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https://arxiv.org/abs/1602.07209
Polytopes and simplexes in p-adic fields
We introduce topological notions of polytopes and simplexes, the latter being expected to play in p-adically closed fields the role played by real simplexes in the classical results of triangulation of semi-algebraic sets over real closed fields. We prove that the faces of every p-adic polytope are polytopes and that t...
\section{Introduction} \label{se:intro} Throughout all this paper we fix a $p$\--adically closed field $(K,v)$. The reader unfamiliar with this notion may restrict to the special case where $K={\rm\bf Q}_p$ or a finite extension of it, and $v$ is its $p$\--adic valuation. We let $R$ denote the valuation ring of $v$,...
{ "timestamp": "2016-11-15T02:12:28", "yymm": "1602", "arxiv_id": "1602.07209", "language": "en", "url": "https://arxiv.org/abs/1602.07209", "abstract": "We introduce topological notions of polytopes and simplexes, the latter being expected to play in p-adically closed fields the role played by real simplex...
https://arxiv.org/abs/1202.1218
A geometrical triumvirate of real random matrices
We present a five-step method for the calculation of eigenvalue correlation functions for various ensembles of real random matrices, based upon the method of (skew-) orthogonal polynomials. This scheme systematises existing methods and also involves some new techniques. The ensembles considered are: the Gaussian Orthog...
\section*{} \pagenumbering{roman} \thispagestyle{empty} \begin{centering} \vspace{60pt}A GEOMETRICAL TRIUMVIRATE OF REAL RANDOM MATRICES \vspace{12pt} Anthony Mays \vspace{280pt}Submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy \vspace{50pt}November 2011 \vspace{12pt}Departmen...
{ "timestamp": "2012-02-07T02:03:50", "yymm": "1202", "arxiv_id": "1202.1218", "language": "en", "url": "https://arxiv.org/abs/1202.1218", "abstract": "We present a five-step method for the calculation of eigenvalue correlation functions for various ensembles of real random matrices, based upon the method o...
https://arxiv.org/abs/1611.07820
Local variational study of 2d lattice energies and application to Lennard-Jones type interactions
In this paper, we focus on finite Bravais lattice energies per point in two dimensions. We compute the first and second derivatives of these energies. We prove that the Hessian at the square and the triangular lattice are diagonal and we give simple sufficient conditions for the local minimality of these lattices. Furt...
\section{Introduction} \subsection{Minimization at high and low densities: our previous works} In our previous work with Zhang \cite{Betermin:2014fy}, generalized in \cite{BetTheta15}, we studied some two-dimensional lattice energies among Bravais lattices. More precisely, these energies are defined, for any Bravais l...
{ "timestamp": "2016-11-24T02:06:38", "yymm": "1611", "arxiv_id": "1611.07820", "language": "en", "url": "https://arxiv.org/abs/1611.07820", "abstract": "In this paper, we focus on finite Bravais lattice energies per point in two dimensions. We compute the first and second derivatives of these energies. We ...
https://arxiv.org/abs/2206.01544
Polynomial approximation on $C^2$-domains
We introduce appropriate computable moduli of smoothness to characterize the rate of best approximation by multivariate polynomials on a connected and compact $C^2$-domain $\Omega\subset \mathbb{R}^d$. This new modulus of smoothness is defined via finite differences along the directions of coordinate axes, and along a ...
\subsection{Decomposition of the domain in $\RR^d$} \subjclass[2010]{Primary 41A10, 41A17, 41A27, 41A63;\\Secondary 41A55, 65D32} \keywords{$C^2$-domains, polynomial approximation, modulus of smoothness, Jackson inequality, inverse theorem} \begin{abstract} We introduce appropriate computable moduli of smoot...
{ "timestamp": "2022-06-06T02:13:14", "yymm": "2206", "arxiv_id": "2206.01544", "language": "en", "url": "https://arxiv.org/abs/2206.01544", "abstract": "We introduce appropriate computable moduli of smoothness to characterize the rate of best approximation by multivariate polynomials on a connected and com...
https://arxiv.org/abs/0906.3132
Constructing matrix geometric means
In this paper, we analyze the process of "assembling" new matrix geometric means from existing ones, through function composition or limit processes. We show that for n=4 a new matrix mean exists which is simpler to compute than the existing ones. Moreover, we show that for n>4 the existing proving strategies cannot pr...
\section{Introduction} \paragraph{Literature review} In the last few years, several papers have been devoted to defining a proper way to generalize the concept of geometric mean to $n \geq 3$ Hermitian, positive definite $m \times m$ matrices. A seminal paper by Ando, Li and Mathias \cite{alm} defined the mathematical ...
{ "timestamp": "2010-07-27T02:01:03", "yymm": "0906", "arxiv_id": "0906.3132", "language": "en", "url": "https://arxiv.org/abs/0906.3132", "abstract": "In this paper, we analyze the process of \"assembling\" new matrix geometric means from existing ones, through function composition or limit processes. We s...
https://arxiv.org/abs/1207.5015
Free and Very Free Morphisms into a Fermat Hypersurface
This paper studies the existence of free and very free curves on the degree 5 Fermat hypersurface in P^5 over a field of characteristic 2. We find that such curves exist in degrees 8 and 9 and not in lower degrees.
\section{Introduction} \noindent Any smooth projective Fano variety in characteristic zero is rationally connected and hence contains a very free rational curve. In positive characteristic a smooth projective Fano variety is rationally chain connected. However, it is not known whether such varieties are separably rati...
{ "timestamp": "2012-07-26T02:06:22", "yymm": "1207", "arxiv_id": "1207.5015", "language": "en", "url": "https://arxiv.org/abs/1207.5015", "abstract": "This paper studies the existence of free and very free curves on the degree 5 Fermat hypersurface in P^5 over a field of characteristic 2. We find that such...
https://arxiv.org/abs/1001.3885
Improved Source Coding Exponents via Witsenhausen's Rate
We provide a novel upper-bound on Witsenhausen's rate, the rate required in the zero-error analogue of the Slepian-Wolf problem; our bound is given in terms of a new information-theoretic functional defined on a certain graph. We then use the functional to give a single letter lower-bound on the error exponent for the ...
\section{Introduction} Under consideration is the communication problem depicted in Figure \ref{fig:scsi}; nature produces a sequence $(X_i,Y_i)$ governed by the i.i.d. distribution $P_{XY}$ on alphabet $\mathcal{X} \times \mathcal{Y}$. An encoder, observing the sequence $X^n$, must send a message to a decoder, obse...
{ "timestamp": "2010-01-21T22:30:48", "yymm": "1001", "arxiv_id": "1001.3885", "language": "en", "url": "https://arxiv.org/abs/1001.3885", "abstract": "We provide a novel upper-bound on Witsenhausen's rate, the rate required in the zero-error analogue of the Slepian-Wolf problem; our bound is given in terms...
https://arxiv.org/abs/1406.3233
The Skolem-Abouzaid theorem in the singular case
Let F(X;Y) in Q[X;Y] be a Q-irreducible polynomial. In 1929 Skolem proved the following theorem: "Assume that F(0;0) = 0. Then for every non-zero integer d, the equation F(X;Y) = 0 has only finitely many solutions in integers (X;Y) with gcd(X;Y) = d". Skolem method allows one to bound the solutions explicitly in terms ...
\section{Introduction} Let ${F(X,Y)\in\Q[X,Y]}$ be a $\Q$-irreducible polynomial. In 1929 Skolem~\cite{Sk29} proved the following beautiful theorem: \begin{theorem}[Skolem] \label{tskol} Assume that \begin{equation} \label{e00} F(0,0)=0. \end{equation} Then for every non-zero integer~$d$, the equation ${F(X,Y)=0}$...
{ "timestamp": "2015-01-22T02:15:27", "yymm": "1406", "arxiv_id": "1406.3233", "language": "en", "url": "https://arxiv.org/abs/1406.3233", "abstract": "Let F(X;Y) in Q[X;Y] be a Q-irreducible polynomial. In 1929 Skolem proved the following theorem: \"Assume that F(0;0) = 0. Then for every non-zero integer d...
https://arxiv.org/abs/1312.3311
Stochastic De Giorgi Iteration and Regularity of Stochastic Partial Differential Equation
Under general conditions we show that the solution of a stochastic parabolic partial differential equation of the form \[ \partial_t u = \mathrm{div} (A \nabla u) + f(t,x, u) + g_i (t,x,u) \dot{w}^i_t \] is almost surely Hölder continuous in both space and time variables.
\section{Introduction} Stochastic partial differential equations (SPDEs) arise in many pure and applied sciences. Regularity of solutions is of central importance for theoretical development as well as for numerical simulations. For linear equations, $W^{k,2}$-theory has been well developed (see Pardoux~\cite{Par07} ...
{ "timestamp": "2014-05-14T02:03:58", "yymm": "1312", "arxiv_id": "1312.3311", "language": "en", "url": "https://arxiv.org/abs/1312.3311", "abstract": "Under general conditions we show that the solution of a stochastic parabolic partial differential equation of the form \\[ \\partial_t u = \\mathrm{div} (A ...
https://arxiv.org/abs/1911.05799
Congruences satisfied by eta-quotients
The values of the partition function, and more generally the Fourier coefficients of many modular forms, are known to satisfy certain congruences. Results given by Ahlgren and Ono for the partition function and by Treneer for more general Fourier coefficients state the existence of infinitely many families of congruenc...
\section{Introduction}\label{sec:intro} The partition function $p(n)$ gives the number of non-increasing sequences of positive integers that sum to $n$. Ramanujan first discovered that $p(n)$ satisfies \begin{align*} p(5n+4)&\equiv 0\pmod{5},\\ p(7n+5)&\equiv 0\pmod{7}, \;\mathrm{and}\\ p(11n+6)&\equiv 0\pmod{11}, \en...
{ "timestamp": "2021-02-01T02:13:13", "yymm": "1911", "arxiv_id": "1911.05799", "language": "en", "url": "https://arxiv.org/abs/1911.05799", "abstract": "The values of the partition function, and more generally the Fourier coefficients of many modular forms, are known to satisfy certain congruences. Results...
https://arxiv.org/abs/2005.01576
Group Presentations for Links in Thickened Surfaces
Using a combinatorial argument, we prove the well-known result that the Wirtinger and Dehn presentations of a link in 3-space describe isomorphic groups. The result is not true for links $\ell$ in a thickened surface $S \times [0,1]$. Their precise relationship, as given in the 2012 thesis of R.E. Byrd, is established ...
\section{Introduction} Modern knot theory, which began in the early 1900's, was propelled by the nearly simultaneous publications of two different methods for computing presentations of knot groups, fundamental groups of knot complements. The methods are due to W. Wirtinger and M. Dehn. Both are combinatorial, beginnin...
