<?xml version="1.0" encoding="UTF-8"?>
 <rdf:RDF xmlns="http://purl.org/rss/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:taxo="http://purl.org/rss/1.0/modules/taxonomy/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:cc="http://web.resource.org/cc/" xmlns:syn="http://purl.org/rss/1.0/modules/syndication/" xmlns:admin="http://webns.net/mvcb/">
  <channel rdf:about="http://pinboard.in">
    <title>Pinboard (Vaguery)</title>
    <link>https://pinboard.in/u:Vaguery/public/</link>
    <description>recent bookmarks from Vaguery</description>
    <items>
      <rdf:Seq>	<rdf:li rdf:resource="https://arxiv.org/abs/2406.19562"/>
	<rdf:li rdf:resource="https://hal.science/tel-05570783v1"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2604.12392"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2408.06691"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2407.11632"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2502.12717"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2605.22129"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2502.08188"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2405.08532"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2508.16441"/>
	<rdf:li rdf:resource="https://users.mccme.ru/smirnoff/papers/friezes-eng.pdf"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/math/9801088"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2204.13501"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2407.11533"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2307.14011"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2203.08856"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2206.01276"/>
	<rdf:li rdf:resource="https://dspace.cuni.cz/handle/20.500.11956/193142"/>
	<rdf:li rdf:resource="https://bookstore.ams.org/view?ProductCode=PSPUM/110"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2112.12197"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2212.11644"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2403.03280"/>
	<rdf:li rdf:resource="https://people.maths.ox.ac.uk/greenbj/papers/open-problems.pdf"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2303.06524v4"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2404.01597"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2203.01669"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2206.13877"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2310.12687"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2002.03705"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2308.15317"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2307.03525"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2308.08970"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2012.03187"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2305.01774"/>
	<rdf:li rdf:resource="https://blog.tanyakhovanova.com/2022/03/fun-with-latin-squares/"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2206.10003"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1904.05573"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1606.02982"/>
	<rdf:li rdf:resource="https://www.futilitycloset.com/2022/01/26/extra-magic/"/>
	<rdf:li rdf:resource="https://divisbyzero.com/2022/01/27/preorders-and-finite-topological-spaces/"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1202.0664"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1104.3049"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/0912.0448"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2201.04888"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1905.04490"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1805.04991"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1805.07217"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2002.02376"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1708.08975"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2010.05666"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1708.05223"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1909.12419"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2101.07608"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2103.15850"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2107.10318"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2010.11100"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2109.14777"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1801.01288"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1011.6195"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1805.03863"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1906.06069"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2105.11431"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1910.02662"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2006.14070"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2109.14774"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2107.06188"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2106.01190"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1704.00212"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/1701.08787"/>
	<rdf:li rdf:resource="https://arxiv.org/abs/2107.10167"/>
      </rdf:Seq>
    </items>
  </channel><item rdf:about="https://arxiv.org/abs/2406.19562">
    <title>[2406.19562] The Pinnacle Sets of a Graph</title>
    <dc:date>2026-06-12T12:11:33+00:00</dc:date>
    <link>https://arxiv.org/abs/2406.19562</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We introduce and study the pinnacle sets of a simple graph G with n vertices. Given a bijective vertex labeling λ:V(G)→[n], the label λ(v) of vertex v is a pinnacle of (G,λ) if λ(v)>λ(w) for all vertices w in the neighborhood of v. The pinnacle set of (G,λ) contains all the pinnacles of the labeled graph. A subset S⊆[n] is a pinnacle set of G if there exists a labeling λ such that S is the pinnacle set of (G,λ). Of interest to us is the question: Which subsets of [n] are the pinnacle sets of G? Our main results are as follows. We show that when G is connected, G has a size-k pinnacle set if and only if G has an independent set of the same size. Consequently, determining if G has a size-k pinnacle set and determining if G has a particular subset S as a pinnacle set are NP-complete problems. Nonetheless, we completely identify all the pinnacle sets of complete graphs, complete bipartite graphs, cycles and paths. We also present two techniques for deriving new pinnacle sets from old ones that imply a typical graph has many pinnacle sets. Finally, we define a poset on all the size-k pinnacle sets of G and show that it is a join semilattice. If, additionally, the poset has a minimum element, then it is a distributive lattice. We conclude with some open problems for further study.
]]></description>
<dc:subject>combinatorics fitness-landscapes peak-counting enumeration to-write-about to-cite loads-more-refs-needed</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:3f066a26b922/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:fitness-landscapes"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:peak-counting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-cite"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:loads-more-refs-needed"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://hal.science/tel-05570783v1">
    <title>Combinatorial Contemplations - Archive ouverte HAL</title>
    <dc:date>2026-05-24T17:22:15+00:00</dc:date>
    <link>https://hal.science/tel-05570783v1</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The monograph contains three Chapters. The first chapter is an introduction, outlining my philosophical views on the nature of counting, combinatorial enumeration, things and their names. It also contains a description of the classical Goulden-Jackson method which is used in the second Chapter. The second Chapter, together with the third, present my contributions as well as some recent findings of the literature. More precisely, the second Chapter is focused on the combinatorics of certain types of patterns in the molecular structure of ribonucleic acids (RNAs, one of the most important elements of biological organisms). It examines the distribution of these patterns in the real-world RNA structures and their theoretical models. The third Chapter essentially addresses two things: a new Motzkin-counted restriction of Dyck paths and a new class of Fibonacci-counted words. Not only does it provide purely scientific results, it also gives some autobiographical context. The third section of the Chapter 3 concludes the monograph by presenting a description of related works and possible directions for further research, as well as several short poems about the mesmerising process of translating thoughts into the language of words and numbers.

]]></description>
<dc:subject>mathematical-recreations combinatorics book rather-interesting RNA-folding philosophy-of-science looking-to-see</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:9c46af2bec6a/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:book"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:RNA-folding"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:philosophy-of-science"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2604.12392">
    <title>[2604.12392] Enumerations and Bijections for Stanley Polyominoes</title>
    <dc:date>2026-05-24T16:19:14+00:00</dc:date>
    <link>https://arxiv.org/abs/2604.12392</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Stanley polyominoes are a subclass of parallelogram polyominoes in which each row begins strictly to the right of the beginning of the previous row and ends strictly to the right of the end of the previous row. In this paper, we derive generating functions for Stanley polyominoes based on the numbers of columns and rows, area, semiperimeter, and numbers of interior points and edges. We also establish combinatorial connections through bijections with other combinatorial structures such as Dyck paths, skew Ferrer diagrams, and peakless Motzkin paths. As a byproduct, we answer the open question of finding a bijection between parallelogram polyominoes of area n and coin fountains with n coins in the even-numbered rows and n−k coins in the odd-numbered rows.
]]></description>
<dc:subject>combinatorics enumeration polyominoes counting discrete-mathematics Catalan-numbers representation rather-interesting</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:e41074f25cbc/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:polyominoes"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:counting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:discrete-mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:Catalan-numbers"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2408.06691">
    <title>[2408.06691] Complete ergodicity in one-dimensional reversible cellular automata</title>
    <dc:date>2026-05-24T10:53:42+00:00</dc:date>
    <link>https://arxiv.org/abs/2408.06691</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Exactly ergodicity in boundary-driven semi-infinite cellular automata (CA) are investigated. We establish all the ergodic rules in CA with 3, 4, and 5 states. We analytically prove the ergodicity for 12 rules in 3-state CA and 118320 rules in 5-state CA with any ergodic and periodic boundary condition, and numerically confirm all the other rules non-ergodic with some boundary condition. We classify ergodic rules into several patterns, which exhibit a variety of ergodic structure.
]]></description>
<dc:subject>nonlinear-dynamics cellular-automata ergodic-systems combinatorics complexology rather-interesting classification to-write-about to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:163a69784c1b/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nonlinear-dynamics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:cellular-automata"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:ergodic-systems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:complexology"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:classification"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2407.11632">
    <title>[2407.11632] Wigglyhedra</title>
    <dc:date>2026-05-24T10:47:17+00:00</dc:date>
    <link>https://arxiv.org/abs/2407.11632</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Motivated by categorical representation theory, we define the wiggly complex, whose vertices are arcs wiggling around n+2 points on a line, and whose faces are sets of wiggly arcs which are pairwise pointed and non-crossing. The wiggly complex is a (2n−1)-dimensional pseudomanifold, whose facets are wiggly pseudotriangulations. We show that wiggly pseudotriangulations are in bijection with wiggly permutations, which are permutations of [2n] avoiding the patterns (2j−1)⋯i⋯(2j) for i<2j−1 and (2j)⋯k⋯(2j−1) for k>2j. These permutations define the wiggly lattice, an induced sublattice of the weak order. We then prove that the wiggly complex is isomorphic to the boundary complex of the polar of the wigglyhedron, for which we give explicit and simple vertex and facet descriptions. Interestingly, we observe that any Cambrian associahedron is normally equivalent to a well-chosen face of the wigglyhedron. Finally, we recall the correspondence of wiggly arcs with objects in a category, and we develop categorical criteria for a subset of wiggly arcs to form a face of the wiggly complex.
]]></description>
<dc:subject>category-theory combinatorics enumeration mathematical-recreations rather-interesting to-write-about to-visualize</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:c6f72fa24635/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:category-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2502.12717">
    <title>[2502.12717] Learning the symmetric group: large from small</title>
    <dc:date>2026-05-22T11:20:50+00:00</dc:date>
    <link>https://arxiv.org/abs/2502.12717</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Machine learning explorations can make significant inroads into solving difficult problems in pure mathematics. One advantage of this approach is that mathematical datasets do not suffer from noise, but a challenge is the amount of data required to train these models and that this data can be computationally expensive to generate. Key challenges further comprise difficulty in a posteriori interpretation of statistical models and the implementation of deep and abstract mathematical problems.
We propose a method for scalable tasks, by which models trained on simpler versions of a task can then generalize to the full task. Specifically, we demonstrate that a transformer neural-network trained on predicting permutations from words formed by general transpositions in the symmetric group S10 can generalize to the symmetric group S25 with near 100\% accuracy. We also show that S10 generalizes to S16 with similar performance if we only use adjacent transpositions. We employ identity augmentation as a key tool to manage variable word lengths, and partitioned windows for training on adjacent transpositions. Finally we compare variations of the method used and discuss potential challenges with extending the method to other tasks.
