></p>
Charlotte Aten<p>A fundamental result in universal algebra is the Subdirect Representation Theorem, which tells us how to decompose an algebra \(A\) into its "basic parts". Formally, we say that \(A\) is a subdirect product of \(A_1\), \(A_2\), ..., \(A_n\) when \(A\) is a subalgebra of the product<br>\[<br> A_1\times A_2\times\cdots\times A_n<br>\]<br>and for each index \(1\le i\le n\) we have for the projection \(\pi_i\) that \(\pi_i(A)=A_i\). In other words, a subdirect product "uses each component completely", but may be smaller than the full product.</p><p>A trivial circumstance is that \(\pi_i:A\to A_i\) is an isomorphism for some \(i\). The remaining components would then be superfluous. If an algebra \(A\) has the property than any way of representing it as a subdirect product is trivial in this sense, we say that \(A\) is "subdirectly irreducible".</p><p>Subdirectly irreducible algebras generalize simple algebras. Subdirectly irreducible groups include all simple groups, as well as the cyclic \(p\)-groups \(\mathbb{Z}_{p^n}\) and the Prüfer groups \(\mathbb{Z}_{p^\infty}\).</p><p>In the case of lattices, there is no known classification of the finite subdirectly irreducible (or simple) lattices. This page (<a href="https://math.chapman.edu/~jipsen/posets/si_lattices92.html" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">math.chapman.edu/~jipsen/poset</span><span class="invisible">s/si_lattices92.html</span></a>) by Peter Jipsen has diagrams showing the 92 different nontrivial subdirectly irreducible lattices of order at most 8. See any patterns?</p><p>We know that every finite subdirectly irreducible lattice can be extended to a simple lattice by adding at most two new elements (Lemma 2.3 from Grätzer's "The Congruences of a Finite Lattice", <a href="https://arxiv.org/pdf/2104.06539" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">arxiv.org/pdf/2104.06539</span><span class="invisible"></span></a>), so there must be oodles of finite simple lattices out there.</p><p><a href="https://mathstodon.xyz/tags/UniversalAlgebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>UniversalAlgebra</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://mathstodon.xyz/tags/logic" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>logic</span></a> <a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/algebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>algebra</span></a> <a href="https://mathstodon.xyz/tags/AbstractAlgebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AbstractAlgebra</span></a></p>
Bornach<p>Gemini 2.0 Flash Thinking is really messed up for the 5x5 tiling question. Pulls numbers out of the air and justifies them by saying the calculation "is very complex"</p><p>Surprisingly its answer for the 3x3 is also incorrect. There should be 4 distinct tiling patterns.<br><a href="https://masto.ai/tags/AI" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AI</span></a> <a href="https://masto.ai/tags/mathsodon" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathsodon</span></a> <a href="https://masto.ai/tags/GenerativeAI" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>GenerativeAI</span></a> <a href="https://masto.ai/tags/AIslop" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AIslop</span></a> <a href="https://masto.ai/tags/ArtificialIntelligence" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ArtificialIntelligence</span></a> <a href="https://masto.ai/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://masto.ai/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://masto.ai/tags/maths" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>maths</span></a> <a href="https://masto.ai/tags/mathematics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathematics</span></a></p>
Ross Kang<p>A post of <span class="h-card" translate="no"><a href="https://mathstodon.xyz/@11011110" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>11011110</span></a></span> has reminded me that (after a year and a half lurking here) it's never too late for me to toot and pin an intro here.</p><p>I am a Canadian mathematician in the Netherlands, and I have been based at the University of Amsterdam since 2022. I also have some rich and longstanding ties to the UK, France, and Japan.</p><p>My interests are somewhere in the nexus of Combinatorics, Probability, and Algorithms. Specifically, I like graph colouring, random graphs, and probabilistic/extremal combinatorics. I have an appreciation for randomised algorithms, graph structure theory, and discrete geometry.