{ "timestamp": "2020-05-05T02:32:31", "yymm": "2005", "arxiv_id": "2005.01576", "language": "en", "url": "https://arxiv.org/abs/2005.01576", "abstract": "Using a combinatorial argument, we prove the well-known result that the Wirtinger and Dehn presentations of a link in 3-space describe isomorphic groups. ...
https://arxiv.org/abs/0710.2020
Valiron's construction in higher dimension
We consider holomorphic self-maps $\v$ of the unit ball $\B^N$ in $\C^N$ ($N=1,2,3,...$). In the one-dimensional case, when $\v$ has no fixed points in $\D\defeq \B^1$ and is of hyperbolic type, there is a classical renormalization procedure due to Valiron which allows to semi-linearize the map $\phi$, and therefore, i...
\section{Introduction} \subsection{The one-dimensional case} Let $\varphi$ be a holomorphic map on $\mathbb D$ with $\varphi(\mathbb D)\subset\mathbb D$. If $\varphi$ has no fixed points in $\mathbb D$, then by the classical Wolff lemma (see, {\sl e.g.}, \cite{Abate}) there exists a unique point $\tau\in\partial\ma...
{ "timestamp": "2007-10-10T16:13:43", "yymm": "0710", "arxiv_id": "0710.2020", "language": "en", "url": "https://arxiv.org/abs/0710.2020", "abstract": "We consider holomorphic self-maps $\\v$ of the unit ball $\\B^N$ in $\\C^N$ ($N=1,2,3,...$). In the one-dimensional case, when $\\v$ has no fixed points in ...
https://arxiv.org/abs/1907.03635
Distance from the Nucleus to a Uniformly Random Point in the 0-cell and the Typical Cell of the Poisson-Voronoi Tessellation
Consider the distances $\tilde{R}_o$ and $R_o$ from the nucleus to a uniformly random point in the 0-cell and the typical cell, respectively, of the $d$-dimensional Poisson-Voronoi (PV) tessellation. The main objective of this paper is to characterize the exact distributions of $\tilde{R}_o$ and $R_o$. First, using the...
\section{Introduction}\label{sec:Intro} The Poisson point process (PPP) has found many applications in science and engineering due to its useful mathematical properties. Several of these applications specifically focus on the Poisson-Voronoi (PV) tessellation \cite{moller1989random}, which partitions space into disjo...
{ "timestamp": "2019-12-06T02:19:02", "yymm": "1907", "arxiv_id": "1907.03635", "language": "en", "url": "https://arxiv.org/abs/1907.03635", "abstract": "Consider the distances $\\tilde{R}_o$ and $R_o$ from the nucleus to a uniformly random point in the 0-cell and the typical cell, respectively, of the $d$-...
https://arxiv.org/abs/1301.2342
A Linear Time Algorithm for the Feasibility of Pebble Motion on Graphs
Given a connected, undirected, simple graph $G = (V, E)$ and $p \le |V|$ pebbles labeled $1,..., p$, a configuration of these $p$ pebbles is an injective map assigning the pebbles to vertices of $G$. Let $S$ and $D$ be two such configurations. From a configuration, pebbles can move on $G$ as follows: In each step, at m...
\section{Introduction} In Sam Loyd's 15-puzzle \cite{Loy59}, a player is asked to arrange square game pieces labeled 1-15, scrambled on a $4 \times 4$ grid, to a shuffled row major ordering, using one empty swap cell: In each step, one of the labeled pieces neighboring the empty cell may be moved to the empty cell (...
{ "timestamp": "2013-01-22T02:02:36", "yymm": "1301", "arxiv_id": "1301.2342", "language": "en", "url": "https://arxiv.org/abs/1301.2342", "abstract": "Given a connected, undirected, simple graph $G = (V, E)$ and $p \\le |V|$ pebbles labeled $1,..., p$, a configuration of these $p$ pebbles is an injective m...
https://arxiv.org/abs/2006.11612
Unstable Modules with the Top $k$ Squares
Unstable modules over the Steenrod algebra with only the top $k$ operations are introduced in the language of ringoids. We prove the category of such modules has homological dimension at most $k$. A pratical method, which generalizes the $\Lambda$ complex, to compute the $\mathrm{Ext}$ group from such modules to sphere...
\section*{Introduction} Let $A$ be the Steenrod algebra over the field $\mathbb{F}_{2}$. The purpose of this paper is to investigate the category $\mathcal{U}_{k}$ of unstable left $A$-modules where only the top $k$ Steenrod squares are allowed. In general, on an homogeneous element of degree $n$ the top $k$ Steenrod s...
{ "timestamp": "2020-06-23T02:13:06", "yymm": "2006", "arxiv_id": "2006.11612", "language": "en", "url": "https://arxiv.org/abs/2006.11612", "abstract": "Unstable modules over the Steenrod algebra with only the top $k$ operations are introduced in the language of ringoids. We prove the category of such modu...
https://arxiv.org/abs/1405.5587
Parking functions, Shi arrangements, and mixed graphs
The \emph{Shi arrangement} is the set of all hyperplanes in $\mathbb R^n$ of the form $x_j - x_k = 0$ or $1$ for $1 \le j < k \le n$. Shi observed in 1986 that the number of regions (i.e., connected components of the complement) of this arrangement is $(n+1)^{n-1}$. An unrelated combinatorial concept is that of a \emph...
\section{Introduction} Our goal is to draw (bijective) connections between three seemingly unrelated concepts; their names form the title of our paper, and we start by introducing them one by one. \subsection{Parking Functions} Imagine a one-way street with $n$ parking spots and a cliff at its end. We'll give the f...
{ "timestamp": "2014-09-09T02:11:45", "yymm": "1405", "arxiv_id": "1405.5587", "language": "en", "url": "https://arxiv.org/abs/1405.5587", "abstract": "The \\emph{Shi arrangement} is the set of all hyperplanes in $\\mathbb R^n$ of the form $x_j - x_k = 0$ or $1$ for $1 \\le j < k \\le n$. Shi observed in 19...
https://arxiv.org/abs/1306.3396
Symmetry minimizes the principal eigenvalue: an example for the Pucci's sup operator
We explicitly evaluate the principal eigenvalue of the extremal Pucci's sup--operator for a class of special plane domains, and we prove that, for fixed area, the eigenvalue is minimal for the most symmetric set.
\section{Introduction}\label{intro} In 1951, P\'olya and Szego conjectured: {\em Of all $n$-polygons with the same area, the regular $n$-polygon has the smallest first Dirichlet eigenvalue,} referring to the Dirichlet eigenvalue of the Laplacian. It is very simple to see that among all rectangles of same area, the o...
{ "timestamp": "2013-07-08T02:03:33", "yymm": "1306", "arxiv_id": "1306.3396", "language": "en", "url": "https://arxiv.org/abs/1306.3396", "abstract": "We explicitly evaluate the principal eigenvalue of the extremal Pucci's sup--operator for a class of special plane domains, and we prove that, for fixed are...
https://arxiv.org/abs/1806.07260
The graphs with all but two eigenvalues equal to $2$ or $-1$
In this paper, all graphs whose adjacency matrix has at most two eigenvalues (multiplicities included) different from $2$ and $-1$ are determined. These graphs conclude a class of generalized friendship graphs $F_{t,r,k}, $ which is the graph of $k$ copies of the complete graph $K_t$ meeting in common $r$ vertices such...
\section{ Introduction} All graphs in this paper are simple graphs and all spectrum of a graph are adjacency spectrum. Let $G=(V,E)$ be a graph. The adjacency matrix $A(G)$ (or $A$) of $G$ is an $n\times n$ matrix, whose $(i,j)$-entry is $1$ if vertex $v_{i}$ is adjacent to $v_{j}$ (denote by $v_i \sim v_j$), and is ...
{ "timestamp": "2018-06-20T02:11:23", "yymm": "1806", "arxiv_id": "1806.07260", "language": "en", "url": "https://arxiv.org/abs/1806.07260", "abstract": "In this paper, all graphs whose adjacency matrix has at most two eigenvalues (multiplicities included) different from $2$ and $-1$ are determined. These g...
https://arxiv.org/abs/1805.02201
RealCertify: a Maple package for certifying non-negativity
Let $\mathbb{Q}$ (resp. $\mathbb{R}$) be the field of rational (resp. real) numbers and $X = (X_1, \ldots, X_n)$ be variables. Deciding the non-negativity of polynomials in $\mathbb{Q}[X]$ over $\mathbb{R}^n$ or over semi-algebraic domains defined by polynomial constraints in $\mathbb{Q}[X]$ is a classical algorithmic ...
\section{Introduction} Let ${\mathbb{Q}}$ (resp.~${\mathbb{R}}$) be the field of rational (resp.~real) numbers and $X = (X_1, \ldots, X_n)$ be a sequence of variables. We consider the problem of deciding the non-negativity of $f \in {\mathbb{Q}}[X]$ either over ${\mathbb{R}}^n$ or over a semi-algebraic set $S$ defined...
{ "timestamp": "2018-05-08T02:11:12", "yymm": "1805", "arxiv_id": "1805.02201", "language": "en", "url": "https://arxiv.org/abs/1805.02201", "abstract": "Let $\\mathbb{Q}$ (resp. $\\mathbb{R}$) be the field of rational (resp. real) numbers and $X = (X_1, \\ldots, X_n)$ be variables. Deciding the non-negativ...
https://arxiv.org/abs/1907.00551
Plateau's problem as a singular limit of capillarity problems
Soap films at equilibrium are modeled, rather than as surfaces, as regions of small total volume through the introduction of a capillarity problem with a homotopic spanning condition. This point of view introduces a length scale in the classical Plateau's problem, which is in turn recovered in the vanishing volume limi...
\section{Introduction} \subsection{Overview}\label{section overview} The theory of minimal surfaces with prescribed boundary data provides the basic model for soap films hanging from a wire frame: given an $(n-1)$-dimensional surface $\Gamma\subset\mathbb{R}^{n+1}$ without boundary, one seeks $n$-dimensional surfaces ...
{ "timestamp": "2021-05-05T02:18:23", "yymm": "1907", "arxiv_id": "1907.00551", "language": "en", "url": "https://arxiv.org/abs/1907.00551", "abstract": "Soap films at equilibrium are modeled, rather than as surfaces, as regions of small total volume through the introduction of a capillarity problem with a ...
https://arxiv.org/abs/2207.06074
Optimal Reach Estimation and Metric Learning
We study the estimation of the reach, an ubiquitous regularity parameter in manifold estimation and geometric data analysis. Given an i.i.d. sample over an unknown $d$-dimensional $\mathcal{C}^k$-smooth submanifold of $\mathbb{R}^D$, we provide optimal nonasymptotic bounds for the estimation of its reach. We build upon...