]]></description>
<dc:subject>machine-learning mathematical-programming combinatorics neural-networks formal-languages to-understand to-write-about group-theory rather-interesting feature-construction approximation</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:062e950d111d/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:machine-learning"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-programming"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:neural-networks"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:formal-languages"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:group-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:feature-construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:approximation"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2605.22129">
    <title>[2605.22129] On Isotopies and hyperbolicity of weaves</title>
    <dc:date>2026-05-22T10:22:03+00:00</dc:date>
    <link>https://arxiv.org/abs/2605.22129</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[A weave is a type of textile that consists of vertical and horizontal threads, and typically it has a periodic structure. In this paper, we regard a weave as a link in the thickened torus with a diagram consisting of closed geodesics. As main results, we characterize isotopies and hyperbolicity of weaves to determine them from diagrams. Moreover, we show that there does not exist an essential Conway sphere for a weave. We use normal positions of essential surfaces of weave complements to describe them.
]]></description>
<dc:subject>topology combinatorics mathematical-recreations mathematics knot-theory to-understand enumeration consider:structural-dynamics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:67c9f5ce3c4c/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:topology"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:knot-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:structural-dynamics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2502.08188">
    <title>[2502.08188] Breakdown of Magic Numbers in Spherical Confinement</title>
    <dc:date>2026-04-20T15:54:44+00:00</dc:date>
    <link>https://arxiv.org/abs/2502.08188</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Magic numbers in finite particle systems correspond to specific system sizes that allow configurations with low free energy, often exhibiting closed surface shells to maximize the number of nearest neighbors. Since their discovery in atomic nuclei, magic numbers have been essential for understanding the number-structure-property relationship in finite clusters across different scales. However, as system size increases, the significance of magic numbers diminishes, and the precise system size at which magic number phenomena disappear remains uncertain. In this study, we investigate colloidal clusters formed through confined self-assembly. Small magic number clusters display icosahedral symmetry with closed surface shells, corresponding to pronounced free energy minima. Our findings reveal that beyond a critical system size, closed surface shells disappear, and free energy minima become less pronounced. Instead, we observe a distinct type of colloidal cluster, termed football cluster, which retains icosahedral symmetry but features lower-coordinated facets disconnected by terraces. A sphere packing model demonstrates that forming closed surface shells becomes impossible beyond a critical system size, explaining the breakdown of magic numbers in large confined systems.
]]></description>
<dc:subject>self-organization self-assembly packing molecular-design looking-to-see physics! rather-interesting colloids combinatorics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2386898a5462/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:self-organization"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:self-assembly"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:packing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:molecular-design"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:physics!"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:colloids"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2405.08532">
    <title>[2405.08532] A dynamical view of Tijdeman's solution of the chairman assignment problem</title>
    <dc:date>2026-02-20T13:53:19+00:00</dc:date>
    <link>https://arxiv.org/abs/2405.08532</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In 1980, R. Tijdeman provided an on-line algorithm that generates sequences over a finite alphabet with minimal discrepancy, that is, such that the occurrence of each letter optimally tracks its frequency. In this article, we define discrete dynamical systems generating these sequences. The dynamical systems are defined as exchanges of polytopal pieces, yielding cut and project schemes, and they code tilings of the line whose sets of vertices form model sets. We prove that these sequences of low discrepancy are natural codings of toral translations with respect to polytopal atoms, and that they generate a minimal and uniquely ergodic subshift with purely discrete spectrum. Finally, we show that the factor complexity of these sequences is of polynomial growth order nd−1, where d is the cardinality of the alphabet.
]]></description>
<dc:subject>discrepancy permutations combinatorics symbolic-dynamics to-understand to-simulate consider:higher-order-substrings algorithms probability-theory</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:37b92b01207d/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:discrepancy"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:symbolic-dynamics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:higher-order-substrings"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:probability-theory"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2508.16441">
    <title>[2508.16441] Nonstationary Markov Partitions and Multidimensional Continued Fraction Algorithms</title>
    <dc:date>2025-11-01T20:38:15+00:00</dc:date>
    <link>https://arxiv.org/abs/2508.16441</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[It is well known from results of Sina\uı and Bowen that a hyperbolic toral automorphism admits a Markov partition. Our aim is to generalize this concept to the nonstationary case, i.e., we associate Markov partitions to nonstationary sequences of toral automorphisms. Special emphasis is placed on sequences of toral automorphisms produced by strongly convergent multidimensional continued fraction algorithms. The convergence of the algorithms is expressed in terms of a Pisot type condition which yields hyperbolicity for the nonstationary dynamics. For a multidimensional continued fraction map, we first consider its natural extension, whose orbits are given by bi-infinite sequences of matrices with determinant ±1. The hyperbolicity property allows us to interpret almost every orbit of this natural extension as an Anosov mapping family, i.e., as a bi-infinite sequence of toral automorphisms with well-defined stable and unstable manifolds. We prove that this Anosov mapping family admits a bi-infinite sequence of explicit nonstationary Markov partitions. To obtain the atoms of the Markov partitions, a combinatorial structure, expressed in terms of substitutions and -adic dynamical systems, has to be superimposed on the Anosov mapping family. In particular, the atoms of the Markov partitions are geometric realizations of -adic dynamical systems, defined by suspensions of -adic Rauzy fractals. These Markov partitions then provide a symbolic model as a nonstationary edge shift for the Anosov mapping family. As a guiding example, allowing explicit realization results, we use Anosov mapping families on 2- and 3-dimensional tori associated to various versions of the Brun continued fraction algorithm.
]]></description>
<dc:subject>number-theory rewriting-systems nonlinear-dynamics rather-interesting continued-fractions computational-dynamics to-understand to-write-about consider:visualization fractals combinatorics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:88b271621dbf/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rewriting-systems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nonlinear-dynamics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:continued-fractions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computational-dynamics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:fractals"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://users.mccme.ru/smirnoff/papers/friezes-eng.pdf">
    <title>FRIEZES AND CONTINUED FRACTIONS [PDF]</title>
    <dc:date>2025-06-25T19:22:27+00:00</dc:date>
    <link>https://users.mccme.ru/smirnoff/papers/friezes-eng.pdf</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Abstract. Notes from a mini-course given at the 19th Summer School “Modern Mathematics”, Dubna, July 18–29, 2019.]]></description>
<dc:subject>mathematical-recreations mathematics John-Conway combinatorics rather-interesting to-understand number-theory enumeration</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:561a22e0c563/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:John-Conway"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/math/9801088">
    <title>[math/9801088] Shapes of polyhedra and triangulations of the sphere</title>
    <dc:date>2025-04-16T19:09:10+00:00</dc:date>
    <link>https://arxiv.org/abs/math/9801088</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The space of shapes of a polyhedron with given total angles less than 2\pi at each of its n vertices has a Kaehler metric, locally isometric to complex hyperbolic space CH^{n-3}. The metric is not complete: collisions between vertices take place a finite distance from a nonsingular point. The metric completion is a complex hyperbolic cone-manifold. In some interesting special cases, the metric completion is an orbifold. The concrete description of these spaces of shapes gives information about the combinatorial classification of triangulations of the sphere with no more than 6 triangles at a vertex.
]]></description>
<dc:subject>geometry enumeration combinatorics classics amazing-papers to-write-about to-simulate consider:squares</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:ffcbd8d7924e/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:classics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:amazing-papers"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:squares"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2204.13501">
    <title>[2204.13501] The tropical and zonotopal geometry of periodic timetables</title>
    <dc:date>2025-04-16T13:38:33+00:00</dc:date>
    <link>https://arxiv.org/abs/2204.13501</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The Periodic Event Scheduling Problem (PESP) is the standard mathematical tool for optimizing periodic timetabling problems in public transport. A solution to PESP consists of three parts: a periodic timetable, a periodic tension, and integer periodic offset values. While the space of periodic tension has received much attention in the past, we explore geometric properties of the other two components, establishing novel connections between periodic timetabling and discrete geometry. Firstly, we study the space of feasible periodic timetables, and decompose it into polytropes, i.e., polytopes that are convex both classically and in the sense of tropical geometry. We then study this decomposition and use it to outline a new heuristic for PESP, based on the tropical neighbourhood of the polytropes. Secondly, we recognize that the space of fractional cycle offsets is in fact a zonotope. We relate its zonotopal tilings back to the hyperrectangle of fractional periodic tensions and to the tropical neighbourhood of the periodic timetable space. To conclude we also use this new understanding to give tight lower bounds on the minimum width of an integral cycle basis.
]]></description>
<dc:subject>scheduling heuristics looking-to-see rather-interesting combinatorics planning periodic-solutions geometry-of-search purdy-pitchers</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:0d35ecee5f6e/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:scheduling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:heuristics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:planning"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:periodic-solutions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:geometry-of-search"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:purdy-pitchers"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2407.11533">
    <title>[2407.11533] Transforming the Challenge of Constructing Low-Discrepancy Point Sets into a Permutation Selection Problem</title>
    <dc:date>2024-12-21T17:43:43+00:00</dc:date>
    <link>https://arxiv.org/abs/2407.11533</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Low discrepancy point sets have been widely used as a tool to approximate continuous objects by discrete ones in numerical processes, for example in numerical integration. Following a century of research on the topic, it is still unclear how low the discrepancy of point sets can go; in other words, how regularly distributed can points be in a given space. Recent insights using optimization and machine learning techniques have led to substantial improvements in the construction of low-discrepancy point sets, resulting in configurations of much lower discrepancy values than previously known. Building on the optimal constructions, we present a simple way to obtain L∞-optimized placement of points that follow the same relative order as an (arbitrary) input set. Applying this approach to point sets in dimensions 2 and 3 for up to 400 and 50 points, respectively, we obtain point sets whose L∞ star discrepancies are up to 25% smaller than those of the current-best sets, and around 50% better than classical constructions such as the Fibonacci set.
]]></description>
<dc:subject>low-discrepancy-samples algorithms numerical-methods approximation rather-interesting to-write-about to-simulate combinatorics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:1f07890f97e1/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:low-discrepancy-samples"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:numerical-methods"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:approximation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2307.14011">
    <title>[2307.14011] HBS Tilings Extended: State of the Art and Novel Observations</title>
    <dc:date>2024-11-03T16:06:28+00:00</dc:date>
    <link>https://arxiv.org/abs/2307.14011</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Penrose tilings are the most famous aperiodic tilings, and they have been studied extensively. In particular, patterns composed with hexagons (H), boats (B) and stars (S) were soon exhibited and many physicists published on what they later called HBS tilings, but no article or book combines all we know about them. This work is done here, before introducing new decorations and properties including explicit substitutions. For the latter, the star comes in three versions so we have 5 prototiles in what we call the Star tileset. Yet this set yields exactly the strict HBS tilings formed using 3 tiles decorated with either the usual decorations (arrows) or Ammann bar markings for instance. Another new tileset called Gemstones is also presented, derived from the Star tileset.