</p><p>Around 2020, I began taking a more active role in the community, especially in efforts towards improved fairness and openness in science. I am proud to be part of a team that founded the journal, Innovations in Graph Theory (<a href="https://igt.centre-mersenne.org/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">igt.centre-mersenne.org/</span><span class="invisible"></span></a>), that launched in 2023. (That is probably the main reason I joined mathstodon!) I have also been a coordinator since 2020 of the informal research network, A Sparse (Graphs) Coalition (<a href="https://sparse-graphs.mimuw.edu.pl/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">sparse-graphs.mimuw.edu.pl/</span><span class="invisible"></span></a>), devoted to online collaborative workshops. In 2024, I helped spearhead the MathOA Diamond Open Access Stimulus Fund (<a href="https://www.mathoa.org/diamond-open-access-stimulus-fund/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">mathoa.org/diamond-open-access</span><span class="invisible">-stimulus-fund/</span></a>).</p><p>Until now, my posts have mostly been about scientific publishing and combinatorics.</p><p><a href="https://mathstodon.xyz/tags/introduction" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>introduction</span></a> <br><a href="https://mathstodon.xyz/tags/openscience" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>openscience</span></a> <br><a href="https://mathstodon.xyz/tags/diamondopenaccess" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>diamondopenaccess</span></a> <br><a href="https://mathstodon.xyz/tags/scientificpublishing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>scientificpublishing</span></a> <br><a href="https://mathstodon.xyz/tags/openaccess" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>openaccess</span></a> <br><a href="https://mathstodon.xyz/tags/RemoteConferences" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RemoteConferences</span></a> <br><a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <br><a href="https://mathstodon.xyz/tags/graphtheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>graphtheory</span></a> <br><a href="https://mathstodon.xyz/tags/ExtremalCombinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ExtremalCombinatorics</span></a> <br><a href="https://mathstodon.xyz/tags/probability" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>probability</span></a></p>
Christ van Willegen<p>I'm busy writing a <a href="https://mastodon.nl/tags/Python" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Python</span></a> program that creates (virtual) <a href="https://mastodon.nl/tags/Lego" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Lego</span></a> <a href="https://mastodon.nl/tags/moc" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>moc</span></a> files for <a href="https://mastodon.nl/tags/LEOCad" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>LEOCad</span></a>. But, I've hit a <a href="https://mastodon.nl/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> wall, and my <a href="https://mastodon.nl/tags/maths" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>maths</span></a>-fu fails me here...</p><p>Are/is there any <a href="https://mastodon.nl/tags/programmer" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>programmer</span></a> and/or <a href="https://mastodon.nl/tags/mathematician" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathematician</span></a> who can help me? </p><p>See picture for what I'm trying to do...</p>
2something<p><span>New account, new introduction!<br><br>I'm Beth. I'm a queer mathematician who loves musical theater, webcomics, teaching math, and my cat. <br><br>Favorite areas of math: Topology, geometry, and combinatorics.<br><br>Favorite musicals: Chess, Into the Woods, Next to Normal, Sunday in the Park With George, Sweeney Todd<br><br>Favorite webcomics: this is long enough to get its own post:<br></span><a href="https://transfem.social/notes/a1ryogrga5qu00g9" rel="nofollow noopener" target="_blank">https://transfem.social/notes/a1ryogrga5qu00g9</a><span><br><br></span><a href="https://transfem.social/tags/Introduction" rel="nofollow noopener" target="_blank">#Introduction</a> <a href="https://transfem.social/tags/Queer" rel="nofollow noopener" target="_blank">#Queer</a> <a href="https://transfem.social/tags/Mathematician" rel="nofollow noopener" target="_blank">#Mathematician</a> <a href="https://transfem.social/tags/Math" rel="nofollow noopener" target="_blank">#Math</a> <a href="https://transfem.social/tags/Musicals" rel="nofollow noopener" target="_blank">#Musicals</a> <a href="https://transfem.social/tags/MusicalTheater" rel="nofollow