\subsection{Geometric Inference} Topological data analysis and geometric methods now constitute a standard toolbox in statistics and machine learning~\cite{Wasserman18,Chazal21}. In this family of methods, data $\mathbb{X}_n := \{X_1,\dots,X_n\}$ are usually seen as point clouds in high dimension, for which complex st...
{ "timestamp": "2022-07-14T02:12:44", "yymm": "2207", "arxiv_id": "2207.06074", "language": "en", "url": "https://arxiv.org/abs/2207.06074", "abstract": "We study the estimation of the reach, an ubiquitous regularity parameter in manifold estimation and geometric data analysis. Given an i.i.d. sample over a...
https://arxiv.org/abs/1707.04247
On the maximum diameter of path-pairable graphs
A graph is path-pairable if for any pairing of its vertices there exist edge disjoint paths joining the vertices in each pair. We obtain sharp bounds on the maximum possible diameter of path-pairable graphs which either have a given number of edges, or are c- degenerate. Along the way we show that a large family of gra...
\section{Introduction} \emph{Path-pairability} is a graph theoretical notion that emerged from a practical networking problem introduced by Csaba, Faudree, Gy\'arf\'as, Lehel, and Schelp \cite{CS}, and further studied by Faudree, Gy\'arf\'as, and Lehel \cite{mpp,F,pp} and by Kubicka, Kubicki and Lehel \cite{grid}. Give...
{ "timestamp": "2017-07-14T02:07:51", "yymm": "1707", "arxiv_id": "1707.04247", "language": "en", "url": "https://arxiv.org/abs/1707.04247", "abstract": "A graph is path-pairable if for any pairing of its vertices there exist edge disjoint paths joining the vertices in each pair. We obtain sharp bounds on t...
https://arxiv.org/abs/1812.11169
Spherical harmonic d-tensors
Tensor harmonics are a useful mathematical tool for finding solutions to differential equations which transform under a particular representation of the rotation group $\mathrm{SO}(3)$. The aim of this work is to make use of this tool also in the setting of Finsler geometry, or more general geometries on the tangent bu...
\section{Introduction}\label{sec:intro} It is commonly understood that problems in differential geometry and its applications in physics simplify if they exhibit any symmetries, such as spherical or planar symmetries, which are most common to appear in physics via the action of a corresponding symmetry group on some un...
{ "timestamp": "2018-12-31T02:21:06", "yymm": "1812", "arxiv_id": "1812.11169", "language": "en", "url": "https://arxiv.org/abs/1812.11169", "abstract": "Tensor harmonics are a useful mathematical tool for finding solutions to differential equations which transform under a particular representation of the r...
https://arxiv.org/abs/0801.4726
Stochastic extrema as stationary phases of characteristic functions
The paper is dealing with semi-classical asymptotics of a characteristic function for a stochastic process. The main technical tool is provided by the stationary phase method. The extremal range for a stochastic process is defined by limit values of the complex logarithm of the characteristic function. The paper also o...
\section{INTRODUCTION} The extremum for a stochastic process admits transparent numerical presentation in terms of limit set of its characteristic function which is treated as a high frequency integral \cite{Guillemin}, \cite{McClure}, \cite{Maslov}, \cite{Maslov_Fedoriuk}. The proposed concept of stochastic extremum ...
{ "timestamp": "2008-01-30T18:35:40", "yymm": "0801", "arxiv_id": "0801.4726", "language": "en", "url": "https://arxiv.org/abs/0801.4726", "abstract": "The paper is dealing with semi-classical asymptotics of a characteristic function for a stochastic process. The main technical tool is provided by the stati...
https://arxiv.org/abs/1204.6530
Independent sets in hypergraphs
Many important theorems in combinatorics, such as Szemerédi's theorem on arithmetic progressions and the Erdős-Stone Theorem in extremal graph theory, can be phrased as statements about independent sets in uniform hypergraphs. In recent years, an important trend in the area has been to extend such classical results to ...
\section{Introduction} A great many of the central questions in combinatorics fall into the following general framework: Given a finite set $V$ and a collection $\mathcal{H} \subseteq \mathcal{P}(V)$ of \emph{forbidden structures}, what can be said about sets $I \subseteq V$ that do not contain any member of $\mathcal...
{ "timestamp": "2014-03-24T01:07:52", "yymm": "1204", "arxiv_id": "1204.6530", "language": "en", "url": "https://arxiv.org/abs/1204.6530", "abstract": "Many important theorems in combinatorics, such as Szemerédi's theorem on arithmetic progressions and the Erdős-Stone Theorem in extremal graph theory, can b...
https://arxiv.org/abs/1403.7920
Computing the dimension of ideals in group algebras, with an application to coding theory
The problem of computing the dimension of a left/right ideal in a group algebra F[G] of a finite group G over a field F is considered. The ideal dimension is related to the rank of a matrix originating from a regular left/right representation of G; in particular, when F[G] is semisimple, the dimension of a principal id...
\section{Introduction and preliminaries}\label{sect1} Let $\mathcal G=\{g_1,g_2, \ldots,g_n\}$ be a finite multiplicative group of order $n=|\mathcal G|$, with neutral element $g_1=1$. Let $\mathbb F$ be a field of characteristic $p$. Finite fields of order $q=p^m$ are denoted as $\mathbb F_q$. The group algebra...
{ "timestamp": "2014-04-01T02:13:40", "yymm": "1403", "arxiv_id": "1403.7920", "language": "en", "url": "https://arxiv.org/abs/1403.7920", "abstract": "The problem of computing the dimension of a left/right ideal in a group algebra F[G] of a finite group G over a field F is considered. The ideal dimension i...
https://arxiv.org/abs/1608.01596
Heat kernel estimates on connected sums of parabolic manifolds
We obtain matching two sided estimates of the heat kernel on a connected sum of parabolic manifolds, each of them satisfying the Li-Yau estimate. The key result is the on-diagonal upper bound of the heat kernel at a central point. Contrary to the nonparabolic case (which was settled in [15]), the on-diagonal behavior o...
\section{Introduction} \label{Introduction} Let $M$ be a Riemannian manifold. The heat kernel $p(t,x,y)$ on $M$ is the minimal positive fundamental solution of the heat equation $\partial _{t}u=\Delta u$ on $M$ where $u=u\left( t,x\right) $, $t>0$, $x\in M$ and $% \Delta $ is the (negative definite) Laplace-Beltrami...
{ "timestamp": "2016-08-05T02:09:59", "yymm": "1608", "arxiv_id": "1608.01596", "language": "en", "url": "https://arxiv.org/abs/1608.01596", "abstract": "We obtain matching two sided estimates of the heat kernel on a connected sum of parabolic manifolds, each of them satisfying the Li-Yau estimate. The key ...
https://arxiv.org/abs/2212.10759
The construction of $ε$-splitting map
For a geodesic ball with non-negative Ricci curvature and almost maximal volume, without using compactness argument, we construct an $\epsilon$-splitting map on a concentric geodesic ball with uniformly small radius. There are two new technical points in our proof. The first one is the way of finding $n$ directional po...
\section{Introduction} For a compact $n$-dimensional Riemannian manifold with $Rc\geq (n- 1)$, if its volume is close to the volume of unit round sphere $\mathbb{S}^{n}$, Colding \cite{Colding-shape} proved that the manifold is Gromov-Hausdorff close to $\mathbb{S}^{n}$. Analogue to the positive Ricci curvature case, ...
{ "timestamp": "2022-12-22T02:06:40", "yymm": "2212", "arxiv_id": "2212.10759", "language": "en", "url": "https://arxiv.org/abs/2212.10759", "abstract": "For a geodesic ball with non-negative Ricci curvature and almost maximal volume, without using compactness argument, we construct an $\\epsilon$-splitting...
https://arxiv.org/abs/1809.06296
Improvements for eigenfunction averages: An application of geodesic beams
Let $(M,g)$ be a smooth, compact Riemannian manifold and $\{\phi_\lambda \}$ an $L^2$-normalized sequence of Laplace eigenfunctions, $-\Delta_g\phi_\lambda =\lambda^2 \phi_\lambda$. Given a smooth submanifold $H \subset M$ of codimension $k\geq 1$, we find conditions on the pair $(M,H)$, even when $H=\{x\}$, for which ...
\section{Introduction} On a smooth compact Riemannian manifold without boundary of dimension $n$, $(M,g)$, we consider sequences of Laplace eigenfunctions $\{\phi_\lambda\}$ solving \[ (-\Delta_g-\lambda^2)\phi_\lambda=0,\qquad{\|\phi_\lambda\|_{L^2(M)}=1.} \] We study the average oscillatory behavior of $\phi_\lambd...
{ "timestamp": "2019-03-22T01:07:21", "yymm": "1809", "arxiv_id": "1809.06296", "language": "en", "url": "https://arxiv.org/abs/1809.06296", "abstract": "Let $(M,g)$ be a smooth, compact Riemannian manifold and $\\{\\phi_\\lambda \\}$ an $L^2$-normalized sequence of Laplace eigenfunctions, $-\\Delta_g\\phi_...
https://arxiv.org/abs/2106.11573
Approximation convergence in the inverse first-passage time problem
The inverse first-passage time problem determines a boundary such that the first-passage time of a Wiener process to this boundary has a given distribution. An approximation which is based on the starting value of the boundary to a smooth boundary by a piecewise linear boundary is given by equating the probability of t...
\section{Introduction} In the theory of stochastic processes, first-passage time related problems have been studied extensively. When specified to a standard Brownian motion $(W_t)_{t \geq 0}$, the related first passage to an upper boundary continuous function $g: \mathbb{R}^+ \rightarrow \mathbb{R}$ satisfying $g(0) \...
{ "timestamp": "2021-06-23T02:12:53", "yymm": "2106", "arxiv_id": "2106.11573", "language": "en", "url": "https://arxiv.org/abs/2106.11573", "abstract": "The inverse first-passage time problem determines a boundary such that the first-passage time of a Wiener process to this boundary has a given distributio...
https://arxiv.org/abs/1610.07232
Symbolic Iterative Solution of Two-Point Boundary Value Problems
In this work we give an efficient method involving symbolic manipulation, Picard iteration, and auxiliary variables for approximating solutions of two-point boundary value problems.
\section{Introduction}\label{s:intro} There exist a variety of numerical methods for approximating solutions of two-point boundary value problems, among them shooting methods, finite difference techniques, power series methods, and variational methods, all of which are described in detail in classical texts (for examp...
{ "timestamp": "2016-10-25T02:07:02", "yymm": "1610", "arxiv_id": "1610.07232", "language": "en", "url": "https://arxiv.org/abs/1610.07232", "abstract": "In this work we give an efficient method involving symbolic manipulation, Picard iteration, and auxiliary variables for approximating solutions of two-poi...
https://arxiv.org/abs/1710.09301
The Loewner Equation for Multiple Hulls
Kager, Nienhuis, and Kadanoff conjectured that the hull generated from the Loewner equation driven by two constant functions with constant weights could be generated by a single rapidly and randomly oscillating function. We prove their conjecture and generalize to multiple continuous driving functions. In the process, ...