]]></description>
<dc:subject>tiling aperiodic-tiling rather-interesting mathematical-recreations to-simulate combinatorics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:ff68fca26cd6/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:aperiodic-tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2203.08856">
    <title>[2203.08856] Planar Rosa : a family of quasiperiodic substitution discrete plane tilings with $2n$-fold rotational symmetry</title>
    <dc:date>2024-10-28T12:58:30+00:00</dc:date>
    <link>https://arxiv.org/abs/2203.08856</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We present Planar Rosa, a family of rhombus tilings with a 2n-fold rotational symmetry that are generated by a primitive substitution and that are also discrete plane tilings, meaning that they are obtained as a projection of a higher dimensional discrete plane. The discrete plane condition is a relaxed version of the cut-and-project condition. We also prove that the Sub Rosa substitution tilings with 2n-fold rotational symmetry defined by Kari and Rissanen do not satisfy even the weaker discrete plane condition. We prove these results for all even n≥4. This completes our previously published results for odd values of n.
]]></description>
<dc:subject>aperiodic-tiling tiling combinatorics plane-geometry rather-interesting to-understand rewriting-systems consider:animation consider:visualization</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:a005f34a88fe/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:aperiodic-tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:plane-geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rewriting-systems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:animation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2206.01276">
    <title>[2206.01276] Columnar order in random packings of $2times2$ squares on the square lattice</title>
    <dc:date>2024-10-28T12:54:11+00:00</dc:date>
    <link>https://arxiv.org/abs/2206.01276</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We study random packings of 2×2 squares with centers on the square lattice ℤ2, in which the probability of a packing is proportional to λ to the number of squares. We prove that for large λ, typical packings exhibit columnar order, in which either the centers of most tiles agree on the parity of their x-coordinate or the centers of most tiles agree on the parity of their y-coordinate. This manifests in the existence of four extremal and periodic Gibbs measures in which the rotational symmetry of the lattice is broken while the translational symmetry is only broken along a single axis. We further quantify the decay of correlations in these measures, obtaining a slow rate of exponential decay in the direction of preserved translational symmetry and a fast rate in the direction of broken translational symmetry. Lastly, we prove that every periodic Gibbs measure is a mixture of these four measures.
Additionally, our proof introduces an apparently novel extension of the chessboard estimate, from finite-volume torus measures to all infinite-volume periodic Gibbs measures.
]]></description>
<dc:subject>packing physics probability-theory combinatorics to-understand representation to-simulate consider:looking-to-see consider:animation</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2d5e7b086932/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:packing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:physics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:probability-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:animation"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://dspace.cuni.cz/handle/20.500.11956/193142">
    <title>Parking functions: What a mathematician thinks of when parking | CU Digital Repository</title>
    <dc:date>2024-10-08T19:24:42+00:00</dc:date>
    <link>https://dspace.cuni.cz/handle/20.500.11956/193142</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The basic parking problem is the following: There are n cars entering a street with n
empty parking spots and each car has a preferred spot where it tries to park. If the spot is
occupied,thecarcontinuesdrivingandparksatthefirstemptyspot(ifany). Ifallcarsare
able to park, we call the vector of their preferences a parking function. If cars are allowed
to drive also backwards up to k spots, we get the k-Naples parking functions. We present
a characterization of k-Naples parking functions formulated in terms of lattice paths. We
introduce unique-order k-Naples parking functions, present their characterization and a
calculate their number. Further, we allow cars to have different sizes. We distinguish
between two different behaviours of cars: in the first case, we get the parking sequences
and in the second case, we get the parking assortments. We introduce a problem when
the cars’ preferences are given but the order in which the cars enter the street is not. We
provide partial answers to certain related questions.]]></description>
<dc:subject>parking-functions combinatorics methodological-moves generalization rather-interesting to-write-about to-automate nudge-targets consider:classification open-problems</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:000159c37683/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:parking-functions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:methodological-moves"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:generalization"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-automate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:classification"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:open-problems"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://bookstore.ams.org/view?ProductCode=PSPUM/110">
    <title>Open Problems in Algebraic Combinatorics</title>
    <dc:date>2024-09-20T15:29:59+00:00</dc:date>
    <link>https://bookstore.ams.org/view?ProductCode=PSPUM/110</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In their preface, the editors describe algebraic combinatorics as the area of combinatorics concerned with exact, as opposed to approximate, results and which puts emphasis on interaction with other areas of mathematics, such as algebra, topology, geometry, and physics. It is a vibrant area, which saw several major developments in recent years. The goal of the 2022 conference Open Problems in Algebraic Combinatorics 2022 was to provide a forum for exchanging promising new directions and ideas. The current volume includes contributions coming from the talks at the conference, as well as a few other contributions written specifically for this volume.

The articles cover the majority of topics in algebraic combinatorics with the aim of presenting recent important research results and also important open problems and conjectures encountered in this research. The editors hope that this book will facilitate the exchange of ideas in algebraic combinatorics.

]]></description>
<dc:subject>combinatorics open-problems AMS to-read want</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:8ecf6c857226/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:open-problems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:AMS"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-read"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:want"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2112.12197">
    <title>[2112.12197] Computable Model Discovery and High-Level-Programming Approximations to Algorithmic Complexity</title>
    <dc:date>2024-09-08T15:23:21+00:00</dc:date>
    <link>https://arxiv.org/abs/2112.12197</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Motivated by algorithmic information theory, the problem of program discovery can help find candidates of underlying generative mechanisms of natural and artificial phenomena. The uncomputability of such inverse problem, however, significantly restricts a wider application of exhaustive methods. Here we present a proof of concept of an approach based on IMP, a high-level imperative programming language. Its main advantage is that conceptually complex computational routines are more succinctly expressed, unlike lower-level models such as Turing machines or cellular automata. We investigate if a more expressive higher-level programming language can be more efficient at generating approximations to algorithmic complexity of recursive functions, often of particular mathematical interest.
]]></description>
<dc:subject>algorithmic-information-theory AIT computational-complexity looking-to-see rather-interesting halting-problem enumeration combinatorics to-understand consider:FFX consider:not-worrying</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:872641e819d6/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithmic-information-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:AIT"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computational-complexity"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:halting-problem"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:FFX"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:not-worrying"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2212.11644">
    <title>[2212.11644] Poset Matrix Structure Via Partial Composition Operations</title>
    <dc:date>2024-09-05T01:03:26+00:00</dc:date>
    <link>https://arxiv.org/abs/2212.11644</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[This paper examines the structure of poset matrices by formulating a set of new construction rules for this purpose. In this direction, the technique of partial composition operation will be introduced as the basis for the construction of poset matrices of any given size by extending the combinatorial setting of species of structures to poset matrices. More specifically, three new partial composition operations that apply to poset matrices are defined as the foundation for this study. Several new structural properties derived from viewing any poset matrix and its dual in terms of these operations are highlighted.
]]></description>
<dc:subject>sorting combinatorics graph-theory matrices construction rather-interesting to-understand enumeration consider:lexicase consider:multiobjective-sets consider:probability-theory</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:0d7d0ee327b3/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:sorting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:matrices"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:lexicase"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:multiobjective-sets"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:probability-theory"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2403.03280">
    <title>[2403.03280] On the Lucky and Displacement Statistics of Stirling Permutations</title>
    <dc:date>2024-08-31T16:32:44+00:00</dc:date>
    <link>https://arxiv.org/abs/2403.03280</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Stirling permutations are parking functions, and we investigate two parking function statistics in the context of these objects: lucky cars and displacement. Among our results, we consider two extreme cases: extremely lucky Stirling permutations (those with maximally many lucky cars) and extremely unlucky Stirling permutations (those with exactly one lucky car). We show that the number of extremely lucky Stirling permutations of order n is the Catalan number Cn, and the number of extremely unlucky Stirling permutations is (n−1)!. We also give some results for luck that lies between these two extremes. Further, we establish that the displacement of any Stirling permutation of order n is n2, and we prove several results about displacement composition vectors. We conclude with directions for further study.
]]></description>
<dc:subject>combinatorics permutations rather-interesting parking-functions to-write-about to-simulate consider:sampling nudge-targets</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:d5378b7fb701/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:parking-functions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:sampling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://people.maths.ox.ac.uk/greenbj/papers/open-problems.pdf">
    <title>[untitled]</title>
    <dc:date>2024-07-23T12:31:38+00:00</dc:date>
    <link>https://people.maths.ox.ac.uk/greenbj/papers/open-problems.pdf</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[This collection of open problems has been circulated since 2018 when, encouraged by Sean Prendiville, I prepared a draft for the Arithmetic Ramsey Theory workshop in Manchester. That document was itself an expanded version of a manuscript I circulated among students starting in 2013.
The choice of problems is personal. Many are connected with topics I have worked on, but by no means all. For the most part I have avoided particularly notorious open problems (the Riemann Hypothesis, twin prime conjecture, and so on), although many of the problems are very well-known to people in the relevant field. I would like this document to stimulate further research, rather than be simply a compendium of things we do not know. For that reason I have also tried to steer clear of problems which are ‘obviously hopeless’, though progress on a number of entries does currently look a rather distant prospect.