noopener" target="_blank">#MusicalTheater</a> <a href="https://transfem.social/tags/MusicalTheatre" rel="nofollow noopener" target="_blank">#MusicalTheatre</a> <a href="https://transfem.social/tags/Webcomics" rel="nofollow noopener" target="_blank">#Webcomics</a> <a href="https://transfem.social/tags/Teaching" rel="nofollow noopener" target="_blank">#Teaching</a> <a href="https://transfem.social/tags/TeachingMath" rel="nofollow noopener" target="_blank">#TeachingMath</a> <a href="https://transfem.social/tags/Cat" rel="nofollow noopener" target="_blank">#Cat</a> <a href="https://transfem.social/tags/Cats" rel="nofollow noopener" target="_blank">#Cats</a> <a href="https://transfem.social/tags/SillyGoose" rel="nofollow noopener" target="_blank">#SillyGoose</a> <a href="https://transfem.social/tags/Topology" rel="nofollow noopener" target="_blank">#Topology</a> <a href="https://transfem.social/tags/Geometry" rel="nofollow noopener" target="_blank">#Geometry</a> <a href="https://transfem.social/tags/Combinatorics" rel="nofollow noopener" target="_blank">#Combinatorics</a> <a href="https://transfem.social/tags/Chess" rel="nofollow noopener" target="_blank">#Chess</a> <a href="https://transfem.social/tags/ChessTheMusical" rel="nofollow noopener" target="_blank">#ChessTheMusical</a> <a href="https://transfem.social/tags/IntoTheWoods" rel="nofollow noopener" target="_blank">#IntoTheWoods</a> <a href="https://transfem.social/tags/NextToNormal" rel="nofollow noopener" target="_blank">#NextToNormal</a> <a href="https://transfem.social/tags/SundayInTheParkWithGeorge" rel="nofollow noopener" target="_blank">#SundayInTheParkWithGeorge</a> <a href="https://transfem.social/tags/SweeneyTodd" rel="nofollow noopener" target="_blank">#SweeneyTodd</a> <a href="https://transfem.social/tags/PandorasTaleWiki" rel="nofollow noopener" target="_blank">#PandorasTaleWiki</a> <a href="https://transfem.social/tags/RainverseWiki" rel="nofollow noopener" target="_blank">#RainverseWiki</a></p>
Charlotte Aten<p>I've found a citation of my own work on Wikipedia for the first time!</p><p><a href="https://en.wikipedia.org/wiki/Commutative_magma" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">en.wikipedia.org/wiki/Commutat</span><span class="invisible">ive_magma</span></a></p><p>Naturally, I read this page before I wrote my rock-paper-scissors paper. It's neat to see that my own work is now the citation for something that was unsourced "original research" on Wikipedia.</p><p><a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/research" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>research</span></a> <a href="https://mathstodon.xyz/tags/Wikipedia" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Wikipedia</span></a> <a href="https://mathstodon.xyz/tags/algebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>algebra</span></a> <a href="https://mathstodon.xyz/tags/games" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>games</span></a> <a href="https://mathstodon.xyz/tags/RockPaperScissors" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RockPaperScissors</span></a> <a href="https://mathstodon.xyz/tags/AbstractAlgebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AbstractAlgebra</span></a> <a href="https://mathstodon.xyz/tags/UniversalAlgebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>UniversalAlgebra</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://mathstodon.xyz/tags/GameTheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>GameTheory</span></a></p>
Mark Gritter<p>This illustration of a 38-sided space-filling polyhedron is great! <a href="https://wolfr.am/Engel-38" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">wolfr.am/Engel-38</span><span class="invisible"></span></a></p><p>This is the largest number of sides known for any convex space-filing polyhedron. The theoretical upper bound is 92, given by <a href="https://arxiv.org/abs/0708.2114" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">arxiv.org/abs/0708.2114</span><span class="invisible"></span></a></p><p><a href="https://mathstodon.xyz/tags/polyhedra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>polyhedra</span></a> <a href="https://mathstodon.xyz/tags/spacefilling" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>spacefilling</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a></p>