\section{Introduction} The Loewner equation is the initial value problem \begin{equation}\label{eqn:LEintro} \frac{\partial}{\partial t} g_t(z) =\frac{2}{g_t(z)-\lambda(t)}, \quad g_0(z)=z. \end{equation} where $\lambda:[0,T]\to\mathbb{R}$ is called the driving function. For $z\in\mathbb{H}$, a solution ex...
{ "timestamp": "2017-10-26T02:09:02", "yymm": "1710", "arxiv_id": "1710.09301", "language": "en", "url": "https://arxiv.org/abs/1710.09301", "abstract": "Kager, Nienhuis, and Kadanoff conjectured that the hull generated from the Loewner equation driven by two constant functions with constant weights could b...
https://arxiv.org/abs/math/0612552
Isomorphisms between Leavitt algebras and their matrix rings
Let $K$ be any field, let $L_n$ denote the Leavitt algebra of type $(1,n-1)$ having coefficients in $K$, and let ${\rm M}_d(L_n)$ denote the ring of $d \times d$ matrices over $L_n$. In our main result, we show that ${\rm M}_d(L_n) \cong L_n$ if and only if $d$ and $n-1$ are coprime. We use this isomorphism to answer a...
\section*{Introduction} Let $K$ be any field, and let $m<n$ be positive integers. The ring $R$ is said to have {\it invariant basis number} (IBN) if no two free left $R$-modules of differing rank over $R$ are isomorphic. On the other hand, $R$ is said to have {\it module type} $(m,n-m)$ in case for every pair of posit...
{ "timestamp": "2008-02-22T14:00:05", "yymm": "0612", "arxiv_id": "math/0612552", "language": "en", "url": "https://arxiv.org/abs/math/0612552", "abstract": "Let $K$ be any field, let $L_n$ denote the Leavitt algebra of type $(1,n-1)$ having coefficients in $K$, and let ${\\rm M}_d(L_n)$ denote the ring of ...
https://arxiv.org/abs/1112.5206
Vanishing of negative $K$-theory in positive characteristic
We show how a theorem of Gabber on alterations can be used to apply work of Cisinski, Suslin, Voevodsky, and Weibel to prove that $K_n(X)[1/p] = 0$ for $n < - \dim X$ where $X$ is a quasi-excellent noetherian scheme, $p$ is a prime that is nilpotent on $X$, and $K_n$ is the $K$-theory of Bass-Thomason-Trobaugh. This gi...
\section{Introduction} In \cite[2.9]{Wei80} Weibel asks if $K_n(X) = 0$ for $n < - \dim X$ for every noetherian scheme $X$ where $K_n$ is the $K$-theory of Bass-Thomason-Trobaugh. This question was answered in the affirmative in \cite{CHSW} for schemes essentially of finite type over a field of characteristic zero. As...
{ "timestamp": "2013-05-24T02:02:42", "yymm": "1112", "arxiv_id": "1112.5206", "language": "en", "url": "https://arxiv.org/abs/1112.5206", "abstract": "We show how a theorem of Gabber on alterations can be used to apply work of Cisinski, Suslin, Voevodsky, and Weibel to prove that $K_n(X)[1/p] = 0$ for $n <...
https://arxiv.org/abs/math/0502402
Topological fundamental groups can distinguish spaces with isomorphic homotopy groups
We exhibit a map f between aspherical spaces X and Y such that f induces an isomorphism on homotopy groups but, with natural topologies, X and Y fail to have homeomorphic fundamental groups. Thus the topological fundamental group has the capacity to distinguish homotopy type when the Whitehead theorem fails.
\section{Introduction} Given CW complexes $X$ and $Y,$ the Whitehead theorem (\cite{hatch}) asserts that a map $f:X\rightarrow Y$ is a homotopy equivalence provided $f$ induces an isomorphism on homotopy groups. However the result can fail in the context of path connected metric spaces. For example the standard Warsaw...
{ "timestamp": "2005-04-19T22:26:04", "yymm": "0502", "arxiv_id": "math/0502402", "language": "en", "url": "https://arxiv.org/abs/math/0502402", "abstract": "We exhibit a map f between aspherical spaces X and Y such that f induces an isomorphism on homotopy groups but, with natural topologies, X and Y fail ...
https://arxiv.org/abs/2301.05414
Higher order first integrals of autonomous non-Riemannian dynamical systems
We consider autonomous holonomic dynamical systems defined by equations of the form $\ddot{q}^{a}=-\Gamma_{bc}^{a}(q) \dot{q}^{b}\dot{q}^{c}$ $-Q^{a}(q)$, where $\Gamma^{a}_{bc}(q)$ are the coefficients of a symmetric (possibly non-metrical) connection and $-Q^{a}(q)$ are the generalized forces. We prove a theorem whic...
\section{Introduction} \label{sec.intro} A first integral (FI) of a second order set of dynamical equations with generalized coordinates $q^{a}$ and generalized velocities $\dot{q}^{a}\equiv \frac{dq^{a}}{dt}$ is a function $I(t,q^{a},\dot{q}^{a})$ satisfying the condition $\frac{dI}{dt}=0$ along the dynamical eq...
{ "timestamp": "2023-01-16T02:06:30", "yymm": "2301", "arxiv_id": "2301.05414", "language": "en", "url": "https://arxiv.org/abs/2301.05414", "abstract": "We consider autonomous holonomic dynamical systems defined by equations of the form $\\ddot{q}^{a}=-\\Gamma_{bc}^{a}(q) \\dot{q}^{b}\\dot{q}^{c}$ $-Q^{a}(...
https://arxiv.org/abs/math/9805098
On Dynamics of Cubic Siegel Polynomials
Motivated by the work of Douady, Ghys, Herman and Shishikura on Siegel quadratic polynomials, we study the one-dimensional slice of the cubic polynomials which have a fixed Siegel disk of rotation number theta, with theta being a given irrational number of Brjuno type. Our main goal is to prove that when theta is of bo...
\section{A Blaschke Parameter Space} \label{sec:blapar} Now we focus on a certain class of degree $5$ Blaschke products. These are the maps $B$ with the following two properties:\\ \begin{enumerate} \item[(i)] $B$ has the form \begin{equation} \label{eqn:blass} B:z\mapsto e^{2 \pi i t} z^3 \left ( \frac{z-p}{1-\ov...
{ "timestamp": "1998-05-22T00:05:37", "yymm": "9805", "arxiv_id": "math/9805098", "language": "en", "url": "https://arxiv.org/abs/math/9805098", "abstract": "Motivated by the work of Douady, Ghys, Herman and Shishikura on Siegel quadratic polynomials, we study the one-dimensional slice of the cubic polynomi...
https://arxiv.org/abs/1109.1857
Some remarks about interpolating sequences in reproducing kernel Hilbert spaces
In this paper we study two separate problems on interpolation. We first give some new equivalences of Stout's Theorem on necessary and sufficient conditions for a sequence of points to be an interpolating sequence on a finite open Riemann surface. We next turn our attention to the question of interpolation for reproduc...
\section*{Notation} \section{Introduction and Statement of Main Results} Recall that a sequence $Z=\{z_j\}\subset\mathbb{D}$ is called an $H^\infty$-\textit{interpolating} sequence if for every $a=\{a_j\}\in\ell^\infty$ there exists a function $f\in H^\infty$ such that $$ f(z_j)=a_j\quad\forall j. $$ Similarly, for t...
{ "timestamp": "2013-04-23T02:02:49", "yymm": "1109", "arxiv_id": "1109.1857", "language": "en", "url": "https://arxiv.org/abs/1109.1857", "abstract": "In this paper we study two separate problems on interpolation. We first give some new equivalences of Stout's Theorem on necessary and sufficient conditions...
https://arxiv.org/abs/math/0604457
On some properties of contracting matrices
The concepts of paracontracting, pseudocontracting and nonexpanding operators have been shown to be useful in proving convergence of asynchronous or parallel iteration algorithms. The purpose of this paper is to give characterizations of these operators when they are linear and finite-dimensional. First we show that ps...
\section{Introduction\label{sec:introduction}} \begin{definition}[\cite{nelson:paracontractive:1987}] Let $\|\cdot\|$ be a vector norm in ${\mathbb C}^n$. An $n$ by $n$ matrix $B$ is {\em nonexpansive} with respect to $\|\cdot\|$ if \begin{equation}\label{eqn:noncontractive} \forall x \in {\mathbb C}^n, \|Bx\|\leq \|...
{ "timestamp": "2006-04-20T22:33:18", "yymm": "0604", "arxiv_id": "math/0604457", "language": "en", "url": "https://arxiv.org/abs/math/0604457", "abstract": "The concepts of paracontracting, pseudocontracting and nonexpanding operators have been shown to be useful in proving convergence of asynchronous or p...
https://arxiv.org/abs/1702.06068
On a problem of Pethő
In this paper we deal with a problem of Pethő related to existence of quartic algebraic integer $\alpha$ for which $$ \beta=\frac{4\alpha^4}{\alpha^4-1}-\frac{\alpha}{\alpha-1} $$ is a quadratic algebraic number. By studying rational solutions of certain Diophantine system we prove that there are infinitely many $\alph...
\section{introduction} Buchmann and Peth\H{o} \cite{BuPe} found an interesting unit in the number field $K=\mathbb{Q}(\alpha)$ with $\alpha^7-3=0$ it is as follows $$ 10+9\alpha+8\alpha^2+7\alpha^3+6\alpha^4+5\alpha^5+4\alpha^6. $$ That is the coordinates $(x_0,\ldots,x_6)\in\mathbb{Z}^7$ of a solution of the norm form...
{ "timestamp": "2017-03-16T01:05:18", "yymm": "1702", "arxiv_id": "1702.06068", "language": "en", "url": "https://arxiv.org/abs/1702.06068", "abstract": "In this paper we deal with a problem of Pethő related to existence of quartic algebraic integer $\\alpha$ for which $$ \\beta=\\frac{4\\alpha^4}{\\alpha^4...
https://arxiv.org/abs/1712.09335
Restricted families of projections in vector spaces over finite fields
We study the restricted families of projections in vector spaces over finite fields. We show that there are families of random subspaces which admit a Marstrand-Mattila type projection theorem.
\section{Introduction} A fundamental problem in fractal geometry is to determine how the projections affect dimension. Recall the classical Marstrand-Mattila projection theorem: Let $E\subset \mathbb{R}^{n}, n\geq2,$ be a Borel set with Hausdorff dimension $s$. \begin{itemize} \item (dimension part) If $s\leq m$, the...