To keep the bibliography to a reasonable length I have not given a full history
for each problem, but hopefully there is sufficient information for anyone interested
in a problem to follow up in more detail.]]></description>
<dc:subject>open-problems mathematical-recreations mathematics to-write-about consider:benchmarks number-theory combinatorics review collection</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:6079ad3d87f0/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:open-problems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:benchmarks"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:review"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:collection"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2303.06524v4">
    <title>[2303.06524v4] A heuristic search algorithm for discovering large Condorcet domains</title>
    <dc:date>2024-07-21T14:26:27+00:00</dc:date>
    <link>https://arxiv.org/abs/2303.06524v4</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The study of large Condorcet domains (CD) has been a significant area of interest in voting theory. In this paper, our goal is to search for large CDs that are hitherto unknown. With a straightforward combinatorial definition, searching for large CDs is naturally suited for algorithmic optimisations. For each value of n>2, one can ask for the size of the largest CD, thus finding the largest CDs provides an important benchmark for heuristic-based combinatorial optimisation algorithms. Despite extensive research over the past three decades, the CD sizes identified in 1996 remain the best known for many values of n. When n>8, conducting an exhaustive search becomes computationally unfeasible, thereby prompting the use of heuristic methods. To address this, we developed a novel heuristic search algorithm in which a specially designed heuristic function, backed by a lookup database, directs the search towards promising branches in the search tree. Our algorithm found new large CDs of size 1082 (surpassing the previous record of 1069) for n=10, and 2349 (improving the previous 2324) for n=11. Notably, these newly discovered CDs exhibit characteristics distinct from those of known CDs.]]></description>
<dc:subject>permutations combinatorics metaheuristics rather-interesting looking-to-see enumeration to-write-about to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:1bbab28907e4/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:metaheuristics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2404.01597">
    <title>[2404.01597] On the permutations that strongly avoid the pattern 312 or 231</title>
    <dc:date>2024-07-21T14:15:55+00:00</dc:date>
    <link>https://arxiv.org/abs/2404.01597</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In 2019, Bóna and Smith introduced the notion of \emph{strong pattern avoidance}, that is, a permutation and its square both avoid a given pattern. In this paper, we enumerate the set of permutations π which not only strongly avoid the pattern 312 or 231 but also avoid the pattern τ, for τ∈S3 and some τ∈S4. One of them is to give a positive answer to a conjecture of Archer and Geary.
]]></description>
<dc:subject>permutations combinatorics enumeration rather-interesting patterns to-write-about nudge-targets</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:e0127eba92f5/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:patterns"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2203.01669">
    <title>[2203.01669] Size Exponents of Branched Polymers/ Extension of the Isaacson-Lubensky Formula and the Application to Lattice Trees</title>
    <dc:date>2024-07-20T15:51:44+00:00</dc:date>
    <link>https://arxiv.org/abs/2203.01669</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Branched polymers can be classified into two categories that obey the different formulae:
ν=⎧⎩⎨⎪⎪⎪⎪2(1+ν0)d+22ν0for polymers withν0≥1d+1(I)for polymers withν0≤1d+1(II)
for the dilution limit in good solvents. The category II covers the exceptional polymers having fully expanded configurations. On the basis of these equalities, we discuss the size exponents of the nested architectures and the lattice trees. In particular, we compare our preceding result, νd=2=1/2, for the z=2 polymer having ν0=1/4 with the numerical result, νd=2≐0.64115, for the lattice trees generated on the 2-dimensional lattice. Our conjecture is that while both the conclusions in polymer physics and condensed matter physics are correct, the discrepancy arises from the fact that the lattice trees are constructed from less branched architectures than the branched polymers having ν0=1/4 in polymer physics. The present analysis suggests that the 2-dimensional lattice trees are the mixture of isomers having the mean ideal size exponent of ν¯0≐0.32.
]]></description>
<dc:subject>models rather-interesting combinatorics molecular-design chemistry data-structures abstraction to-write-about to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:a1db5f12a14f/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:models"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:molecular-design"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:chemistry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:data-structures"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:abstraction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2206.13877">
    <title>[2206.13877] Pattern avoiding alternating involutions</title>
    <dc:date>2024-07-03T10:12:26+00:00</dc:date>
    <link>https://arxiv.org/abs/2206.13877</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We enumerate and characterize some classes of alternating and reverse alternating involutions avoiding a single pattern of length three or four. If on one hand the case of patterns of length three is trivial, on the other hand, the length four case is more challenging and involves sequences of combinatorial interest, such as Motzkin and Fibonacci numbers.
]]></description>
<dc:subject>combinatorics permutations rather-interesting to-write-about consider:push-and-trees consider:stack-languages</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:e5f4d50593a9/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:push-and-trees"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:stack-languages"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2310.12687">
    <title>[2310.12687] Combinatorics of the Permutahedra, Associahedra, and Friends</title>
    <dc:date>2024-07-02T10:56:36+00:00</dc:date>
    <link>https://arxiv.org/abs/2310.12687</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[I present an overview of the research I have conducted for the past ten years in algebraic, bijective, enumerative, and geometric combinatorics. The two main objects I have studied are the permutahedron and the associahedron as well as the two partial orders they are related to: the weak order on permutations and the Tamari lattice. This document contains a general introduction (Chapters 1 and 2) on those objects which requires very little previous knowledge and should be accessible to non-specialist such as master students. Chapters 3 to 8 present the research I have conducted and its general context. You will find:
* a presentation of the current knowledge on Tamari interval and a precise description of the family of Tamari interval-posets which I have introduced along with the rise-contact involution to prove the symmetry of the rises and the contacts in Tamari intervals;
* my most recent results concerning q, t-enumeration of Catalan objects and Tamari intervals in relation with triangular partitions;
* the descriptions of the integer poset lattice and integer poset Hopf algebra and their relations to well known structures in algebraic combinatorics;
* the construction of the permutree lattice, the permutree Hopf algebra and permutreehedron;
* the construction of the s-weak order and s-permutahedron along with the s-Tamari lattice and s-associahedron.
Chapter 9 is dedicated to the experimental method in combinatorics research especially related to the SageMath software. Chapter 10 describes the outreach efforts I have participated in and some of my approach towards mathematical knowledge and inclusion.
]]></description>
<dc:subject>combinatorics group-theory symmetry enumeration rather-interesting trees to-write-about consider:mutation-operators consider:rewriting-systems consider:coverage</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:8b207808104e/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:group-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:symmetry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:trees"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:mutation-operators"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:rewriting-systems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:coverage"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2002.03705">
    <title>[2002.03705] Fibonacci Plays Billiards</title>
    <dc:date>2023-09-21T10:20:03+00:00</dc:date>
    <link>https://arxiv.org/abs/2002.03705</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[A chain is an ordering of the integers 1 to n such that adjacent pairs have sums of a particular form, such as squares, cubes, triangular numbers, pentagonal numbers, or Fibonacci numbers. For example 4 1 2 3 5 form a Fibonacci chain while 1 2 8 7 3 12 9 6 4 11 10 5 form a triangular chain. Since 1 + 5 is also triangular, this latter forms a triangular necklace. A search for such chains and necklaces can be facilitated by the use of paths of billiard balls on a rectangular or other polygonal billiard table.
]]></description>
<dc:subject>mathematical-recreations number-theory rather-interesting combinatorics constraint-satisfaction heuristics to-write-about to-visualize consider:arbitrary-relationships</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:9a2ab2704299/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:heuristics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:arbitrary-relationships"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2308.15317">
    <title>[2308.15317] When Can You Tile an Integer Rectangle with Integer Squares?</title>
    <dc:date>2023-09-02T15:18:45+00:00</dc:date>
    <link>https://arxiv.org/abs/2308.15317</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[This paper characterizes when an m×n rectangle, where m and n are integers, can be tiled (exactly packed) by squares where each has an integer side length of at least 2. In particular, we prove that tiling is always possible when both m and n are sufficiently large (at least 10). When one dimension m is small, the behavior is eventually periodic in n with period 1, 2, or 3. When both dimensions m,n are small, the behavior is determined computationally by an exhaustive search.
]]></description>
<dc:subject>packing combinatorics computational-geometry looking-to-see rather-interesting enumeration to-write-about nudge-targets</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2d4362d8197e/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:packing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computational-geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:looking-to-see"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2307.03525">
    <title>[2307.03525] On the uniqueness of collections of pennies and marbles</title>
    <dc:date>2023-08-22T13:26:51+00:00</dc:date>
    <link>https://arxiv.org/abs/2307.03525</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In this note we study the uniqueness problem for collections of pennies and marbles. More generally, consider a collection of unit d-spheres that may touch but not overlap. Given the existence of such a collection, one may analyse the contact graph of the collection. In particular we consider the uniqueness of the collection arising from the contact graph. Using the language of graph rigidity theory, we prove a precise characterisation of uniqueness (global rigidity) in dimensions 2 and 3 when the contact graph is additionally chordal. We then illustrate a wide range of examples in these cases. That is, we illustrate collections of marbles and pennies that can be perturbed continuously (flexible), are locally unique (rigid) and are unique (globally rigid). We also contrast these examples with the usual generic setting of graph rigidity.
]]></description>
<dc:subject>computational-geometry combinatorics enumeration packing rather-interesting to-visualize consider:isomorphism nudge-targets</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:9b8c12db5757/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computational-geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:packing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:isomorphism"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2308.08970">
    <title>[2308.08970] Geodetic Graphs: Experiments and New Constructions</title>
    <dc:date>2023-08-22T13:23:48+00:00</dc:date>
    <link>https://arxiv.org/abs/2308.08970</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In 1962 Ore initiated the study of geodetic graphs. A graph is called geodetic if the shortest path between every pair of vertices is unique. In the subsequent years a wide range of papers appeared investigating their peculiar properties. Yet, a complete classification of geodetic graphs is out of reach. 
In this work we present a program enumerating all geodetic graphs of a given size. Using our program, we succeed to find all geodetic graphs with up to 25 vertices and all regular geodetic graphs with up to 32 vertices. This leads to the discovery of two new infinite families of geodetic graphs.
]]></description>
<dc:subject>graph-theory classification rather-interesting generative-models enumeration combinatorics nudge-targets consider:classification to-write-about</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:74624b80c3f9/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:classification"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:generative-models"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:classification"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2012.03187">
    <title>[2012.03187] The number of $k$-dimensional corner-free subsets of grids</title>
    <dc:date>2023-06-27T12:34:48+00:00</dc:date>
    <link>https://arxiv.org/abs/2012.03187</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[A subset A of the k-dimensional grid {1,2,⋯,N}k is called k-dimensional corner-free if it does not contain a set of points of the form {a}∪{a+dei:1≤i≤k} for some a∈{1,2,⋯,N}k and d>0, where e1,e2,⋯,ek is the standard basis of ℝk. We define the maximum size of a k-dimensional corner-free subset of {1,2,⋯,N}k by ck(N). In this paper, we show that the number of k-dimensional corner-free subsets of the k-dimensional grid {1,2,⋯,N}k is at most 2O(ck(N)) for infinitely many values of N. Our main tool for the proof is a supersaturation result for k-dimensional corners in sets of size Θ(ck(N)) and the hypergraph container method.