Oblomov<p>A curious math problem I came up with: given a target, what's the fewest digits an integer must have (in a given base) to contain all integers from 0 to the target, as substrings?</p><p><a href="http://wok.oblomov.eu/mathesis/number-substrings/" rel="nofollow noopener" target="_blank"><span class="invisible">http://</span><span class="ellipsis">wok.oblomov.eu/mathesis/number</span><span class="invisible">-substrings/</span></a></p><p><span class="h-card"><a href="https://lemmy.ml/c/mathematics" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>mathematics</span></a></span> <span class="h-card"><a href="https://lemmy.ml/c/math" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>math@lemmy.ml</span></a></span> <span class="h-card"><a href="https://kbin.social/m/math" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>math@kbin.social</span></a></span></p><p>e.g. for a target of 19 a candidate representative would be 1011213141516171819 in base 10, that has 19 digits. Can it be done in less, or is $\sigma_10(19) = 19$?<br>Can we find a general rule? Any properties of this function?</p><p><a href="https://sociale.network/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://sociale.network/tags/maths" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>maths</span></a> <a href="https://sociale.network/tags/numberTheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>numberTheory</span></a> <a href="https://sociale.network/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a></p>
Charlotte Aten<p>Can anyone explain what's going on with the boycott of Elsevier/Springer? I finally got around to submitting the paper on partitions I posted about yesterday, and I figured that the Elsevier Journal of Combinatorial Theory, Series A, would be a reasonable choice. A friend then pointed out to me that many Americans would be upset about this, so it might hurt my future job opportunities. A similar comment was made about the Journal of Algebraic Combinatorics, which I have reviewed for.</p><p>Does anyone know the details of these boycotts? I see that people like Tim Gowers and <span class="h-card" translate="no"><a href="https://mathstodon.xyz/@johncarlosbaez" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>johncarlosbaez</span></a></span> are signatories, but how can I have a career in math without publishing in these journals? I don't like the existing system either, but I don't have enough money or presitge to just disregard it.</p><p><a href="https://mathstodon.xyz/tags/academia" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>academia</span></a> <a href="https://mathstodon.xyz/tags/Elsevier" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Elsevier</span></a> <a href="https://mathstodon.xyz/tags/Springer" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Springer</span></a> <a href="https://mathstodon.xyz/tags/publishing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>publishing</span></a> <a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a></p>
Andrej Bauer<p>Here is an idea I have been toying with occasionally, which someone must have thought of before and studied it. I would be interested in knowing of relevant references, or just buzzwords that I should enter into Google.</p><p>Consider a theory T in some formal system F. Define M_T(n) to be the number of models of T of size n, up to isomorphism, and call it the model sequence of T.</p><p>What sort of sequences are model sequences? The answer probably depends on what we take T to be. We can also ask, for instance, which sequences are model instances of an algebraic theory (first-order singature + equations), or of a theory with a single relational symbol etc.</p><p>We can also study the asymptotics of model sequences. For example, the model sequence of a theory with a single unary function symbol is O(nⁿ).</p><p>This could be a cottage insdustry, so perhaps it is? Have I reinvented the wheel?</p><p>Fun puzzle: give a first-order theory whose model sequence is 0, 1, 2, 3, 4, ...</p><p><a href="https://mathstodon.xyz/tags/logic" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>logic</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a></p>
Ross Kang<p>Just launched: a new diamond open access journal in graph theory!</p><p><a href="https://igt.centre-mersenne.org/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">igt.centre-mersenne.org/</span><span class="invisible"></span></a></p><p>published by <span class="h-card" translate="no"><a href="https://mastodon.online/@Centre_Mersenne" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>Centre_Mersenne</span></a></span> </p><p>poster: <a href="https://staff.fnwi.uva.nl/j.r.kang/posterIGT.pdf" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">staff.fnwi.uva.nl/j.r.kang/pos</span><span class="invisible">terIGT.pdf</span></a></p><p><a href="https://mathstodon.xyz/tags/diamondopenaccess" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>diamondopenaccess</span></a> <a href="https://mathstodon.xyz/tags/openaccess" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>openaccess</span></a> <a href="https://mathstodon.xyz/tags/openscience" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>openscience</span></a> <a href="https://mathstodon.xyz/tags/graphs" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>graphs</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a></p>