{ "timestamp": "2017-12-29T02:00:14", "yymm": "1712", "arxiv_id": "1712.09335", "language": "en", "url": "https://arxiv.org/abs/1712.09335", "abstract": "We study the restricted families of projections in vector spaces over finite fields. We show that there are families of random subspaces which admit a Mar...
https://arxiv.org/abs/1509.06029
Capacity and Expressiveness of Genomic Tandem Duplication
The majority of the human genome consists of repeated sequences. An important type of repeated sequences common in the human genome are tandem repeats, where identical copies appear next to each other. For example, in the sequence $AGTC\underline{TGTG}C$, $TGTG$ is a tandem repeat, that may be generated from $AGTCTGC$ ...
\section{Introduction}\label{sec:introduction} More than $50\%$ of the human genome consists of repeated sequences~\cite{Lander}. Two important types of common repeats are i) interspersed repeats and ii) tandem repeats. Interspersed repeats are caused by transposons. A transposon (jumping gene) is a segment of DNA th...
{ "timestamp": "2015-09-22T02:11:37", "yymm": "1509", "arxiv_id": "1509.06029", "language": "en", "url": "https://arxiv.org/abs/1509.06029", "abstract": "The majority of the human genome consists of repeated sequences. An important type of repeated sequences common in the human genome are tandem repeats, wh...
https://arxiv.org/abs/2012.13288
Answer to an open question concerning the $1/e$-strategy for best choice under no information
This paper answers a long-standing open question concerning the $1/e$-strategy for the problem of best choice. $N$ candidates for a job arrive at times independently uniformly distributed in $[0,1]$. The interviewer knows how each candidate ranks relative to all others seen so far, and must immediately appoint or rejec...
\section{Dedication and background} At the evening of Professor Larry Shepp's talk ``Reflecting Brownian Motion" at Cornell University on July 11, 1983 (13th Conference on Stochastic Processes and Applications), Professor Shepp and Thomas Bruss ran into each other in front of the Ezra Cornell statue. Thomas was hono...
{ "timestamp": "2020-12-25T02:13:51", "yymm": "2012", "arxiv_id": "2012.13288", "language": "en", "url": "https://arxiv.org/abs/2012.13288", "abstract": "This paper answers a long-standing open question concerning the $1/e$-strategy for the problem of best choice. $N$ candidates for a job arrive at times in...
https://arxiv.org/abs/2201.12441
Family-wise error rate control in Gaussian graphical model selection via Distributionally Robust Optimization
Recently, a special case of precision matrix estimation based on a distributionally robust optimization (DRO) framework has been shown to be equivalent to the graphical lasso. From this formulation, a method for choosing the regularization term, i.e., for graphical model selection, was proposed. In this work, we establ...
\section{Introduction}\label{sec1} The estimation of the precision matrix $\Omega=\Sigma^{-1}$ of a Gaussian random vector $X \in \mathbb{R}^d$ with covariance matrix $\Sigma$ is a problem that has received much attention in statistics and machine learning \citep{dempster1972, Drton-Perlman, MY-LY:07, Drton2017}. The ...
{ "timestamp": "2022-02-01T02:04:24", "yymm": "2201", "arxiv_id": "2201.12441", "language": "en", "url": "https://arxiv.org/abs/2201.12441", "abstract": "Recently, a special case of precision matrix estimation based on a distributionally robust optimization (DRO) framework has been shown to be equivalent to...
https://arxiv.org/abs/1801.09367
Approximate Vanishing Ideal via Data Knotting
The vanishing ideal is a set of polynomials that takes zero value on the given data points. Originally proposed in computer algebra, the vanishing ideal has been recently exploited for extracting the nonlinear structures of data in many applications. To avoid overfitting to noisy data, the polynomials are often designe...
\section{Introduction} Bridging computer algebra and various applications such as machine learning, computer vision, and systems biology has been attracting interest over the past decade~\cite{torrente2009application,laubenbacher2009computer,li2011theory,livni2013vanishing,vera2014algebra,gao2016nonlinear}. Borrowed f...
{ "timestamp": "2018-01-30T02:10:35", "yymm": "1801", "arxiv_id": "1801.09367", "language": "en", "url": "https://arxiv.org/abs/1801.09367", "abstract": "The vanishing ideal is a set of polynomials that takes zero value on the given data points. Originally proposed in computer algebra, the vanishing ideal h...
https://arxiv.org/abs/1602.00418
Lifting Problem on Automorphism Groups of Cyclic Curves
Let X be a smooth projective hyperelliptic curve over an algeraically closed field k of prime characteristic p. The aim of this note is to find necessary and sufficient conditions on the automorphism group of the curve X to be lifted to characteristic zero. The results will be generalised for a certain family of curves...
\section{Introduction} Let $k$ be an algebraically closed field of prime characteristic $p.$ Given a smooth projective curve $X$ over $k,$ consider a lifting $(X_0/k_0, v)$ of $X/k$ to characteristic $0,$ with the following properties: \begin{itemize} \item $k_0$ is the algebraically closed field of the fraction field...
{ "timestamp": "2016-02-02T02:13:43", "yymm": "1602", "arxiv_id": "1602.00418", "language": "en", "url": "https://arxiv.org/abs/1602.00418", "abstract": "Let X be a smooth projective hyperelliptic curve over an algeraically closed field k of prime characteristic p. The aim of this note is to find necessary ...
https://arxiv.org/abs/math/0604459
A Reproducing Kernel Condition for Indeterminacy in the Multidimensional Moment Problem
Using the smallest eigenvalues of Hankel forms associated with a multidimensional moment problem, we establish a condition equivalent to the existence of a reproducing kernel. This result is a multivariate analogue of Berg, Chen,and Ismail's 2002 result. We also present a class of measures for which the existence of a ...
\section{Introduction} In \cite{BCI}, Berg, Chen, and Ismail find a new condition equivalent to determinacy in the one-dimensional moment problem. \begin{theorem}[Berg, Chen, and Ismail, 2002] \label{T:BCI} Let $\lambda_N$ be the smallest eigenvalue of the truncated Hankel matrix $H_N$ for the measure $\mu$. Then ...
{ "timestamp": "2007-02-02T17:35:08", "yymm": "0604", "arxiv_id": "math/0604459", "language": "en", "url": "https://arxiv.org/abs/math/0604459", "abstract": "Using the smallest eigenvalues of Hankel forms associated with a multidimensional moment problem, we establish a condition equivalent to the existence...
https://arxiv.org/abs/2112.08678
Asymptotically Optimal Golay-ZCZ Sequence Sets with Flexible Length
Zero correlation zone (ZCZ) sequences and Golay complementary sequences are two kinds of sequences with different preferable correlation properties. Golay-ZCZ sequences are special kinds of complementary sequences which also possess a large ZCZ and are good candidates for pilots in OFDM systems. Known Golay-ZCZ sequenc...
\section{Introduction}\label{section 1} Golay complementary sets (GCS) and zero correlation zone (ZCZ) sequence sets are two kinds of sequence sets with different desirable correlation properties. GCS are sequence sets have zero aperiodic autocorrelation sums (AACS) at all non-zero time shifts \cite{Golay61}, whereas Z...
{ "timestamp": "2021-12-17T02:12:00", "yymm": "2112", "arxiv_id": "2112.08678", "language": "en", "url": "https://arxiv.org/abs/2112.08678", "abstract": "Zero correlation zone (ZCZ) sequences and Golay complementary sequences are two kinds of sequences with different preferable correlation properties. Golay...
https://arxiv.org/abs/1708.07593
Exotic Bifurcations Inspired by Walking Droplet Dynamics
We identify two rather novel types of (compound) dynamical bifurcations generated primarily by interactions of an invariant attracting submanifold with stable and unstable manifolds of hyperbolic fixed points. These bifurcation types - inspired by recent investigations of mathematical models for walking droplet (pilot-...
\section{Introduction} Inspired by our recent research on the dynamical properties of mathematical models of walking droplet (pilot-wave) phenomena \cite{RB1}, we shall describe and analyze what appear to be new types or classes of bifurcations. Owing largely to its potential for producing macroscopic analogs of cert...
{ "timestamp": "2017-08-28T02:02:13", "yymm": "1708", "arxiv_id": "1708.07593", "language": "en", "url": "https://arxiv.org/abs/1708.07593", "abstract": "We identify two rather novel types of (compound) dynamical bifurcations generated primarily by interactions of an invariant attracting submanifold with st...
https://arxiv.org/abs/math/0512297
Empty simplices of polytopes and graded Betti numbers
The conjecture of Kalai, Kleinschmidt, and Lee on the number of empty simplices of a simplicial polytope is established by relating it to the first graded Betti numbers of the polytope. The proof allows us to derive explicit optimal bounds on the number of empty simplices of any given dimension. As a key result, we pro...
\section{Introduction} Let $P \subset \mathbb{R}^d$ be a simplicial $d$-polytope, i.e.\ the $d$-dimensional convex hull of finitely many points in $\mathbb{R}^d$ such that all its faces are simplices. The simplest combinatorial invariant of $P$ is its $f$-vector $\underline{f} = (f_{-1}, f_0,\ldots, f_{d-1})$ where $f...
{ "timestamp": "2005-12-14T02:24:34", "yymm": "0512", "arxiv_id": "math/0512297", "language": "en", "url": "https://arxiv.org/abs/math/0512297", "abstract": "The conjecture of Kalai, Kleinschmidt, and Lee on the number of empty simplices of a simplicial polytope is established by relating it to the first gr...
https://arxiv.org/abs/2106.02334
Statistics for Unimodal Sequences
We prove a number of limiting distributions for statistics for unimodal sequences of positive integers by adapting a probabilistic framework for integer partitions introduced by Fristedt. The difficulty in applying the direct analogue of Fristedt's techniques to unimodal sequences lies in the fact that the generating f...
\section{Introduction and Statement of results} A {\it partition} $\lambda$ of $n$ is a sequence of positive integers that sum to $n$, $$ \lambda: \qquad \lambda_1 \geq \dots \geq \lambda_{\ell} > 0, \qquad \sum_{k=1}^{\ell} \lambda_k=n. $$ We write $|\lambda|=n$ for the {\it size} of $\lambda$, set $p(n):= \#\{\lamb...
{ "timestamp": "2021-06-07T02:14:48", "yymm": "2106", "arxiv_id": "2106.02334", "language": "en", "url": "https://arxiv.org/abs/2106.02334", "abstract": "We prove a number of limiting distributions for statistics for unimodal sequences of positive integers by adapting a probabilistic framework for integer p...
https://arxiv.org/abs/1707.00837
Computation of Green's functions through algebraic decomposition of operators
In this article we use linear algebra to improve the computational time for the obtaining of Green's functions of linear differential equations with reflection (DER). This is achieved by decomposing both the `reduced' equation (the ODE associated to a given DER) and the corresponding two-point boundary conditions.