]]></description>
<dc:subject>rather-interesting combinatorics open-questions set-theory hypergraphs enumeration consider:finders consider:classification</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:c588fb637308/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:open-questions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:set-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:hypergraphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:finders"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:classification"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2305.01774">
    <title>[2305.01774] Domino tilings of generalized Aztec triangles</title>
    <dc:date>2023-05-16T11:04:31+00:00</dc:date>
    <link>https://arxiv.org/abs/2305.01774</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Di Francesco introduced Aztec triangles as combinatorial objects for which their domino tilings are equinumerous with certain sets of configurations of the twenty-vertex model that are the main focus of his article. We generalize Di Francesco's construction of Aztec triangles. While we do not know whether there is again a correspondence with configurations in the twenty-vertex model, we prove closed-form product formulas for the number of domino tilings of our generalized Aztec triangles. As a special case, we obtain a proof of Di Francesco's conjectured formula for the number of domino tilings of his Aztec triangles, and thus for the number of the corresponding configurations in the twenty-vertex model.
]]></description>
<dc:subject>tiling enumeration rather-interesting combinatorics to-write-about to-simulate consider:near-misses consider:visualization</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:a760e99732e6/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:near-misses"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://blog.tanyakhovanova.com/2022/03/fun-with-latin-squares/">
    <title>Tanya Khovanova's Math Blog » Blog Archive » Fun with Latin Squares</title>
    <dc:date>2022-12-05T11:25:54+00:00</dc:date>
    <link>https://blog.tanyakhovanova.com/2022/03/fun-with-latin-squares/</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Last year, our junior PRIMES STEP group studied Latin squares. We invented a lot of different types of Latin squares and wrote a paper about it, Fun with Latin Squares. Recall that a Latin square is an n by n table containing numbers 1 through n in every cell, so that every number occurs once in each row and column. In this post, I want to talk about anti-chiece Latin squares.

]]></description>
<dc:subject>mathematical-recreations latin-suqares combinatorics constraint-satisfaction rather-interesting to-write-about consider:abstract-moves consider:general-chieces</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:9574d906e290/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:latin-suqares"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:abstract-moves"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:general-chieces"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2206.10003">
    <title>[2206.10003] Folding rotationally symmetrical tableaux via webs</title>
    <dc:date>2022-09-28T10:20:06+00:00</dc:date>
    <link>https://arxiv.org/abs/2206.10003</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Rectangular standard Young tableaux with 2 or 3 rows are in bijection with Uq(𝔰𝔩2)-webs and Uq(𝔰𝔩3)-webs respectively. When W is a web with a reflection symmetry, the corresponding tableau TW has a rotational symmetry. Folding TW transforms it into a domino tableau DW. We study the relationships between these correspondences. For 2-row tableaux, folding a rotationally symmetric tableau corresponds to "literally folding" the web along its axis of symmetry. For 3-row tableaux, we give simple algorithms, which provide direct bijective maps between symmetrical webs and domino tableaux (in both directions). These details of these algorithms reflect the intuitive idea that DW corresponds to "W modulo symmetry".
]]></description>
<dc:subject>combinatorics domino-tiling enumeration symmetry representation to-understand to-simulate consider:moves-as-text-transformations</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:41aba0acbdfd/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:domino-tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:symmetry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:moves-as-text-transformations"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1904.05573">
    <title>[1904.05573] $k$-Indivisible Noncrossing Partitions</title>
    <dc:date>2022-08-24T16:16:27+00:00</dc:date>
    <link>https://arxiv.org/abs/1904.05573</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[For a fixed integer k, we consider the set of noncrossing partitions, where both the block sizes and the difference between adjacent elements in a block is 1modk. We show that these k-indivisible noncrossing partitions can be recovered in the setting of subgroups of the symmetric group generated by (k+1)-cycles, and that the poset of k-indivisible noncrossing partitions under refinement order has many beautiful enumerative and structural properties. We encounter k-parking functions and some special Cambrian lattices on the way, and show that a special class of lattice paths constitutes a nonnesting analogue.
]]></description>
<dc:subject>combinatorics enumeration number-theory rather-interesting constraint-satisfaction to-understand to-write-about consider:visualization</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:852fab24d57f/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1606.02982">
    <title>[1606.02982] Hypergeometric Expressions for Generating Functions of Walks with Small Steps in the Quarter Plane</title>
    <dc:date>2022-07-24T12:30:43+00:00</dc:date>
    <link>https://arxiv.org/abs/1606.02982</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We study nearest-neighbors walks on the two-dimensional square lattice, that is, models of walks on ℤ2 defined by a fixed step set that is a subset of the non-zero vectors with coordinates 0, 1 or −1. We concern ourselves with the enumeration of such walks starting at the origin and constrained to remain in the quarter plane ℕ2, counted by their length and by the position of their ending point. Bousquet-Mélou and Mishna [Contemp. Math., pp. 1--39, Amer. Math. Soc., 2010] identified 19 models of walks that possess a D-finite generating function; linear differential equations have then been guessed in these cases by Bostan and Kauers [FPSAC 2009, Discrete Math. Theor. Comput. Sci. Proc., pp. 201--215, 2009]. We give here the first proof that these equations are indeed satisfied by the corresponding generating functions. As a first corollary, we prove that all these 19 generating functions can be expressed in terms of Gauss' hypergeometric functions that are intimately related to elliptic integrals. As a second corollary, we show that all the 19 generating functions are transcendental, and that among their 19×4 combinatorially meaningful specializations only four are algebraic functions.
]]></description>
<dc:subject>random-walks enumeration combinatorics rather-interesting OEIS generating-functions discrete-mathematics to-understand to-write-about consider:rediscovery</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:cdecdeb4cb27/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:random-walks"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:OEIS"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:generating-functions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:discrete-mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:rediscovery"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://www.futilitycloset.com/2022/01/26/extra-magic/">
    <title>Extra Magic - Futility Closet</title>
    <dc:date>2022-07-11T10:48:38+00:00</dc:date>
    <link>https://www.futilitycloset.com/2022/01/26/extra-magic/</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The traditional magic square is a square array of n×n distinct numbers, their magical property being that the sum of the n numbers occupying each row, column, and diagonal is the same. A variation on this theme that I introduced in 2011 is the geometric magic square in which distinct geometrical figures (usually planar shapes) occupy the cells of the array rather than numbers. The magical property enjoyed by such an array is then that the n shapes making up each row, column, and diagonal can be fitted together as in a jigsaw puzzle so as to yield (i.e. tile) a new compound shape that is the same in each case.]]></description>
<dc:subject>magic-squares combinatorics constraint-satisfaction mathematical-recreations rather-interesting polyominoes to-understand reference?</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2af70eb40c87/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:magic-squares"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:polyominoes"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:reference?"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://divisbyzero.com/2022/01/27/preorders-and-finite-topological-spaces/">
    <title>Preorders and Finite Topological Spaces – David Richeson: Division by Zero</title>
    <dc:date>2022-05-22T12:59:16+00:00</dc:date>
    <link>https://divisbyzero.com/2022/01/27/preorders-and-finite-topological-spaces/</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Today I tweeted that I had asked my topology students to find all of the different topologies of a two-point set and a three-point set. It turns out that there are three of the former and nine of the latter. (The sequence of the number of topologies for an n-point set begins 1 (for ), 3 (), 9 (), 33, 139, 718, 4535, 35979, 363083, 4717687, 79501654, 1744252509, 49872339897, 1856792610995, 89847422244493, 5637294117525695,… and is sequence A001930 in the OEIS.)
Akiva Weinberger (@akivaw) tweeted back to me saying that this is the same number of “preorders” on a set with n elements. I admitted that I’d never heard of a preorder. Then he and Joel David Hamkins (@jdhamkins) filled me in on what a preordered set is.
It found it to be pretty cool—especially the connection to topologies of finite sets. So I thought I’d share it here on my blog.
]]></description>
<dc:subject>set-theory combinatorics rather-interesting enumeration explanation discrete-mathematics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:49ae06dc764a/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:set-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:explanation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:discrete-mathematics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1202.0664">
    <title>[1202.0664] From heaps of matches to the limits of computability</title>
    <dc:date>2022-05-04T12:56:11+00:00</dc:date>
    <link>https://arxiv.org/abs/1202.0664</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We study so-called invariant games played with a fixed number d of heaps of matches. A game is described by a finite list  of integer vectors of length d specifying the legal moves. A move consists in changing the current game-state by adding one of the vectors in , provided all elements of the resulting vector are nonnegative. For instance, in a two-heap game, the vector (1,−2) would mean adding one match to the first heap and removing two matches from the second heap. If (1,−2)∈, such a move would be permitted provided there are at least two matches in the second heap. Two players take turns, and a player unable to make a move loses. We show that these games embrace computational universality, and that therefore a number of basic questions about them are algorithmically undecidable. In particular, we prove that there is no algorithm that takes two games  and ′ (with the same number of heaps) as input, and determines whether or not they are equivalent in the sense that every starting-position which is a first player win in one of the games is a first player win in the other.
]]></description>
<dc:subject>game-theory combinatorics to-understand computation consider:wth</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:5ec73d42f4da/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:game-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:wth"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1104.3049">
    <title>[1104.3049] When only the last one will do</title>
    <dc:date>2022-05-04T12:54:07+00:00</dc:date>
    <link>https://arxiv.org/abs/1104.3049</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[An unknown positive number of items arrive at independent uniformly distributed times in the interval [0,1] to a selector, whose task is to pick online the last one. We show that under the assumption of an adversary determining the number of items, there exists a game-theoretical equilibrium, in other words the selector and the adversary both possess optimal strategies. The probability of success of the selector with the optimal strategy is estimated numerically to 0.352917000207196.
]]></description>
<dc:subject>game-theory combinatorics planning decision-making optimization to-understand to-write-about consider:simulation</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:01eebcbf3a24/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:game-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:planning"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:decision-making"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:optimization"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:simulation"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/0912.0448">
    <title>[0912.0448] The strange algebra of combinatorial games</title>
    <dc:date>2022-05-04T12:51:05+00:00</dc:date>
    <link>https://arxiv.org/abs/0912.0448</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We present an algebraic framework for the analysis of combinatorial games. This framework embraces the classical theory of partizan games as well as a number of misere games, comply-constrain games, and card games that have been studied more recently. It focuses on the construction of the quotient monoid of a game, an idea that has been successively applied to several classes of games.
