bluuebunny/crossref_metadata_2025_split huggingface dataset:
Random Numerical Semigroups and a Simplicial Complex of Irreducible Semigroups
Authors: De Loera Jesus , O'Neill Christopher , Wilburne Dane 
Published: January 2020

We examine properties of random numerical semigroups under a probabilistic model inspired by the Erdos-Renyi model for random graphs. We provide a threshold function for cofiniteness, and bound the expected embedding dimension, genus, and Frobenius number of random semigroups. Our results follow, surprisingly, from the construction of a very natural shellable simplicial complex whose facets are in bijection with irreducible numerical semigroups of a fixed Frobenius number and whose $h$-vector determines the probability that a particular element lies in the semigroup.
Minimal Multiple Blocking Sets
Authors: Bishnoi Anurag , Mattheus Sam , Schillewaert Jeroen 
Published: January 2020

We prove that a minimal $t$-fold blocking set in a finite projective plane of order $n$ has cardinality at most \[\frac{1}{2} n\sqrt{4tn - (3t + 1)(t - 1)} + \frac{1}{2} (t - 1)n + t.\] This is the first general upper bound on the size of minimal $t$-fold blocking sets in finite projective planes and it generalizes the classical result of Bruen and Thas on minimal blocking sets. From the proof it directly follows that if equality occurs in this bound then every line intersects the blocking set $S$ in either $t$ points or $\frac{1}{2}(\sqrt{4tn - (3t + 1)(t - 1)} + t - 1) + 1$ points. We use this to show that for $n$ a prime power, equality can occur in our bound in exactly one of the following three cases: (a) $t = 1$, $n$ is a square and $S$ is a unital; (b) $t = n - \sqrt{n}$, $n$ is a square and $S$ is the complement of a Baer subplane; (c) $t = n$ and $S$ is equal to the set of all points except one. For a square prime power $q$ and $t \leq \sqrt{q} + 1$, we give a construction of a minimal $t$-fold blocking set $S$ in $\mathrm{PG}(2,q)$ with $|S| = q\sqrt{q} + 1 + (t - 1)(q - \sqrt{q} + 1)$. Furthermore, we obtain an upper bound on the size of minimal blocking sets in symmetric $2$-designs and use it to give new proofs of other known results regarding tangency sets in higher dimensional finite projective spaces. We also discuss further generalizations of our bound. In our proofs we use an incidence bound on combinatorial designs which follows from applying the expander mixing lemma to the incidence graph of these designs.
On the Rainbow Turán number of paths
Authors: Ergemlidze Beka , Győri Ervin , Methuku Abhishek 
Published: January 2020

Let $F$ be a fixed graph. The rainbow Turán number of $F$ is defined as the maximum number of edges in a graph on $n$ vertices that has a proper edge-coloring with no rainbow copy of $F$ (i.e., a copy of $F$ all of whose edges have different colours). The systematic study of such problems was initiated by Keevash, Mubayi, Sudakov and Verstraëte.
In this paper, we show that the rainbow Turán number of a path with $k+1$ edges is less than $\left(9k/7+2\right) n$, improving an earlier estimate of Johnston, Palmer and Sarkar.
Structure of Cubic Lehman Matrices
Authors: Mayhew Dillon , Pivotto Irene , Royle Gordon 
Published: January 2020