\section{Introduction} Differential operators with reflection have recently been of great interest, partly due to their applications to Supersymmetric Quantum Mechanics \cite{Post, Roy, Gam} or topological methods applied to nonlinear analysis \cite{Cab5}.\par In the last years the works in this field have been related...
{ "timestamp": "2017-07-05T02:03:15", "yymm": "1707", "arxiv_id": "1707.00837", "language": "en", "url": "https://arxiv.org/abs/1707.00837", "abstract": "In this article we use linear algebra to improve the computational time for the obtaining of Green's functions of linear differential equations with refle...
https://arxiv.org/abs/1805.03075
Goal oriented time adaptivity using local error estimates
We consider initial value problems where we are interested in a quantity of interest (QoI) that is the integral in time of a functional of the solution of the IVP. For these, we look into local error based time adaptivity. We derive a goal oriented error estimate and timestep controller, based on error contribution to ...
\section{Introduction}\label{intro} A typical situation in numerical simulations based on differential equations is that one is not interested in the solution of the differential equation per se, but a \textit{Quantity of Interest} (QoI) that is given as a functional of the solution. For example, when designing an airp...
{ "timestamp": "2018-05-09T02:10:34", "yymm": "1805", "arxiv_id": "1805.03075", "language": "en", "url": "https://arxiv.org/abs/1805.03075", "abstract": "We consider initial value problems where we are interested in a quantity of interest (QoI) that is the integral in time of a functional of the solution of...
https://arxiv.org/abs/1110.1737
Graded Morita equivalence of Clifford superalgebras
This note uses a variation of graded Morita theory for finite dimensional superalgebras to determine explicitly the graded basic superalgebras for all real and complex Clifford superalgebras. As an application, the Grothendieck groups of the category of left $\mathbb{Z}_2$-graded modules over all real and complex Cliff...
\section{Introduction} Clifford (super)algebras or special Grassmann (super)algebras play an important role in many branches of mathematics such as Clifford analysis, algebras, mathematics physics, geometry and topology etc., see for example \cite{abs,V}. For the finite dimensional superalgebras, there is a natural...
{ "timestamp": "2012-04-20T02:03:09", "yymm": "1110", "arxiv_id": "1110.1737", "language": "en", "url": "https://arxiv.org/abs/1110.1737", "abstract": "This note uses a variation of graded Morita theory for finite dimensional superalgebras to determine explicitly the graded basic superalgebras for all real ...
https://arxiv.org/abs/1301.5882
Geometric homology revisited
Given a cohomology theory, there is a well-known abstract way to define the dual homology theory using the theory of spectra. In [4] the author provides a more geometric construction of the homology theory, using a generalization of the bordism groups. Such a generalization involves in its definition the vector bundle ...
\section{Introduction} Given a cohomology theory $h^{\bullet}$, there is a well-known abstract way to define the dual homology theory $h_{\bullet}$, using the theory of spectra. In particular, if $h^{\bullet}$ is representable via a spectrum $E = \{E_{n}, e_{n}, \varepsilon_{n}\}_{n \in \mathbb{Z}}$, for $e_{n}$ the...
{ "timestamp": "2013-01-25T02:03:06", "yymm": "1301", "arxiv_id": "1301.5882", "language": "en", "url": "https://arxiv.org/abs/1301.5882", "abstract": "Given a cohomology theory, there is a well-known abstract way to define the dual homology theory using the theory of spectra. In [4] the author provides a m...
https://arxiv.org/abs/2206.09844
Heavy-traffic single-server queues and the transform method
Heavy-traffic limit theory deals with queues that operate close to criticality and face severe queueing times. Let $W$ denote the steady-state waiting time in the ${\rm GI}/{\rm G}/1$ queue. Kingman (1961) showed that $W$, when appropriately scaled, converges in distribution to an exponential random variable as the sys...
\section{Introduction and results} \label{sec1} {The title of this contribution to the memorial issue for J.W.~Cohen refers to the The Single-Server Queue, the monumental book \cite{cohen2012single} in which J.W.~Cohen teaches the reader how to use complex analysis and transform methods to obtain mathematical rigorous...
{ "timestamp": "2022-06-22T02:33:27", "yymm": "2206", "arxiv_id": "2206.09844", "language": "en", "url": "https://arxiv.org/abs/2206.09844", "abstract": "Heavy-traffic limit theory deals with queues that operate close to criticality and face severe queueing times. Let $W$ denote the steady-state waiting tim...
https://arxiv.org/abs/1903.00470
Geometric and Probabilistic Limit Theorems in Topological Data Analysis
We develop a general framework for the probabilistic analysis of random finite point clouds in the context of topological data analysis. We extend the notion of a barcode of a finite point cloud to compact metric spaces. Such a barcode lives in the completion of the space of barcodes with respect to the bottleneck dist...
\subsection{This subsection is numbered but not shown in the toc} \begin{document} \title{Geometric and Probabilistic Limit Theorems in Topological Data Analysis} \author{Sara~Kali\v{s}nik, Christian Lehn, and Vlada Limic} \begin{abstract} We develop a general framework for the probabilistic analysis of random fini...
{ "timestamp": "2020-06-29T02:11:16", "yymm": "1903", "arxiv_id": "1903.00470", "language": "en", "url": "https://arxiv.org/abs/1903.00470", "abstract": "We develop a general framework for the probabilistic analysis of random finite point clouds in the context of topological data analysis. We extend the not...
https://arxiv.org/abs/1305.6461
Observation of vibrating systems at different time instants
In this paper, we obtain new observability inequalities for the vibrating string. This work was motivated by a recent paper by A. Szijártó and J. Hegedűs in which the authors ask the question of determining the initial data by only knowing the position of the string at two distinct time instants. The choice of the obse...
\section{Introduction} Let $q$ be a nonnegative number. The small transversal vibrations of a string of length $\pi$ fixed at its two ends satisfy \footnote{ The quantity $y=y(t,x)$ is the height of the string at time $t$ and abscissa $x$ while $y(t)$ stands for the map $y(t,\cdot)$. The choice of $\pi$ for the leng...
{ "timestamp": "2013-05-29T02:01:33", "yymm": "1305", "arxiv_id": "1305.6461", "language": "en", "url": "https://arxiv.org/abs/1305.6461", "abstract": "In this paper, we obtain new observability inequalities for the vibrating string. This work was motivated by a recent paper by A. Szijártó and J. Hegedűs in...
https://arxiv.org/abs/1801.02340
Lifting a prescribed group of automorphisms of graphs
In this paper we are interested in lifting a prescribed group of automorphisms of a finite graph via regular covering projections. Here we describe with an example the problems we address and refer to the introductory section for the correct statements of our results.Let $P$ be the Petersen graph, say, and let $\wp:\ti...
\section{Introduction} Covering projections of graphs and lifting automorphisms along them is a classical tool in algebraic graph theory that goes back to Djokovi\'c and his proof of the infinitude of cubic $5$-arc-transitive graphs~\cite{Dj1}. Moreover, several theoretical aspects of lifting graph automorphisms alon...
{ "timestamp": "2018-01-09T02:11:51", "yymm": "1801", "arxiv_id": "1801.02340", "language": "en", "url": "https://arxiv.org/abs/1801.02340", "abstract": "In this paper we are interested in lifting a prescribed group of automorphisms of a finite graph via regular covering projections. Here we describe with a...
https://arxiv.org/abs/2212.08291
Drivers, hitting times, and weldings in Loewner's equation
In addition to conformal weldings $\varphi$, simple curves $\gamma$ growing in the upper half plane generate driving functions $\xi$ and hitting times $\tau$ through Loewner's differential equation. While the Loewner transform $\gamma \mapsto \xi$ and its inverse $\xi \mapsto \gamma$ have been carefully examined, less ...
\section{Introduction and main results} \subsection{Loewner's equation and associated functions} A hundred years ago, Charles Loewner \cite{Loewner1923} showed the evolution of maps $g_t$ from the slit disk $\mathbb{D} \backslash \gamma([0,t])$ back to $\mathbb{D}$, where $\gamma$ is a curve growing into $\mathbb{D}...
{ "timestamp": "2022-12-19T02:06:47", "yymm": "2212", "arxiv_id": "2212.08291", "language": "en", "url": "https://arxiv.org/abs/2212.08291", "abstract": "In addition to conformal weldings $\\varphi$, simple curves $\\gamma$ growing in the upper half plane generate driving functions $\\xi$ and hitting times ...
https://arxiv.org/abs/2208.06324
On the Connectivity and Diameter of Geodetic Graphs
A graph $G$ is geodetic if between any two vertices there exists a unique shortest path. In 1962 Ore raised the challenge to characterize geodetic graphs, but despite many attempts, such characterization still seems well beyond reach. We may assume, of course, that $G$ is $2$-connected, and here we consider only graphs...
\section{Geodetic Graphs and Connectivity} In this section we prove \autoref{No2Connected}. From here on we assume $G$ is geodetic with $\delta(G)\ge 3$. We denote the (unique) $v,u$ geodesic in $G$ by $\pi(v,u)$, and by convention we enumerate its vertices in order from $v$ to $u$. Arguing by contradiction, let $S=\{x...
{ "timestamp": "2022-08-15T02:13:16", "yymm": "2208", "arxiv_id": "2208.06324", "language": "en", "url": "https://arxiv.org/abs/2208.06324", "abstract": "A graph $G$ is geodetic if between any two vertices there exists a unique shortest path. In 1962 Ore raised the challenge to characterize geodetic graphs,...
https://arxiv.org/abs/math/0608063
The Maslov class of Lagrangian tori and quantum products in Floer cohomology
We use Floer cohomology to prove the monotone version of a conjecture of Audin: the minimal Maslov number of a monotone Lagrangian torus in C^n is 2. Our approach is based on the study of the quantum cup product on Floer cohomology and in particular the behaviour of Oh's spectral sequence with respect to this product. ...
\section{Introduction and main results} \label{S:intro} Let $(M, \omega)$ be a tame symplectic manifold (see ~\cite{A-L-P}, also Section ~\ref{S:basic notions}). The class of tame symplectic manifolds includes compact manifolds, Stein manifolds, and more generally, manifolds which are symplectically convex at infini...
{ "timestamp": "2009-12-04T20:41:00", "yymm": "0608", "arxiv_id": "math/0608063", "language": "en", "url": "https://arxiv.org/abs/math/0608063", "abstract": "We use Floer cohomology to prove the monotone version of a conjecture of Audin: the minimal Maslov number of a monotone Lagrangian torus in C^n is 2. ...
https://arxiv.org/abs/1508.04126
Basis construction for range estimation by phase unwrapping
We consider the problem of estimating the distance, or range, between two locations by measuring the phase of a sinusoidal signal transmitted between the locations. This method is only capable of unambiguously measuring range within an interval of length equal to the wavelength of the signal. To address this problem si...