]]></description>
<dc:subject>game-theory category-theory combinatorics to-understand representation algebra</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:f1981291c1af/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:game-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:category-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algebra"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2201.04888">
    <title>[2201.04888] Generating graphs randomly</title>
    <dc:date>2022-03-12T13:08:54+00:00</dc:date>
    <link>https://arxiv.org/abs/2201.04888</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Graphs are used in many disciplines to model the relationships that exist between objects in a complex discrete system. Researchers may wish to compare a network of interest to a "typical" graph from a family (or ensemble) of graphs which are similar in some way. One way to do this is to take a sample of several random graphs from the family, to gather information about what is "typical". Hence there is a need for algorithms which can generate graphs uniformly (or approximately uniformly) at random from the given family. Since a large sample may be required, the algorithm should also be computationally efficient. 
Rigorous analysis of such algorithms is often challenging, involving both combinatorial and probabilistic arguments. We will focus mainly on the set of all simple graphs with a particular degree sequence, and describe several different algorithms for sampling graphs from this family uniformly, or almost uniformly.
]]></description>
<dc:subject>review graph-theory random-graphs rather-interesting algorithms combinatorics sampling to-write-about to-visualize</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:10e6ca326168/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:review"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:random-graphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:sampling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1905.04490">
    <title>[1905.04490] Triangle-creation processes on cubic graphs</title>
    <dc:date>2022-03-12T13:04:45+00:00</dc:date>
    <link>https://arxiv.org/abs/1905.04490</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[An edge switch is an operation which makes a local change in a graph while maintaining the degree of every vertex. We introduce a switch move, called a triangle switch, which creates or deletes at least one triangle. Specifically, a make move is a triangle switch which chooses a path zwvxy of length 4 and replaces it by a triangle vxwv and an edge yz, while a break move performs the reverse operation. We consider various Markov chains which perform random triangle switches, and assume that every possible make or break move has positive probability of being performed. 
Our first result is that any such Markov chain is irreducible on the set of all 3-regular graphs with vertex set {1,2,…,n}. For a particular, natural Markov chain of this type, 
we obtain a non-trivial linear upper and lower bounds on the number of triangles in the long run. These bounds are almost surely obtained in linear time, irrespective of the starting graph.
]]></description>
<dc:subject>graph-theory rewriting-systems rather-interesting combinatorics random-graphs network-theory to-understand to-write-about to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:e077ff5346e5/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rewriting-systems"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:random-graphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:network-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1805.04991">
    <title>[1805.04991] Enumerating sparse uniform hypergraphs with given degree sequence and forbidden edges</title>
    <dc:date>2022-03-12T12:52:53+00:00</dc:date>
    <link>https://arxiv.org/abs/1805.04991</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[For n≥3 and r=r(n)≥3, let k=k(n)=(k1,…,kn) be a sequence of non-negative integers with sum M(k)=∑nj=1kj. We assume that M(k) is divisible by r for infinitely many values of n, and restrict our attention to these values. Let X=X(n) be a simple r-uniform hypergraph on the vertex set V={v1,v2,…,vn} with t edges and maximum degree xmax. We denote by r(k) the set of all simple r-uniform hypergraphs on the vertex set V with degree sequence k, and let r(k,X) be the set of all hypergraphs in r(k) which contain no edge of X. We give an asymptotic enumeration formula for the size of r(k,X). This formula holds when r4k3max=o(M(k)), tk3max=o(M(k)2) and rtk4max=o(M(k)3). Our proof involves the switching method. 
As a corollary, we obtain an asymptotic formula for the number of hypergraphs in r(k) which contain every edge of X. We apply this result to find asymptotic expressions for the expected number of perfect matchings and loose Hamilton cycles in a random hypergraph in r(k) in the regular case.
]]></description>
<dc:subject>hypergraphs enumeration combinatorics set-theory rather-interesting consider:these-trasitional-moves to-visualize consider:animation</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:603d26a848b7/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:hypergraphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:set-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:these-trasitional-moves"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:animation"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1805.07217">
    <title>[1805.07217] Tilings of the Sphere by Congruent Pentagons III: Edge Combination $a^5$</title>
    <dc:date>2022-03-12T12:48:49+00:00</dc:date>
    <link>https://arxiv.org/abs/1805.07217</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[There are exactly eight edge-to-edge tilings of the sphere by congruent equilateral pentagons: three pentagonal subdivision tilings with 12, 24, 60 tiles; four earth map tilings with 16, 20, 24, 24 tiles; and one flip modification of the earth map tiling with 20 tiles.
]]></description>
<dc:subject>tiling enumeration combinatorics spherical-geometry to-write-about to-visualize consider:interactive-app</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:580ea9c68e4a/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:tiling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:spherical-geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:interactive-app"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2002.02376">
    <title>[2002.02376] A Survey on String Constraint Solving</title>
    <dc:date>2022-03-11T11:31:01+00:00</dc:date>
    <link>https://arxiv.org/abs/2002.02376</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[String constraint solving refers to solving combinatorial problems involving constraints over string variables. String solving approaches have become popular over the last years given the massive use of strings in different application domains like formal analysis, automated testing, database query processing, and cybersecurity. This paper reports a comprehensive survey on string constraint solving by exploring the large number of approaches that have been proposed over the last decades to solve string constraints.
]]></description>
<dc:subject>constraint-satisfaction artificial-intelligence solvers rather-interesting combinatorics to-write-about to-embed consider:Wordle-and-so-on</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:36cef7daa153/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:artificial-intelligence"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:solvers"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-embed"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:Wordle-and-so-on"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1708.08975">
    <title>[1708.08975] On Rainbow Hamilton Cycles in Random Hypergraphs</title>
    <dc:date>2022-03-06T11:38:36+00:00</dc:date>
    <link>https://arxiv.org/abs/1708.08975</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Let H(k)n,p,r denote a randomly colored random hypergraph, constructed on the vertex set [n] by taking each k-tuple independently with probability p, and then independently coloring it with a random color from the set [r]. Let H be a k-uniform hypergraph of order n. An ℓ-Hamilton cycle is a spanning subhypergraph C of H with n/(k−ℓ) edges and such that for some cyclic ordering of the vertices each edge of C consists of k consecutive vertices and every pair of adjacent edges in C intersects in precisely ℓ vertices. 
In this note we study the existence of rainbow ℓ-Hamilton cycles (that is every edge receives a different color) in H(k)n,p,r. We mainly focus on the most restrictive case when r=n/(k−ℓ). In particular, we show that for the so called tight Hamilton cycles (ℓ=k−1) p=e2/n is the sharp threshold for the existence of a rainbow tight Hamilton cycle in H(k)n,p,n for each k≥4.]]></description>
<dc:subject>hypergraphs graph-coloring set-theory combinatorics proof rather-interesting to-write-about to-visualize consider:sampling</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:045f357f81c9/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:hypergraphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-coloring"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:set-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:proof"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:sampling"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2010.05666">
    <title>[2010.05666] The Erdos-Faber-Lovasz conjecture for weakly dense hypergraphs</title>
    <dc:date>2022-03-05T11:29:05+00:00</dc:date>
    <link>https://arxiv.org/abs/2010.05666</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Generalizing the concept of dense hypergraph, we say that a hypergraph is weakly dense, if no k in the half-open interval [2,sqrt(n)) is the degree of more than k^2 vertices. In our main result, we prove the famous Erdos-Faber-Lovasz conjecture when the hypergraph is weakly dense.
]]></description>
<dc:subject>hypergraphs combinatorics graph-coloring rather-interesting define-your-terms good-backgrounder to-write-about to-visualize consider:diagrams</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:503c8f92b48d/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:hypergraphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-coloring"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:define-your-terms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:good-backgrounder"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:diagrams"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1708.05223">
    <title>[1708.05223] The streaming $k$-mismatch problem</title>
    <dc:date>2022-02-28T14:03:37+00:00</dc:date>
    <link>https://arxiv.org/abs/1708.05223</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We consider the streaming complexity of a fundamental task in approximate pattern matching: the k-mismatch problem. It asks to compute Hamming distances between a pattern of length n and all length-n substrings of a text for which the Hamming distance does not exceed a given threshold k. In our problem formulation, we report not only the Hamming distance but also, on demand, the full \emph{mismatch information}, that is the list of mismatched pairs of symbols and their indices. The twin challenges of streaming pattern matching derive from the need both to achieve small working space and also to guarantee that every arriving input symbol is processed quickly. 
We present a streaming algorithm for the k-mismatch problem which uses O(klognlognk) bits of space and spends \ourcomplexity time on each symbol of the input stream, which consists of the pattern followed by the text. The running time almost matches the classic offline solution and the space usage is within a logarithmic factor of optimal. 
Our new algorithm therefore effectively resolves and also extends an open problem first posed in FOCS'09. En route to this solution, we also give a deterministic O(k(lognk+log|Σ|))-bit encoding of all the alignments with Hamming distance at most k of a length-n pattern within a text of length O(n). This secondary result provides an optimal solution to a natural communication complexity problem which may be of independent interest.
]]></description>
<dc:subject>information-theory signal-processing signal-to-noise combinatorics rather-interesting to-write-about to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:a8e32de4ab65/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:information-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:signal-processing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:signal-to-noise"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1909.12419">
    <title>[1909.12419] Counting Domineering Positions</title>
    <dc:date>2022-02-20T13:53:22+00:00</dc:date>
    <link>https://arxiv.org/abs/1909.12419</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Domineering is a two player game played on a checkerboard in which one player places dominoes vertically and the other places them horizontally. We give bivariate generating polynomials enumerating Domineering positions by the number of each player's pieces. We enumerate all positions, maximal positions, and positions where one player has no move. Using these polynomials we count the number of positions that occur during alternating play. Our method extends to enumerating positions from mid-game positions and we include an analysis of a tournament game.
]]></description>
<dc:subject>combinatorics mathematical-recreations enumeration rather-interesting representation board-games</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:7dc5953284b9/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:board-games"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2101.07608">
    <title>[2101.07608] Game values of arithmetic functions</title>
    <dc:date>2022-02-06T14:09:49+00:00</dc:date>
    <link>https://arxiv.org/abs/2101.07608</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Arithmetic functions in Number Theory meet the Sprague-Grundy function from Combinatorial Game Theory. We study a variety of 2-player games induced by standard arithmetic functions, such as Euclidian division, divisors, remainders and relatively prime numbers, and their negations.