183231bcb<p><span>New instance (again), new introduction!<br><br>I'm Beth. I love </span><a href="https://firefish.lgbt/tags/math" rel="nofollow noopener" target="_blank">#math</a><span> , </span><a href="https://firefish.lgbt/tags/teaching" rel="nofollow noopener" target="_blank">#teaching</a><span>, </span><a href="https://firefish.lgbt/tags/MusicalTheater" rel="nofollow noopener" target="_blank">#MusicalTheater</a><span> and </span><a href="https://firefish.lgbt/tags/Webcomics" rel="nofollow noopener" target="_blank">#Webcomics</a><span>, and </span><a href="https://firefish.lgbt/tags/cats" rel="nofollow noopener" target="_blank">#cats</a><span>. I am also </span><a href="https://firefish.lgbt/tags/ace" rel="nofollow noopener" target="_blank">#ace</a><span> , </span><a href="https://firefish.lgbt/tags/aro" rel="nofollow noopener" target="_blank">#aro</a><span>, </span><a href="https://firefish.lgbt/tags/enby" rel="nofollow noopener" target="_blank">#enby</a><span>, and </span><a href="https://firefish.lgbt/tags/transfeminine" rel="nofollow noopener" target="_blank">#transfeminine</a><span> . <br><br>Favorite areas of math: </span><a href="https://firefish.lgbt/tags/geometric" rel="nofollow noopener" target="_blank">#geometric</a><span> </span><a href="https://firefish.lgbt/tags/topology" rel="nofollow noopener" target="_blank">#topology</a><span> and </span><a href="https://firefish.lgbt/tags/algebraic" rel="nofollow noopener" target="_blank">#algebraic</a><span> </span><a href="https://firefish.lgbt/tags/combinatorics" rel="nofollow noopener" target="_blank">#combinatorics</a><span><br>Favorite </span><a href="https://firefish.lgbt/tags/musicals" rel="nofollow noopener" target="_blank">#musicals</a><span>: </span><a href="https://firefish.lgbt/tags/SweeneyTodd" rel="nofollow noopener" target="_blank">#SweeneyTodd</a><span>, </span><a href="https://firefish.lgbt/tags/Chess" rel="nofollow noopener" target="_blank">#Chess</a><span>, </span><a href="https://firefish.lgbt/tags/SundayInTheParkWithGeorge" rel="nofollow noopener" target="_blank">#SundayInTheParkWithGeorge</a><span>, </span><a href="https://firefish.lgbt/tags/IntoTheWoods" rel="nofollow noopener" target="_blank">#IntoTheWoods</a><span>, </span><a href="https://firefish.lgbt/tags/NextToNormal" rel="nofollow noopener" target="_blank">#NextToNormal</a><span><br><br>Favorite webcomics: This is long enough to get its own thread:<br></span><a href="https://firefish.lgbt/notes/9hfg130tgwwx6f2s" rel="nofollow noopener" target="_blank">https://firefish.lgbt/notes/9hfg130tgwwx6f2s</a></p>
Charlotte Aten<p>I'm Charlotte Aten, a mathematician who studies combinatorics, universal algebra, and category theory. I'm a postdoc at the University of Denver where I work with <span class="h-card" translate="no"><a href="https://mathstodon.xyz/@ProfKinyon" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>ProfKinyon</span></a></span>. I write software as part of my research and have been applying my skills to the real world a bit more lately. This is my first foray into "real" social media in over a decade. I said I'd never do it again, but I can't pass up a decentralized system which is getting some mainstream traction.</p><p><a href="https://mathstodon.xyz/tags/introduction" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>introduction</span></a> <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> <a href="https://mathstodon.xyz/tags/UniversalAlgebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>UniversalAlgebra</span></a> <a href="https://mathstodon.xyz/tags/algebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>algebra</span></a> <a href="https://mathstodon.xyz/tags/CategoryTheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CategoryTheory</span></a> <a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a></p>