\section{Introduction}\label{sec:intro} \newcommand{\operatorname{lcm}}{\operatorname{lcm}} Range (or distance) estimation is an important component of modern technologies such as electronic surveying~\cite{Jacobs_ambiguity_resolution_interferometery_1981, anderson1998surveying} and global positioning~\cite{Teunisse...
{ "timestamp": "2015-08-18T02:16:40", "yymm": "1508", "arxiv_id": "1508.04126", "language": "en", "url": "https://arxiv.org/abs/1508.04126", "abstract": "We consider the problem of estimating the distance, or range, between two locations by measuring the phase of a sinusoidal signal transmitted between the ...
https://arxiv.org/abs/1202.4121
Properties of pointed and connected Hopf algebras of finite Gelfand-Kirillov dimension
Let $H$ be a pointed Hopf algebra. We show that under some mild assumptions $H$ and its associated graded Hopf algebra $\gr H$ have the same Gelfand-Kirillov dimension. As an application, we prove that the Gelfand-Kirillov dimension of a connected Hopf algebra is either infinity or a positive integer. We also classify ...
\part{Use this type of header for very long papers only} \section{Introductioin} The Gelfand-Kirillov dimension (or GK-dimension for short) has been a useful tool for investigating infinite-dimensional Hopf algebras. For example, Hopf algebras of low GK-dimensions are studied in \cite{BZ,GZ,Li,Z,WZZ1,WZZ2}. It is ...
{ "timestamp": "2012-11-20T02:01:44", "yymm": "1202", "arxiv_id": "1202.4121", "language": "en", "url": "https://arxiv.org/abs/1202.4121", "abstract": "Let $H$ be a pointed Hopf algebra. We show that under some mild assumptions $H$ and its associated graded Hopf algebra $\\gr H$ have the same Gelfand-Kirill...
https://arxiv.org/abs/1704.08160
From Fixed-X to Random-X Regression: Bias-Variance Decompositions, Covariance Penalties, and Prediction Error Estimation
In statistical prediction, classical approaches for model selection and model evaluation based on covariance penalties are still widely used. Most of the literature on this topic is based on what we call the "Fixed-X" assumption, where covariate values are assumed to be nonrandom. By contrast, it is often more reasonab...
\section{Introduction} A statistical regression model seeks to describe the relationship between a response $y \in \mathbb{R}$ and a covariate vector $x \in \mathbb{R}^p$, based on training data comprised of paired observations $(x_1,y_1),\ldots,(x_n,y_n)$. Many modern regression models are ultimately aimed at predict...
{ "timestamp": "2017-06-13T02:04:36", "yymm": "1704", "arxiv_id": "1704.08160", "language": "en", "url": "https://arxiv.org/abs/1704.08160", "abstract": "In statistical prediction, classical approaches for model selection and model evaluation based on covariance penalties are still widely used. Most of the ...
https://arxiv.org/abs/1509.08145
Linear Arrangement of Halin Graphs
We study the Optimal Linear Arrangement (OLA) problem of Halin graphs, one of the simplest classes of non-outerplanar graphs. We present several properties of OLA of general Halin graphs. We prove a lower bound on the cost of OLA of any Halin graph, and define classes of Halin graphs for which the cost of OLA matches t...
\section{Introduction} \label{sect:intro} \input{introduction} \section{Preliminaries} \label{sect:prelim} \input{preliminaries} \section{Some Properties of OLA of Halin Graphs} \label{sect:OLA-halin-graphs} \input{OLA-halin-graphs} \section{Halin Graphs With Polynomially Solvable LA Algorithm} \la...
{ "timestamp": "2015-09-29T02:14:42", "yymm": "1509", "arxiv_id": "1509.08145", "language": "en", "url": "https://arxiv.org/abs/1509.08145", "abstract": "We study the Optimal Linear Arrangement (OLA) problem of Halin graphs, one of the simplest classes of non-outerplanar graphs. We present several propertie...
https://arxiv.org/abs/1205.3266
On the 1-2-3-conjecture
A k-edge-weighting of a graph G is a function w: E(G)->{1,2,...,k}. An edge-weighting naturally induces a vertex coloring c, where for every vertex v in V(G), c(v) is sum of weights of the edges that are adjacent to vertex v. If the induced coloring c is a proper vertex coloring, then w is called a vertex-coloring k-ed...
\section{\hspace*{-.6cm}. Introduction} In this paper, we consider finite and simple graphs. A \textit{$r$-vertex coloring} $c$ of $G$ is a function $c:V(G)\rightarrow\{1,2,\ldots ,r\}$. The coloring $c$ is called a \textit{proper vertex coloring} if for every two adjacent vertices $u$ and $v$, $c(u)\neq c(v)$. A graph...
{ "timestamp": "2012-05-16T02:02:19", "yymm": "1205", "arxiv_id": "1205.3266", "language": "en", "url": "https://arxiv.org/abs/1205.3266", "abstract": "A k-edge-weighting of a graph G is a function w: E(G)->{1,2,...,k}. An edge-weighting naturally induces a vertex coloring c, where for every vertex v in V(G...
https://arxiv.org/abs/2106.06510
Measuring the robustness of Gaussian processes to kernel choice
Gaussian processes (GPs) are used to make medical and scientific decisions, including in cardiac care and monitoring of atmospheric carbon dioxide levels. Notably, the choice of GP kernel is often somewhat arbitrary. In particular, uncountably many kernels typically align with qualitative prior knowledge (e.g.\ functio...
\section{Code assets used} \label{app:resourcesUsed} Our experiments use the following dependencies which are listed alongside their license details: \begin{enumerate} \item \texttt{NumPy} \cite{numpy}, which uses the BSD 3-Clause ``New'' or ``Revised'' License. \item \texttt{jax} \cite{jax2018_github}, which uses ...
{ "timestamp": "2021-06-14T02:28:49", "yymm": "2106", "arxiv_id": "2106.06510", "language": "en", "url": "https://arxiv.org/abs/2106.06510", "abstract": "Gaussian processes (GPs) are used to make medical and scientific decisions, including in cardiac care and monitoring of atmospheric carbon dioxide levels....
https://arxiv.org/abs/2211.08939
Augmented Physics-Informed Neural Networks (APINNs): A gating network-based soft domain decomposition methodology
In this paper, we propose the augmented physics-informed neural network (APINN), which adopts soft and trainable domain decomposition and flexible parameter sharing to further improve the extended PINN (XPINN) as well as the vanilla PINN methods. In particular, a trainable gate network is employed to mimic the hard dec...
\section{Introduction} Deep learning has become popular in scientific computing and is widely adopted in solving forward and inverse problems involving partial differential equations (PDEs). The physics-informed neural network (PINN) \cite{raissi2019physics} is one of the seminal works in utilizing deep neural networks...
{ "timestamp": "2022-11-24T02:15:00", "yymm": "2211", "arxiv_id": "2211.08939", "language": "en", "url": "https://arxiv.org/abs/2211.08939", "abstract": "In this paper, we propose the augmented physics-informed neural network (APINN), which adopts soft and trainable domain decomposition and flexible paramet...
https://arxiv.org/abs/0708.2336
Unsatisfiable Linear k-CNFs Exist, for every k
We call a CNF formula linear if any two clauses have at most one variable in common. Let Linear k-SAT be the problem of deciding whether a given linear k-CNF formula is satisfiable. Here, a k-CNF formula is a CNF formula in which every clause has size exactly k. It was known that for k >= 3, Linear k-SAT is NP-complete...
\section{Introduction} A CNF formula $F$ (conjunctive normal form) over a variable set $V$ is a set of clauses; a clause is a set of literals; a literal is either a variable $x \in V$ or its negation $\bar{x}$. A CNF formula $F$, or short, a CNF $F$, is called a $k$-CNF if $|C| = k$ for every $C \in F$. Define $\ens...
{ "timestamp": "2007-08-17T11:44:21", "yymm": "0708", "arxiv_id": "0708.2336", "language": "en", "url": "https://arxiv.org/abs/0708.2336", "abstract": "We call a CNF formula linear if any two clauses have at most one variable in common. Let Linear k-SAT be the problem of deciding whether a given linear k-CN...
https://arxiv.org/abs/0901.4389
Spectral fluctuation properties of constrained unitary ensembles of Gaussian-distributed random matrices
We investigate the spectral fluctuation properties of constrained ensembles of random matrices (defined by the condition that a number N(Q) of matrix elements vanish identically; that condition is imposed in unitarily invariant form) in the limit of large matrix dimension. We show that as long as N(Q) is smaller than a...
\section{Introduction} \label{int} We investigate the spectral fluctuation properties of the constrained unitary ensembles of Gaussian--distributed random matrices (CGUE) introduced in Ref.~\cite{Pap06}. Constrained ensembles of random matrices deserve interest because they represent entire classes of non--canonical r...
{ "timestamp": "2009-01-28T13:55:54", "yymm": "0901", "arxiv_id": "0901.4389", "language": "en", "url": "https://arxiv.org/abs/0901.4389", "abstract": "We investigate the spectral fluctuation properties of constrained ensembles of random matrices (defined by the condition that a number N(Q) of matrix elemen...
https://arxiv.org/abs/1407.8336
Induced Matchings in Graphs of Maximum Degree 4
For a graph $G$, let $\nu_s(G)$ be the induced matching number of $G$. We prove the sharp bound $\nu_s(G)\geq \frac{n(G)}{9}$ for every graph $G$ of maximum degree at most $4$ and without isolated vertices that does not contain a certain blown up $5$-cycle as a component. This result implies a consequence of the well k...
\section{Introduction} For a graph $G$, a set $M$ of edges is an \emph{induced matching} of $G$ if no two edges in $M$ have a common endvertex and no edge of $G$ joins two edges in $M$. The maximum number of edges that form an induced matching in $G$ is the {\it strong matching number $\nu_s(G)$ of $G$}. Unl...
{ "timestamp": "2014-08-01T02:07:51", "yymm": "1407", "arxiv_id": "1407.8336", "language": "en", "url": "https://arxiv.org/abs/1407.8336", "abstract": "For a graph $G$, let $\\nu_s(G)$ be the induced matching number of $G$. We prove the sharp bound $\\nu_s(G)\\geq \\frac{n(G)}{9}$ for every graph $G$ of max...
https://arxiv.org/abs/1610.05674
The $p$-curvature conjecture and monodromy about simple closed loops
The Grothendieck-Katz $p$-curvature conjecture is an analogue of the Hasse Principle for differential equations. It states that a set of arithmetic differential equations on a variety has finite monodromy if its $p$-curvature vanishes modulo $p$, for almost all primes $p$. We prove that if the variety is a generic curv...
\section{Introduction} The Grothendieck-Katz $p$-curvature conjecture posits the existence of a full set of algebraic solutions to arithmetic differential equations in characteristic 0, given the existence of solutions after reducing modulo a prime for almost all primes. More precisely, let $R \subset \mathbb{C}$ be ...