]]></description>
<dc:subject>game-theory number-theory combinatorics partitions to-understand review meta-combinatorics rather-interesting</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:81e1157045d6/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:game-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:partitions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:review"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:meta-combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2103.15850">
    <title>[2103.15850] An upper bound on the size of Sidon sets</title>
    <dc:date>2022-01-31T13:43:41+00:00</dc:date>
    <link>https://arxiv.org/abs/2103.15850</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In this entry point into the subject, combining two elementary proofs, we decrease the gap between the upper and lower bounds by 0.2% in a classical combinatorial number theory problem. We show that the maximum size of a Sidon set of {1,2,…,n} is at most n‾√+0.998n1/4 for sufficiently large n.
]]></description>
<dc:subject>number-theory combinatorics rather-interesting proof mathematical-recreations to-write-about nudge-targets consider:classifying-a-set consider:feature-discovery</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:f907cc06ed49/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:proof"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:nudge-targets"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:classifying-a-set"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:feature-discovery"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2107.10318">
    <title>[2107.10318] MacMahon Partition Analysis: a discrete approach to broken stick problems</title>
    <dc:date>2022-01-29T12:31:50+00:00</dc:date>
    <link>https://arxiv.org/abs/2107.10318</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We propose a discrete approach to solve problems on forming polygons from broken sticks, which is akin to counting polygons with sides of integer length subject to certain Diophantine inequalities. Namely, we use MacMahon's Partition Analysis to obtain a generating function for the size of the set of segments of a broken stick subject to these inequalities. In particular, we use this approach to show that for n≥k≥3, the probability that a k-gon cannot be formed from a stick broken into n parts is given by n! over a product of linear combinations of partial sums of generalized Fibonacci numbers, a problem which proved to be very hard to generalize in the past.
]]></description>
<dc:subject>combinatorics probability-theory rather-interesting plane-geometry constraint-satisfaction number-theory all-kinds-of-stuff-really to-write-about to-understand OEIS</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:9999dc880227/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:probability-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:plane-geometry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:all-kinds-of-stuff-really"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:OEIS"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2010.11100">
    <title>[2010.11100] Extremal problems for pairs of triangles</title>
    <dc:date>2022-01-27T11:56:55+00:00</dc:date>
    <link>https://arxiv.org/abs/2010.11100</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[A convex geometric hypergraph or cgh consists of a family of subsets of a strictly convex set of points in the plane. There are eight pairwise nonisomorphic cgh's consisting of two disjoint triples. These were studied at length by Braß (2004) and by Aronov, Dujmović, Morin, Ooms, and da Silveira (2019). We determine the extremal functions exactly for seven of the eight configurations. 
The above results are about cyclically ordered hypergraphs. We extend some of them for triangle systems with vertices from a non-convex set. We also solve problems posed by P. Frankl, Holmsen and Kupavskii (2020), in particular, we determine the exact maximum size of an intersecting family of triangles whose vertices come from a set of n points in the plane.
]]></description>
<dc:subject>geometric-graphs hypergraphs combinatorics enumeration rather-interesting limited-cases to-write-about to-visualize consider:sampling consider:distributions consider:estimating</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:02fda276c259/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:geometric-graphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:hypergraphs"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:limited-cases"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:sampling"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:distributions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:estimating"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2109.14777">
    <title>[2109.14777] Use of primary decomposition of polynomial ideals arising from indicator functions to enumerate orthogonal fractions</title>
    <dc:date>2022-01-24T14:01:29+00:00</dc:date>
    <link>https://arxiv.org/abs/2109.14777</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[A polynomial indicator function of designs is first introduced by Fontana {\it et al}. (2000) for two-level cases. They give the structure of the indicator functions, especially the relation to the orthogonality of designs. These results are generalized by Aoki (2019) for general multi-level cases. As an application of these results, we can enumerate all orthogonal fractional factorial designs with given size and orthogonality using computational algebraic software. For example, Aoki (2019) gives classifications of orthogonal fractions of 2x2x2x2x3 designs with strength 3, which is derived by simple eliminations of variables. However, the computational feasibility of this naive approach depends on the size of the problems. In fact, it is reported that the computation of orthogonal fractions of 2x2x2x2x3 designs with strength 2 fails to carry out in Aoki (2019). In this paper, using the theory of primary decomposition, we enumerate and classify orthogonal fractions of 2x2x2x2x3 designs with strength 2. We show there are 35200 orthogonal half fractions of 2x2x2x2x3 designs with strength 2, classified into 63 equivalent classes.
]]></description>
<dc:subject>dimension-reduction experimental-design rather-interesting combinatorics algorithms polynomials enumeration to-write-about to-visualize consider:random-sampling</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:549f4020ab59/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:dimension-reduction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:experimental-design"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:polynomials"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:random-sampling"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1801.01288">
    <title>[1801.01288] There are 174 Subdivisions of the Hexahedron into Tetrahedra</title>
    <dc:date>2022-01-24T12:31:32+00:00</dc:date>
    <link>https://arxiv.org/abs/1801.01288</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[This article answers an important theoretical question: How many different subdivisions of the hexahedron into tetrahedra are there? It is well known that the cube has five subdivisions into 6 tetrahedra and one subdivision into 5 tetrahedra. However, all hexahedra are not cubes and moving the vertex positions increases the number of subdivisions. Recent hexahedral dominant meshing methods try to take these configurations into account for combining tetrahedra into hexahedra, but fail to enumerate them all: they use only a set of 10 subdivisions among the 174 we found in this article. 
The enumeration of these 174 subdivisions of the hexahedron into tetrahedra is our combinatorial result. Each of the 174 subdivisions has between 5 and 15 tetrahedra and is actually a class of 2 to 48 equivalent instances which are identical up to vertex relabeling. We further show that exactly 171 of these subdivisions have a geometrical realization, i.e. there exist coordinates of the eight hexahedron vertices in a three-dimensional space such that the geometrical tetrahedral mesh is valid. We exhibit the tetrahedral meshes for these configurations and show in particular subdivisions of hexahedra with 15 tetrahedra that have a strictly positive Jacobian.
]]></description>
<dc:subject>enumeration combinatorics probability-theory rather-interesting to-write-about to-simulate consider:visualization consider:sampling-methods</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:e443746bbcee/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:probability-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:sampling-methods"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1011.6195">
    <title>[1011.6195] The Enumeration of Prudent Polygons by Area and its Unusual Asymptotics</title>
    <dc:date>2022-01-23T12:32:36+00:00</dc:date>
    <link>https://arxiv.org/abs/1011.6195</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Prudent walks are special self-avoiding walks that never take a step towards an already occupied site, and \emph{k-sided prudent walks} (with k=1,2,3,4) are, in essence, only allowed to grow along k directions. Prudent polygons are prudent walks that return to a point adjacent to their starting point. Prudent walks and polygons have been previously enumerated by length and perimeter (Bousquet-Mélou, Schwerdtfeger; 2010). We consider the enumeration of \emph{prudent polygons} by \emph{area}. For the 3-sided variety, we find that the generating function is expressed in terms of a q-hypergeometric function, with an accumulation of poles towards the dominant singularity. This expression reveals an unusual asymptotic structure of the number of polygons of area n, where the critical exponent is the transcendental number log23 and and the amplitude involves tiny oscillations. Based on numerical data, we also expect similar phenomena to occur for 4-sided polygons. The asymptotic methodology involves an original combination of Mellin transform techniques and singularity analysis, which is of potential interest in a number of other asymptotic enumeration problems.
]]></description>
<dc:subject>combinatorics enumeration rather-interesting to-simulate to-write-about consider:visualization</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:b3d41e7abb1b/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:visualization"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1805.03863">
    <title>[1805.03863] Signature Catalan Combinatorics</title>
    <dc:date>2022-01-14T13:13:49+00:00</dc:date>
    <link>https://arxiv.org/abs/1805.03863</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The Catalan numbers constitute one of the most important sequences in combinatorics. Catalan objects have been generalized in various directions, including the classical Fuss-Catalan objects and the rational Catalan generalization of Armstrong-Rhoades-Williams. We propose a wider generalization of these families indexed by a composition s which is motivated by the combinatorics of planar rooted trees; when s=(2,...,2) and s=(k+1,...,k+1) we recover the classical Catalan and Fuss-Catalan combinatorics, respectively. Furthermore, to each pair (a,b) of relatively prime numbers we can associate a signature that recovers the combinatorics of rational Catalan objects. We present explicit bijections between the resulting s-Catalan objects, and a fundamental recurrence that generalizes the fundamental recurrence of the classical Catalan numbers. Our framework allows us to define signature generalizations of parking functions which coincide with the generalized parking functions studied by Pitman-Stanley and Yan, as well as generalizations of permutations which coincide with the notion of Stirling multipermutations introduced by Gessel-Stanley. Some of our constructions differ from the ones of Armstrong-Rhoades-Williams, however as a byproduct of our extension, we obtain the additional notions of rational permutations and rational trees.
]]></description>
<dc:subject>combinatorics enumeration rather-interesting review discrete-mathematics feature-construction to-write-about consider:equivalences consider:group-theory</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2c0d3c8e737c/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:review"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:discrete-mathematics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:feature-construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:equivalences"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:group-theory"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1906.06069">
    <title>[1906.06069] Combinatorial generation via permutation languages. I. Fundamentals</title>
    <dc:date>2022-01-02T21:24:09+00:00</dc:date>
    <link>https://arxiv.org/abs/1906.06069</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[In this work we present a general and versatile algorithmic framework for exhaustively generating a large variety of different combinatorial objects, based on encoding them as permutations. This approach provides a unified view on many known results and allows us to prove many new ones. In particular, we obtain four classical Gray codes for permutations, bitstrings, binary trees and set partitions as special cases. We present two distinct applications for our new framework: The first main application is the generation of pattern-avoiding permutations, yielding new Gray codes for different families of permutations that are characterized by the avoidance of certain classical patterns, (bi)vincular patterns, barred patterns, boxed patterns, Bruhat-restricted patterns, mesh patterns, monotone and geometric grid classes, and many others. We also obtain new Gray codes for all the combinatorial objects that are in bijection to these permutations, in particular for five different types of geometric rectangulations, also known as floorplans, which are divisions of a square into n rectangles subject to certain restrictions. The second main application of our framework are lattice congruences of the weak order on the symmetric group Sn. Recently, Pilaud and Santos realized all those lattice congruences as (n−1)-dimensional polytopes, called quotientopes, which generalize hypercubes, associahedra, permutahedra etc. Our algorithm generates the equivalence classes of each of those lattice congruences, by producing a Hamilton path on the skeleton of the corresponding quotientope, yielding a constructive proof that each of these highly symmetric graphs is Hamiltonian. We thus also obtain a provable notion of optimality for the Gray codes obtained from our framework: They translate into walks along the edges of a polytope.