A pair $(A,B)$ of square $(0,1)$-matrices is called a Lehman pair if $AB^T=J+kI$ for some integer $k\in\{-1,1,2,3,\ldots\}$. In this case $A$ and $B$ are called Lehman matrices. This terminology arises because Lehman showed that the rows with the fewest ones in any non-degenerate minimally nonideal (mni) matrix $M$ form a square Lehman submatrix of $M$. Lehman matrices with $k=-1$ are essentially equivalent to partitionable graphs (also known as $(\alpha,\omega)$-graphs), so have been heavily studied as part of attempts to directly classify minimal imperfect graphs. In this paper, we view a Lehman matrix as the bipartite adjacency matrix of a regular bipartite graph, focusing in particular on the case where the graph is cubic. From this perspective, we identify two constructions that generate cubic Lehman graphs from smaller Lehman graphs. The most prolific of these constructions involves repeatedly replacing suitable pairs of edges with a particular $6$-vertex subgraph that we call a $3$-rung ladder segment. Two decades ago, Lütolf & Margot initiated a computational study of mni matrices and constructed a catalogue containing (among other things) a listing of all cubic Lehman matrices with $k =1$ of order up to $17 \times 17$. We verify their catalogue (which has just one omission), and extend the computational results to $20 \times 20$ matrices. Of the $908$ cubic Lehman matrices (with $k=1$) of order up to $20 \times 20$, only two do not arise from our $3$-rung ladder construction. However these exceptions can be derived from our second construction, and so our two constructions cover all known cubic Lehman matrices with $k=1$.
Combining Extensions of the Hales-Jewett Theorem with Ramsey Theory in Other Structures
Authors: Hindman Neil , Strauss Dona , Zamboni Luca Q. 
Published: January 2020

The Hales-Jewett Theorem states that given any finite nonempty set ${\mathbb A}$ and any finite coloring of the free semigroup $S$ over the alphabet ${\mathbb A}$ there is a variable word over ${\mathbb A}$ all of whose instances are the same color. This theorem has some extensions involving several distinct variables occurring in the variable word. We show that, when combined with a sufficiently well behaved homomorphism, the relevant variable word simultaneously satisfies a Ramsey-Theoretic conclusion in the other structure. As an example we show that if $\tau$ is the homomorphism from the set of variable words into the natural numbers which associates to each variable word $w$ the number of occurrences of the variable in $w$, then given any finite coloring of $S$ and any infinite sequence of natural numbers, there is a variable word $w$ whose instances are monochromatic and $\tau(w)$ is a sum of distinct members of the given sequence.Our methods rely on the algebraic structure of the Stone-Čech compactification of $S$ and the other semigroups that we consider. We show for example that if $\tau$ is as in the paragraph above, there is a compact subsemigroup $P$ of $\beta{\mathbb N}$ which contains all of the idempotents of $\beta{\mathbb N}$ such that, given any $p\in P$, any $A\in p$, and any finite coloring of $S$, there is a variable word $w$ whose instances are monochromatic and $\tau(w)\in A$.We end with a new short algebraic proof of an infinitary extension of the Graham-Rothschild Parameter Sets Theorem.
Circular Repetition Thresholds on Some Small Alphabets: Last Cases of Gorbunova's Conjecture
Authors: Currie James D. , Mol Lucas , Rampersad Narad 
Published: January 2020

A word is called $\beta$-free if it has no factors of exponent greater than or equal to $\beta$. The repetition threshold $\mbox{RT}(k)$ is the infimum of the set of all $\beta$ such that there are arbitrarily long $k$-ary $\beta$-free words (or equivalently, there are $k$-ary $\beta$-free words of every sufficiently large length, or even every length). These three equivalent definitions of the repetition threshold give rise to three natural definitions of a repetition threshold for circular words. The infimum of the set of all $\beta$ such that

there are arbitrarily long $k$-ary $\beta$-free circular words is called the weak circular repetition threshold, denoted $\mbox{CRT}_\mbox{W}(k)$;
there are $k$-ary $\beta$-free circular words of every sufficiently large length is called the intermediate circular repetition threshold, denoted $\mbox{CRT}_\mbox{I}(k)$;
there are $k$-ary $\beta$-free circular words of every length is called the strong circular repetition threshold, denoted $\mbox{CRT}_\mbox{S}(k)$.