183231bcb<p><span>Apparently my introduction post disappeared, so let's try this again.<br><br>I'm Beth. I love </span><a href="https://calckey.lgbt/tags/math" rel="nofollow noopener" target="_blank">#math</a><span> , </span><a href="https://calckey.lgbt/tags/teaching" rel="nofollow noopener" target="_blank">#teaching</a><span>, </span><a href="https://calckey.lgbt/tags/MusicalTheater" rel="nofollow noopener" target="_blank">#MusicalTheater</a><span> and </span><a href="https://calckey.lgbt/tags/Webcomics" rel="nofollow noopener" target="_blank">#Webcomics</a><span>, and </span><a href="https://calckey.lgbt/tags/cats" rel="nofollow noopener" target="_blank">#cats</a><span>. I am also </span><a href="https://calckey.lgbt/tags/ace" rel="nofollow noopener" target="_blank">#ace</a><span> , </span><a href="https://calckey.lgbt/tags/aro" rel="nofollow noopener" target="_blank">#aro</a><span>, </span><a href="https://calckey.lgbt/tags/enby" rel="nofollow noopener" target="_blank">#enby</a><span>, and </span><a href="https://calckey.lgbt/tags/transfeminine" rel="nofollow noopener" target="_blank">#transfeminine</a><span> . <br><br>Favorite areas of math: </span><a href="https://calckey.lgbt/tags/geometric" rel="nofollow noopener" target="_blank">#geometric</a><span> </span><a href="https://calckey.lgbt/tags/topology" rel="nofollow noopener" target="_blank">#topology</a><span> and </span><a href="https://calckey.lgbt/tags/algebraic" rel="nofollow noopener" target="_blank">#algebraic</a><span> </span><a href="https://calckey.lgbt/tags/combinatorics" rel="nofollow noopener" target="_blank">#combinatorics</a><span><br>Favorite </span><a href="https://calckey.lgbt/tags/musicals" rel="nofollow noopener" target="_blank">#musicals</a><span>: </span><a href="https://calckey.lgbt/tags/SweeneyTodd" rel="nofollow noopener" target="_blank">#SweeneyTodd</a><span>, </span><a href="https://calckey.lgbt/tags/Chess" rel="nofollow noopener" target="_blank">#Chess</a><span>, </span><a href="https://calckey.lgbt/tags/SundayInTheParkWithGeorge" rel="nofollow noopener" target="_blank">#SundayInTheParkWithGeorge</a><span>, </span><a href="https://calckey.lgbt/tags/IntoTheWoods" rel="nofollow noopener" target="_blank">#IntoTheWoods</a><span>, </span><a href="https://calckey.lgbt/tags/NextToNormal" rel="nofollow noopener" target="_blank">#NextToNormal</a><span><br><br>Favorite webcomics: This is long enough to get its own thread:<br><br>RE: </span><a href="https://calckey.lgbt/notes/9g4628lnt10e5xh6" rel="nofollow noopener" target="_blank">https://calckey.lgbt/notes/9g4628lnt10e5xh6</a></p>
Karthik Srinivasan<p>Wow!! What a breathe of fresh air this paper is in the midst of suffocating levels of "AI solves everything" hype cycle. </p><p><a href="https://arxiv.org/abs/2303.10798" rel="nofollow noopener" target="_blank"><span class="invisible">https://</span><span class="">arxiv.org/abs/2303.10798</span><span class="invisible"></span></a></p><p>They have found at long last, a single tile, an "einstein", which they call a "hat"/polykite that tiles the entire plane aperiodically. </p><p>Previously the best known aperiodic tiling of the plane required at the least two different tiles, the most famous ones being the Penrose tiles, and those that adorn Alhambra. </p><p>It is all the more wonderful that the first two authors don't have any academic/research affiliations. They write somewhere in the paper, how it all started, so wonderful: </p><p>"One of the authors (Smith) began investigating the hat polykite as part of his open-ended visual exploration of shapes and their tiling properties. Working largely by hand, with the assistance of Scherphuis’s PolyForm Puzzle Solver software (<a href="http://www.jaapsch.net/puzzles/polysolver.htm" rel="nofollow noopener" target="_blank">www.jaapsch.net/puzzles/polysolver.htm</a>), he could find no obvious barriers to the construction of large patches, and yet no clear cluster of tiles that filled the plane periodically." </p><p>Why is the study of tilings such a big deal? Well, it hints at and tries to formalize various physics concepts that are of immense interest to many of us (and dare I say, even neuroscientists): quasi crystals!, possible new states of matter, emergent structures from simple units, how symmetries and asymmetries arise, stability of heterogenous media, soft matter physics, order without periodicity, criticality etc., etc., </p><p>On quasi-crystals and their search, applications, uses etc., I recommend the wonderful Paul Steinhardt's book: "The Second Kind of Impossible: The Extraordinary Quest for a New Form of Matter" </p><p><a href="https://neuromatch.social/tags/Physics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Physics</span></a> <a href="https://neuromatch.social/tags/Maths" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Maths</span></a> <a href="https://neuromatch.social/tags/Combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Combinatorics</span></a> <a href="https://neuromatch.social/tags/AperiodicTiling" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>AperiodicTiling</span></a> <a href="https://neuromatch.social/tags/PenroseTiles" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>PenroseTiles</span></a> <a href="https://neuromatch.social/tags/Einstein" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Einstein</span></a> <a href="https://neuromatch.social/tags/Emergence" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Emergence</span></a> <a href="https://neuromatch.social/tags/condensedmatter" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>condensedmatter</span></a></p>