]]></description>
<dc:subject>computational-methods combinatorics enumeration representation rather-interesting to-understand to-write-about consider:S-expressions consider:algebraic-simplification</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2e9ef103e118/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:computational-methods"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:S-expressions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:algebraic-simplification"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2105.11431">
    <title>[2105.11431] A lower bound for the $n$-queens problem</title>
    <dc:date>2022-01-01T13:52:09+00:00</dc:date>
    <link>https://arxiv.org/abs/2105.11431</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[The n-queens puzzle is to place n mutually non-attacking queens on an n×n chessboard. We present a simple two stage randomized algorithm to construct such configurations. In the first stage, a random greedy algorithm constructs an approximate \textit{toroidal} n-queens configuration. In this well-known variant the diagonals wrap around the board from left to right and from top to bottom. We show that with high probability this algorithm succeeds in placing (1−o(1))n queens on the board. In the second stage, the method of absorbers is used to obtain a complete solution to the non-toroidal problem. By counting the number of choices available at each step of the random greedy algorithm we conclude that there are more than ((1−o(1))ne−3)n solutions to the n-queens problem. This proves a conjecture of Rivin, Vardi, and Zimmerman in a strong form.
]]></description>
<dc:subject>combinatorics constraint-satisfaction mathematical-recreations proof to-write-about consider:guessing to-visualize</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:a8a2c3e3200b/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:proof"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:guessing"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1910.02662">
    <title>[1910.02662] On the existence of permutations conditioned by certain rational functions</title>
    <dc:date>2022-01-01T13:41:35+00:00</dc:date>
    <link>https://arxiv.org/abs/1910.02662</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We prove several conjectures made by Z.-W. Sun on the existence of permutations conditioned by certain rational functions. Furthermore, we fully characterize all integer values of the "inverse difference" rational function. Our proofs consist of both investigation of the mathematical properties of the rational functions and brute-force attack by computer for finding special permutations.
]]></description>
<dc:subject>combinatorics number-theory open-questions representation continued-fractions permutations to-understand to-write-about consider:looking-to-see</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:5794c86291aa/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:open-questions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:representation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:continued-fractions"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:looking-to-see"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2006.14070">
    <title>[2006.14070] Enumeration of Standard Puzzles</title>
    <dc:date>2022-01-01T13:36:39+00:00</dc:date>
    <link>https://arxiv.org/abs/2006.14070</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We introduce a large family of combinatorial objects, called standard puzzles, defined by very simple rules. We focus on the standard puzzles for which the enumeration problems can be solved by explicit formulas or by classical numbers, such as binomial coefficients, Fibonacci numbers, tangent numbers, Catalan numbers, ]]></description>
<dc:subject>combinatorics number-theory head-exploding-emoji to-understand to-write-about to-simulate consider:metaheuristics</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:f5d99cc2ff26/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:number-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:head-exploding-emoji"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:metaheuristics"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2109.14774">
    <title>[2109.14774] Fibonacci numbers, consecutive patterns, and inverse peaks</title>
    <dc:date>2021-12-19T12:45:52+00:00</dc:date>
    <link>https://arxiv.org/abs/2109.14774</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We give multiple proofs of two formulas concerning the enumeration of permutations avoiding a monotone consecutive pattern with a certain value for the inverse peak number or inverse left peak number statistic. The enumeration in both cases is given by a sequence related to Fibonacci numbers. We also show that there is exactly one permutation whose inverse peak number is zero among all permutations with any fixed descent composition, and we give a few elementary consequences of this fact. Our proofs involve generating functions, symmetric functions, regular expressions, and monomino-domino tilings.
]]></description>
<dc:subject>permutations patterns combinatorics rather-interesting to-understand feature-construction constraint-satisfaction</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:5bd999267590/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:permutations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:patterns"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:feature-construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:constraint-satisfaction"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2107.06188">
    <title>[2107.06188] The degree of asymmetry of sequences</title>
    <dc:date>2021-12-19T12:36:35+00:00</dc:date>
    <link>https://arxiv.org/abs/2107.06188</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We explore the notion of degree of asymmetry for integer sequences and related combinatorial objects. The degree of asymmetry is a new combinatorial statistic that measures how far an object is from being symmetric. We define this notion for compositions, words, matchings, binary trees and permutations, we find generating functions enumerating these objects with respect to their degree of asymmetry, and we describe the limiting distribution of this statistic in each case.
]]></description>
<dc:subject>symmetry combinatorics rather-interesting feature-construction group-theory strings to-understand to-write-about consider:code</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:497a7b1767d6/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:symmetry"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:feature-construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:group-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:strings"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-understand"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:code"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2106.01190">
    <title>[2106.01190] Counting Lyndon Subsequences</title>
    <dc:date>2021-11-16T10:27:29+00:00</dc:date>
    <link>https://arxiv.org/abs/2106.01190</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Counting substrings/subsequences that preserve some property (e.g., palindromes, squares) is an important mathematical interest in stringology. Recently, Glen et al. studied the number of Lyndon factors in a string. A string w=uv is called a Lyndon word if it is the lexicographically smallest among all of its conjugates vu. In this paper, we consider a more general problem "counting Lyndon subsequences". We show (1) the maximum total number of Lyndon subsequences in a string, (2) the expected total number of Lyndon subsequences in a string, (3) the expected number of distinct Lyndon subsequences in a string.
]]></description>
<dc:subject>strings combinatorics enumeration algorithms rather-interesting to-write-about consider:implementation consider:concentration</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:2e21349d14e5/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:strings"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:algorithms"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:implementation"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:concentration"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1704.00212">
    <title>[1704.00212] Three-dimensional Catalan numbers and product-coproduct prographs</title>
    <dc:date>2021-11-04T12:56:40+00:00</dc:date>
    <link>https://arxiv.org/abs/1704.00212</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[We present the new combinatorial class of product-coproduct prographs which are planar assemblies of two types of operators: products having two inputs and a single output and coproducts having a single input and two outputs. We show that such graphs are enumerated by the 3-dimensional Catalan numbers. We present some combinatorial bijections positioning product-coproduct prographs as key objects to probe families of objects enumerated by the 3-dimensional Catalan numbers.
]]></description>
<dc:subject>combinatorics graph-rewriting enumeration rather-interesting to-visualize to-simulate</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:8d23dbd0258b/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:graph-rewriting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/1701.08787">
    <title>[1701.08787] Vulnerability of Clustering under Node Failure in Complex Networks</title>
    <dc:date>2021-11-04T12:51:00+00:00</dc:date>
    <link>https://arxiv.org/abs/1701.08787</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[Robustness in response to unexpected events is always desirable for real-world networks. To improve the robustness of any networked system, it is important to analyze vulnerability to external perturbation such as random failures or adversarial attacks occurring to elements of the network. In this paper, we study an emerging problem in assessing the robustness of complex networks: the vulnerability of the clustering of the network to the failure of network elements. Specifically, we identify vertices whose failures will critically damage the network by degrading its clustering, evaluated through the average clustering coefficient. This problem is important because any significant change made to the clustering, resulting from element-wise failures, could degrade network performance such as the ability for information to propagate in a social network. We formulate this vulnerability analysis as an optimization problem, prove its NP-completeness and non-monotonicity, and we offer two algorithms to identify the vertices most important to clustering. Finally, we conduct comprehensive experiments in synthesized social networks generated by various well-known models as well as traces of real social networks. The empirical results over other competitive strategies show the efficacy of our proposed algorithms.
]]></description>
<dc:subject>network-theory robustness security combinatorics feature-construction to-simulate to-write-about</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:6d8a6eb2d889/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:network-theory"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:robustness"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:security"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:feature-construction"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-simulate"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
</rdf:Bag></taxo:topics>
</item>
<item rdf:about="https://arxiv.org/abs/2107.10167">
    <title>[2107.10167] Enumeration of Polyominoes &amp; Polycubes Composed of Magnetic Cubes</title>
    <dc:date>2021-10-30T01:19:54+00:00</dc:date>
    <link>https://arxiv.org/abs/2107.10167</link>
    <dc:creator>Vaguery</dc:creator><description><![CDATA[This paper examines a family of designs for magnetic cubes and counts how many configurations are possible for each design as a function of the number of modules. 
Magnetic modular cubes are cubes with magnets arranged on their faces. The magnets are positioned so that each face has either magnetic south or north pole outward. Moreover, we require that the net magnetic moment of the cube passes through the center of opposing faces. These magnetic arrangements enable coupling when cube faces with opposite polarity are brought in close proximity and enable moving the cubes by controlling the orientation of a global magnetic field. This paper investigates the 2D and 3D shapes that can be constructed by magnetic modular cubes, and describes all possible magnet arrangements that obey these rules. We select ten magnetic arrangements and assign a "colo"' to each of them for ease of visualization and reference. We provide a method to enumerate the number of unique polyominoes and polycubes that can be constructed from a given set of colored cubes. We use this method to enumerate all arrangements for up to 20 modules in 2D and 16 modules in 3D. We provide a motion planner for 2D assembly and through simulations compare which arrangements require fewer movements to generate and which arrangements are more common. Hardware demonstrations explore the self-assembly and disassembly of these modules in 2D and 3D.
]]></description>
<dc:subject>combinatorics self-assembly rather-interesting rather-odd magnets mathematical-recreations enumeration to-write-about to-visualize consider:forbidden-patterns consider:rarity</dc:subject>
<dc:source>https://pinboard.in/</dc:source>
<dc:identifier>https://pinboard.in/u:Vaguery/b:41dab87f2b12/</dc:identifier>
<taxo:topics><rdf:Bag>	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:combinatorics"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:self-assembly"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-interesting"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:rather-odd"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:magnets"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:mathematical-recreations"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:enumeration"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-write-about"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:to-visualize"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:forbidden-patterns"/>
	<rdf:li rdf:resource="https://pinboard.in/u:Vaguery/t:consider:rarity"/>
</rdf:Bag></taxo:topics>
</item>
</rdf:RDF>