We prove that $\mbox{CRT}_\mbox{S}(4)=\tfrac{3}{2}$ and $\mbox{CRT}_\mbox{S}(5)=\tfrac{4}{3}$, confirming a conjecture of Gorbunova and providing the last unknown values of the strong circular repetition threshold. We also prove that $\mbox{CRT}_\mbox{S}(3)=\mbox{CRT}_\mbox{W}(3)=\mbox{RT}(3)=\tfrac{7}{4}$.
$(k,\lambda)$-Anti-Powers and Other Patterns in Words
Authors: Burcroff Amanda 
Published: January 2020

Given a word, we are interested in the structure of its contiguous subwords split into $k$ blocks of equal length, especially in the homogeneous and anti-homogeneous cases. We introduce the notion of $(\mu_1,\dots,\mu_k)$-block-patterns, words of the form $w = w_1\cdots w_k$ where, when $\{w_1,\dots,w_k\}$ is partitioned via equality, there are $\mu_s$ sets of size $s$ for each $s \in \{1,\dots,k\}$. This is a generalization of the well-studied $k$-powers and the $k$-anti-powers recently introduced by Fici, Restivo, Silva, and Zamboni, as well as a refinement of the $(k,\lambda)$-anti-powers introduced by Defant. We generalize the anti-Ramsey-type results of Fici et al. to $(\mu_1,\dots,\mu_k)$-block-patterns and improve their bounds on $N_\alpha(k,k)$, the minimum length such that every word of length $N_\alpha(k,k)$ on an alphabet of size $\alpha$ contains a $k$-power or $k$-anti-power. We also generalize their results on infinite words avoiding $k$-anti-powers to the case of $(k,\lambda)$-anti-powers. We provide a few results on the relation between $\alpha$ and $N_\alpha(k,k)$ and find the expected number of $(\mu_1,\dots,\mu_k)$-block-patterns in a word of length $n$.
Axioms for Shifted Tableau Crystals
Authors: Gillespie Maria , Levinson Jake 
Published: January 2020

We give local axioms that uniquely characterize the crystal-like structure on shifted tableaux developed by the authors and Purbhoo. These axioms closely resemble those developed by Stembridge for type A tableau crystals. This axiomatic characterization gives rise to a new method for proving and understanding Schur $Q$-positive expansions in symmetric function theory, just as the Stembridge axiomatic structure provides for ordinary Schur positivity.
Rainbow Matchings in Properly-Colored Hypergraphs
Authors: Huang Hao , Li Tong , Wang Guanghui 
Published: January 2020

A hypergraph $H$ is properly colored if for every vertex $v\in V(H)$, all the edges incident to $v$ have distinct colors. In this paper, we show that if $H_{1}, \ldots, H_{s}$ are properly-colored $k$-uniform hypergraphs on $n$ vertices, where $n\geq3k^{2}s$, and $e(H_{i})>{{n}\choose {k}}-{{n-s+1}\choose {k}}$, then there exists a rainbow matching of size $s$, containing one edge from each $H_i$. This generalizes some previous results on the Erdős Matching Conjecture.
Extremal $H$-Free Planar Graphs
Authors: Lan Yongxin , Shi Yongtang , Song Zi-Xia 
Published: January 2020

Given a graph $H$, a graph is $H$-free if it does not contain $H$ as a subgraph. We continue to study the topic of "extremal" planar graphs initiated by Dowden [J. Graph Theory 83 (2016) 213–230], that is, how many edges can an $H$-free planar graph on $n$ vertices have? We define $ex_{_\mathcal{P}}(n,H)$ to be the maximum number of edges in an $H$-free planar graph on $n $ vertices. We first obtain several sufficient conditions on $H$ which yield $ex_{_\mathcal{P}}(n,H)=3n-6$ for all $n\ge |V(H)|$. We discover that the chromatic number of $H$ does not play a role, as in the celebrated Erdős-Stone Theorem. We then completely determine $ex_{_\mathcal{P}}(n,H)$ when $H$ is a wheel or a star. Finally, we examine the case when $H$ is a $(t, r)$-fan, that is, $H$ is isomorphic to $K_1+tK_{r-1}$, where $t\ge2$ and $r\ge 3$ are integers. However, determining $ex_{_\mathcal{P}}(n,H)$, when $H$ is a planar subcubic graph, remains wide open.
VC Dimension and a Union Theorem for Set Systems
Authors: Cambie Stijn , Girão António , Kang Ross J. 
Published: January 2020