Sean Reid<p>Hello <a href="https://mathstodon.xyz/tags/mathstodon" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathstodon</span></a>, it’s great to be here! Hard to <a href="https://mathstodon.xyz/tags/introduce" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>introduce</span></a> myself in 500 chars but here we go:</p><p>I currently work as an <a href="https://mathstodon.xyz/tags/SRE" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SRE</span></a> where I enjoy automating my job. I’ve also studied electron <a href="https://mathstodon.xyz/tags/optics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>optics</span></a> at one of the world’s largest <a href="https://mathstodon.xyz/tags/laser" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>laser</span></a> facilities, built robotic tools for the <a href="https://mathstodon.xyz/tags/Apple" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Apple</span></a> <a href="https://mathstodon.xyz/tags/FaceID" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FaceID</span></a> team, and written firmware for <a href="https://mathstodon.xyz/tags/autonomouscar" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>autonomouscar</span></a> <a href="https://mathstodon.xyz/tags/radar" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>radar</span></a> sensors.</p><p>I’m passionate about <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> , <a href="https://mathstodon.xyz/tags/gametheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>gametheory</span></a> , and <a href="https://mathstodon.xyz/tags/numbertheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>numbertheory</span></a>.</p><p>In my spare moments you can find me <a href="https://mathstodon.xyz/tags/composing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>composing</span></a> <a href="https://mathstodon.xyz/tags/music" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>music</span></a>, <a href="https://mathstodon.xyz/tags/hiking" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>hiking</span></a>, and <a href="https://mathstodon.xyz/tags/reading" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>reading</span></a>.</p>
Hal CanaryTime for a longer #introduction.
Artem Chernikov<p><a href="https://mathstodon.xyz/tags/introduction" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>introduction</span></a></p><p>I am a professor of <a href="https://mathstodon.xyz/tags/mathematics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathematics</span></a> at the University of California Los Angeles, and the director of the <a href="https://mathstodon.xyz/tags/UCLA" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>UCLA</span></a> Logic Center.</p><p>My main research interest is a branch of mathematical logic called <a href="https://mathstodon.xyz/tags/ModelTheory" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ModelTheory</span></a> and its applications to <a href="https://mathstodon.xyz/tags/algebra" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>algebra</span></a>, <a href="https://mathstodon.xyz/tags/geometry" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>geometry</span></a>, <a href="https://mathstodon.xyz/tags/combinatorics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>combinatorics</span></a> and <a href="https://mathstodon.xyz/tags/ComputerScience" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ComputerScience</span></a>.</p><p>Check out my thread about Saharon Shelah and number 4 (<a href="https://twitter.com/archernikov/status/1363159234242899970" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">twitter.com/archernikov/status</span><span class="invisible">/1363159234242899970</span></a>), or some courses that I've taught online: <a href="https://www.youtube.com/archernikov" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="">youtube.com/archernikov</span><span class="invisible"></span></a></p>
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