Fix positive integers $k$ and $d$. We show that, as $n\to\infty$, any set system $\mathcal{A} \subset 2^{[n]}$ for which the VC dimension of $\{ \triangle_{i=1}^k S_i \mid S_i \in \mathcal{A}\}$ is at most $d$ has size at most $(2^{d\bmod{k}}+o(1))\binom{n}{\lfloor d/k\rfloor}$. Here $\triangle$ denotes the symmetric difference operator. This is a $k$-fold generalisation of a result of Dvir and Moran, and it settles one of their questions.
A key insight is that, by a compression method, the problem is equivalent to an extremal set theoretic problem on $k$-wise intersection or union that was originally due to Erdős and Frankl.
We also give an example of a family $\mathcal{A} \subset 2^{[n]}$ such that the VC dimension of $\mathcal{A}\cap \mathcal{A}$ and of $\mathcal{A}\cup \mathcal{A}$ are both at most $d$, while $\lvert \mathcal{A} \rvert = \Omega(n^d)$. This provides a negative answer to another question of Dvir and Moran.
On the Weight of Berge-$F$-Free Hypergraphs
Authors: English Sean , Gerbner Dániel , Methuku Abhishek , Palmer Cory 
Published: January 2020

For a graph $F$, we say a hypergraph is a Berge-$F$ if it can be obtained from $F$ by replacing each edge of $F$ with a hyperedge containing it. A hypergraph is Berge-$F$-free if it does not contain a subhypergraph that is a Berge-$F$. The weight of a non-uniform hypergraph $\mathcal{H}$ is the quantity $\sum_{h \in E(\mathcal{H})} |h|$.
Suppose $\mathcal{H}$ is a Berge-$F$-free hypergraph on $n$ vertices. In this short note, we prove that as long as every edge of $\mathcal{H}$ has size at least the Ramsey number of $F$, the weight of $\mathcal{H}$ is $o(n^2)$. This result is best possible in some sense. Along the way, we study other weight functions, and strengthen results of Gerbner and Palmer; and Grósz, Methuku and Tompkins.
A New Bijection Between RNA Secondary Structures and Plane Trees and its Consequences
Authors: Chen Ricky Xiaofeng 
Published: January 2020

In this paper, we first present a new bijection between RNA secondary structures and plane trees. Combined with the Schmitt-Waterman bijection between these objects, we then obtain a bijection on plane trees that relates the horizontal fiber decomposition associated to internal vertices to the degrees of odd-level vertices while the vertical path decomposition associated to leaves is related to the degrees of even-level vertices. To the best of our knowledge, only the former relation (i.e., horizontal vs odd-level) due to Deutsch is known. As a consequence, we obtain enumeration results for various classes of plane trees, e.g., refining the Narayana numbers and the enumeration involving young leaves due to Chen, Deutsch and Elizalde, and counting a newly introduced `vertical' version of $k$-ary trees. The enumeration results can be also formulated in terms of RNA secondary structures with certain parameterized features, which might have some biological significance.
Distribution of Variables in Lambda-Terms with Restrictions on De Bruijn Indices and De Bruijn Levels
Authors: Gittenberger Bernhard , Larcher Isabella 
Published: January 2020

We consider two special subclasses of lambda-terms that are restricted by a bound on the number of abstractions between a variable and its binding lambda, the so-called De-Bruijn index, or by a bound on the nesting levels of abstractions, i.e., the number of De Bruijn levels, respectively.
We show that the total number of variables is asymptotically normally distributed for both subclasses of lambda-terms with mean and variance asymptotically equal to $Cn$ and $\tilde{C}n$, respectively, where the constants $C$ and $\tilde{C}$ depend on the bound that has been imposed. For the class of lambda-terms with bounded De Bruijn index we derive closed formulas for the constant. For the other class of lambda-terms that we consider, namely lambda-terms with a bounded number of De Bruijn levels, we show quantitative and distributional results on the number of variables, as well as abstractions and applications, in the different De Bruijn levels and thereby exhibit a so-called "unary profile" that attains a very interesting shape.
Our results give a combinatorial explanation of an earlier discovered strange phenomenon exhibited by the counting sequence of this particular class of lambda-terms.
Kementerian Pertahanan: Birokrasi Sipil atau Hierarki Militer
Authors: Djuyandi Yusa , Ghazian Muhammad Gufran 
Published: January 2020

Militer dan kementerian pertahanan merupakan dua unsur yang tidak dapat dipisahkan. Hal ini dapat dianalisa dari dua sudut pandang. Pertama, fungsi dari masing-masing institusi yang saling terkait. Kedua, keberadaan tokoh-tokoh militer di tubuh kementerian pertahanan. Distribusi kendali atas masyarakat sipil akan menjadi baik apabila undang-undang sesuai dengan kebutuhan negara dan implementasinya sesuai dengan undang undang yang telah disinkronisasi dengan hajat negara. Permasalahan distribusi kontrol masyarakat sipil di tubuh kementerian pertahanan dapat dilihat pada dua tahap pembuatan kebijakan, Dua hal tersebut adalah perumusan dan implementasi, sehingga kebijakan publik ini membutuhkan evaluasi karena dampaknya yang begitu luas terhadap kontrol masyarakat sipil dan permasalahan pada dua tahap di atas.
A Catalog of Emission-line Galaxies from the Faint Infrared Grism Survey: Studying Environmental Influence on Star Formation
Authors: Pharo John , Malhotra Sangeeta , Rhoads James E. , Pirzkal Norbert , Finkelstein Steven L. , Ryan Russell , Cimatti Andrea , Christensen Lise , Hathi Nimish , Koekemoer Anton , Harish Santosh , Smith Mark , Straughn Amber , Windhorst Rogier , Ferreras Ignacio , Gronwall Caryl , Hibon Pascale , Larson Rebecca , O’Connell Robert , Pasquali Anna , Tilvi Vithal 
Published: January 2020

Abstract
We present a catalog of 208 0.3 < z < 2.1 emission-line galaxies (ELGs) selected from 1D slitless spectroscopy obtained using Hubble’s WFC3 G102 grism, as part of the Faint Infrared Grism Survey. We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission-line fluxes and errors, redshifts, and equivalent widths for Hα λ6563, [O iii] λλ4959, 5007, and [O ii] λ3727 emission lines, for ELGs down to AB(F105W) >28 and >10−17 erg cm−2 s−1 line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy’s environment. We use seventh-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [O iii] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SFR) versus stellar mass and find no significant influence of environment on that relation. We calculate SFRs and find no dependence of SFR on local galaxy surface density for 0.3 < z < 0.8 Hα emitters and for 0.8 < z < 1.3 [O iii] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities Σ ≤ 30 Mpc−2, we find no consistent effect of environment on star formation.
D’une marginalité à l’autre : droit à la ville et pratiques de réadaptation des « bidonvillois » dans les nouvelles marges urbaines de Rabat
Authors: Harroud Tarik 
Published: January 2020

La contribution porte sur le vécu et les pratiques de revendication du droit à la ville par des populations « bidonvilloises » relogées dans les grandes opérations de résorption en périphérie de Rabat. Elle examine plus particulièrement la manière par laquelle se construisent les légitimités ordinaires dans ces immenses opérations résidentielles peu équipées et situées physiquement et symboliquement « hors de la ville », incarnant une nouvelle « marginalité » pour ces populations défavorisées. Au-delà des mobilisations sociales de contestation qui expriment leurs revendications à un logement digne ou au droit à la ville (transport, équipements, sécurité, emploi, etc.), ce sont surtout leurs pratiques quotidiennes de réadaptation, que nous cherchons à analyser et explorer en faisant ressortir les différentes stratégies qu’elles mobilisent (solidarités sociales en matière de gestion des quartiers et d’entretien des espaces publics, de création d’équipements de base, des stratégies de déplacement vers la ville-centre, le recours à l’informel, etc.) afin de s’adapter à ce nouveau contexte spécifique. Sur la base d’une série d’observations et d’entretiens réalisés avec un échantillon exploratoire de populations qui ont été transférées de la capitale et ses territoires limitrophes vers deux grandes opérations de résorption situées dans ses périphéries urbaines (ville nouvelle de Tamesna et le centre périurbain d’Ain Aouda), nous envisageons d’étudier la manière avec laquelle se construit et se justifie le droit à la ville dans ces espaces périphériques ainsi que les formes de réactivation ou de réinvention des pratiques de résistance auparavant à l’œuvre dans leurs bidonvilles.
Femmes et propriété seigneuriale au Canada (XVII e -XIX e siècles) : les formes de l’autorité des « seigneuresses »
Authors: Grenier Benoît 
Published: January 2020

Dans la société canadienne préindustrielle, la seigneurie constitue une composante fondamentale et caractérise les relations sociales ainsi que les modes d’accession à la terre. Au cours des deux siècles et demi pendant lesquels s’est officiellement maintenu le régime, les femmes ont joué un rôle significatif au sein de cette institution en détenant fréquemment l’autorité seigneuriale. Ces « seigneuresses », comme on les désigne dans les sources, sont toutefois rarement les égales des seigneurs et leur pouvoir est étroitement encadré par le droit et les conventions sociales. L’article s’intéresse aux formes et aux modalités de cette autorité seigneuriale féminine, qu’il s’agisse des religieuses-seigneuresses, des femmes concessionnaires de fiefs ou encore des héritières sans frère. Il vise à définir les formes et les limites de ce pouvoir féminin en croisant histoire du genre et histoire seigneuriale.
Vendre aux héritiers : circulation et immobilisation de l’office de payeur des rentes au XVIII e siècle
Authors: Marraud Mathieu 
Published: January 2020

La circulation marchande de l’office, au xviii e siècle, n’induit pas forcément l’existence d’un marché entre vendeurs et acquéreurs. La cession d’un office comme celui de payeur des rentes de l’Hôtel de Ville de Paris, l’un des plus coûteux de l’époque, s’appuie sur des exigences prenant sens, d’une part, dans de larges pratiques de transmission familiale, et, d’autre part, dans un univers de notabilité socialement fermé. Les familles négociantes qui l’ont investi, depuis la Régence, y ont transféré leurs crédits personnels au service du crédit monarchique : le versement des arrérages de rentes sur l’État auprès des porteurs. Ainsi la vente de ces offices dessine les contours d’un espace politique et économique, bourgeois, habité de fronts de parenté qui se perpétuent à travers elle.
Le technological gatekeeper « chef d’orchestre » de l’ambidextrie organisationnelle
Authors: Saibi Mohand Amokrane , Naji Fairouz 
Published: January 2020

Nombreuses sont les recherches mettant en évidence le rôle prépondérant des technological gatekeepers (TG) dans la collecte et l’intégration des connaissances externes à des fins d’innovation. Toutefois, à notre connaissance, aucune n’examine de façon précise le rôle qu’ils pourraient jouer dans la conciliation des innovations d’exploitation et d’exploration. Pour faire face à cette lacune, nous nous appuyons sur une étude de cas portant sur une entreprise innovante afin d’appréhender l’importance des rôles assumés par cet agent relationnel de l’innovation, et la façon dont ils peuvent se décliner dans l’articulation de ces deux logiques d’innovation. Il s’agit donc d’identifier le rôle du TG dans la combinaison de ces dernières et de mieux comprendre les mécanismes en jeu pour atteindre l’ambidextrie organisationnelle. Notre recherche montre que cet acteur occupe une place centrale contribuant à fluidifier la circulation des connaissances entre les unités d’exploration et d’exploitation afin de mieux les articuler. Codes JEL : O31, O32