{ "timestamp": "2016-10-19T02:07:40", "yymm": "1610", "arxiv_id": "1610.05674", "language": "en", "url": "https://arxiv.org/abs/1610.05674", "abstract": "The Grothendieck-Katz $p$-curvature conjecture is an analogue of the Hasse Principle for differential equations. It states that a set of arithmetic differ...
https://arxiv.org/abs/1511.03828
Multiply union families in $\mathbb{N}^n$
Let $A\subset \mathbb{N}^{n}$ be an $r$-wise $s$-union family, that is, a family of sequences with $n$ components of non-negative integers such that for any $r$ sequences in $A$ the total sum of the maximum of each component in those sequences is at most $s$. We determine the maximum size of $A$ and its unique extremal...
\section{Introduction} Let $\N:=\{0,1,2,\ldots\}$ denote the set of non-negative integers, and let $[n]:=\{1,2,\ldots,n\}$. Intersecting families in $2^{[n]}$ or $\{0,1\}^n$ are one of the main objects in extremal set theory. The equivalent dual form of an intersecting family is a union family, which is the subjec...
{ "timestamp": "2016-06-03T02:05:35", "yymm": "1511", "arxiv_id": "1511.03828", "language": "en", "url": "https://arxiv.org/abs/1511.03828", "abstract": "Let $A\\subset \\mathbb{N}^{n}$ be an $r$-wise $s$-union family, that is, a family of sequences with $n$ components of non-negative integers such that for...
https://arxiv.org/abs/1612.09083
A Constant Optimization of the Binary Indexed Tree Query Operation
There are several data structures which can calculate the prefix sums of an array efficiently, while handling point updates on the array, such as Segment Trees and Binary Indexed Trees (BIT). Both these data structures can handle the these two operations (query and update) in $O(\log{n})$ time. In this paper, we presen...
\section{Problem Motivation} A Prefix Sum is defined as the sum of the first $n$ elements of an array, where $ 1 \leq n \leq size(array) $. The problem can be traditionally solved on an array $arr$ by creating a prefix sum array $pre$ such that \begin{equation} pre[1] = arr[1] \end{equation} \begin{equation} ...
{ "timestamp": "2016-12-30T02:06:54", "yymm": "1612", "arxiv_id": "1612.09083", "language": "en", "url": "https://arxiv.org/abs/1612.09083", "abstract": "There are several data structures which can calculate the prefix sums of an array efficiently, while handling point updates on the array, such as Segment ...
https://arxiv.org/abs/1801.07634
Khovanov homology detects the trefoils
We prove that Khovanov homology detects the trefoils. Our proof incorporates an array of ideas in Floer homology and contact geometry. It uses open books; the contact invariants we defined in the instanton Floer setting; a bypass exact triangle in sutured instanton homology, proven here; and Kronheimer and Mrowka's spe...
\section{Introduction} \label{sec:intro} Khovanov homology assigns to a knot $K\subset S^3$ a bigraded abelian group \[\Kh(K)=\bigoplus_{i,j}\Kh^{i,j}(K)\] whose graded Euler characteristic recovers the Jones polynomial of $K$. In their landmark paper \cite{km-khovanov}, Kronheimer and Mrowka proved that Khovanov hom...
{ "timestamp": "2018-01-24T02:10:59", "yymm": "1801", "arxiv_id": "1801.07634", "language": "en", "url": "https://arxiv.org/abs/1801.07634", "abstract": "We prove that Khovanov homology detects the trefoils. Our proof incorporates an array of ideas in Floer homology and contact geometry. It uses open books;...
https://arxiv.org/abs/2210.11770
Hamilton completion and the path cover number of sparse random graphs
We prove that for every $\varepsilon > 0$ there is $c_0$ such that if $G\sim G(n,c/n)$, $c\ge c_0$, then with high probability $G$ can be covered by at most $(1+\varepsilon)\cdot \frac{1}{2}ce^{-c} \cdot n$ vertex disjoint paths, which is essentially tight. This is equivalent to showing that, with high probability, at ...
\section{Introduction} \label{sec-intro} A classical result by Koml\'{o}s and Szemer\'{e}di \cite{KS83}, and independently by Bollob\'{a}s \cite{B84}, states that if $p=p(n)=(\log n + \log \log n + f(n))/n$ then \begin{eqnarray*} \lim _{n\to \infty} \mathbb{P} (G(n,p)\text{ is Hamiltonian}) = \begin{cases} 1...
{ "timestamp": "2022-10-24T02:08:43", "yymm": "2210", "arxiv_id": "2210.11770", "language": "en", "url": "https://arxiv.org/abs/2210.11770", "abstract": "We prove that for every $\\varepsilon > 0$ there is $c_0$ such that if $G\\sim G(n,c/n)$, $c\\ge c_0$, then with high probability $G$ can be covered by at...
https://arxiv.org/abs/1511.00166
Extension of Chebfun to periodic functions
Algorithms and underlying mathematics are presented for numerical computation with periodic functions via approximations to machine precision by trigonometric polynomials, including the solution of linear and nonlinear periodic ordinary differential equations. Differences from the nonperiodic Chebyshev case are highlig...
\section{Introduction} It is well known that trigonometric representations of periodic functions and Chebyshev polynomial representations of nonperiodic functions are closely related. Table~\ref{parallels} lists some of the parallels between these two situations. Chebfun, a software system for computing with fun...
{ "timestamp": "2015-11-03T02:10:18", "yymm": "1511", "arxiv_id": "1511.00166", "language": "en", "url": "https://arxiv.org/abs/1511.00166", "abstract": "Algorithms and underlying mathematics are presented for numerical computation with periodic functions via approximations to machine precision by trigonome...
https://arxiv.org/abs/2106.12726
Images of multilinear polynomials on $n\times n$ upper triangular matrices over infinite fields
In this paper we prove that the image of multilinear polynomials evaluated on the algebra $UT_n(K)$ of $n\times n$ upper triangular matrices over an infinite field $K$ equals $J^r$, a power of its Jacobson ideal $J=J(UT_n(K))$. In particular, this shows that the analogue of the Lvov-Kaplansky conjecture for $UT_n(K)$ i...
\section{Introduction} Let $K$ be an infinite field and let $M_n(K)$ denote the algebra of $n\times n$ matrices over $K$. A famous problem known as Lvov-Kaplansky conjecture asserts: the image of a multilinear polynomial (in noncommutative variables) on $M_n(K)$ is a vector space. It is well-known that this is equiv...
{ "timestamp": "2021-06-25T02:07:23", "yymm": "2106", "arxiv_id": "2106.12726", "language": "en", "url": "https://arxiv.org/abs/2106.12726", "abstract": "In this paper we prove that the image of multilinear polynomials evaluated on the algebra $UT_n(K)$ of $n\\times n$ upper triangular matrices over an infi...
https://arxiv.org/abs/2212.12072
Completing the solution of the directed Oberwolfach problem with cycles of equal length
In this paper, we give a solution to the last outstanding case of the directed Oberwolfach problem with tables of uniform length. Namely, we address the two-table case with tables of odd length. We prove that the complete symmetric digraph on $2m$ vertices, denoted $K^*_{2m}$, admits a resolvable decomposition into dir...
\section{Introduction} In this paper, we address the last open case of the directed Oberwolfach problem with tables of uniform length, namely the case with two tables of odd length. A variation of the celebrated Oberwolfach problem, the directed Oberwolfach problem asks whether $t$ conference attendees can be seated a...
{ "timestamp": "2023-01-03T02:19:48", "yymm": "2212", "arxiv_id": "2212.12072", "language": "en", "url": "https://arxiv.org/abs/2212.12072", "abstract": "In this paper, we give a solution to the last outstanding case of the directed Oberwolfach problem with tables of uniform length. Namely, we address the t...
https://arxiv.org/abs/1204.6422
Conflict-free coloring with respect to a subset of intervals
Given a hypergraph H = (V, E), a coloring of its vertices is said to be conflict-free if for every hyperedge S \in E there is at least one vertex in S whose color is distinct from the colors of all other vertices in S. The discrete interval hypergraph Hn is the hypergraph with vertex set {1,...,n} and hyperedge set the...
\section{Introduction \label{sec:intro} A hypergraph $H$ is a pair $(V,\E)$, where $V$ is a finite set and $\E$ is a family of non-empty subsets of $V$. We denote by $\Positives$ the set of positive integers and by $\Naturals$ the set of non-negative integers. \begin{definition}\label{def:origcf} Let $H=(...
{ "timestamp": "2012-05-01T02:02:25", "yymm": "1204", "arxiv_id": "1204.6422", "language": "en", "url": "https://arxiv.org/abs/1204.6422", "abstract": "Given a hypergraph H = (V, E), a coloring of its vertices is said to be conflict-free if for every hyperedge S \\in E there is at least one vertex in S whos...
https://arxiv.org/abs/1902.08165
The harmonicity of slice regular functions
In this article we investigate harmonicity, Laplacians, mean value theorems and related topics in the context of quaternionic analysis. We observe that a Mean Value Formula for slice regular functions holds true and it is a consequence of the well known Representation Formula for slice regular functions over $\mathbb{H...
\section{Introduction} In \cite{gentilistruppa1} and \cite{gentilistruppa}, Gentili and Struppa gave the following definition of {\it slice regular function} over the quaternions: \begin{definition} Let $\Omega$ be a domain in $\H$. A real differentiable function $f \colon \Omega \to \H $ is said to be slice regular ...
{ "timestamp": "2020-10-19T02:14:35", "yymm": "1902", "arxiv_id": "1902.08165", "language": "en", "url": "https://arxiv.org/abs/1902.08165", "abstract": "In this article we investigate harmonicity, Laplacians, mean value theorems and related topics in the context of quaternionic analysis. We observe that a ...
https://arxiv.org/abs/2209.12540
The Generalized Cluster Complex: Refined Enumeration of Faces and Related Parking Spaces
The generalized cluster complex was introduced by Fomin and Reading, as a natural extension of the Fomin-Zelevinsky cluster complex coming from finite type cluster algebras. In this work, to each face of this complex we associate a parabolic conjugacy class of the underlying finite Coxeter group. We show that the refin...
\section{Introduction} The {\it cluster complex} of a finite type cluster algebra was introduced by Fomin and Zelevinsky~\cite{fominzelevinsky}. It is a simplicial complex, which can be built using {\it almost positive roots} as its vertex set. It can be seen as the dual of a corresponding {\it associahedron}. A na...
{ "timestamp": "2022-09-27T02:27:54", "yymm": "2209", "arxiv_id": "2209.12540", "language": "en", "url": "https://arxiv.org/abs/2209.12540", "abstract": "The generalized cluster complex was introduced by Fomin and Reading, as a natural extension of the Fomin-Zelevinsky cluster complex coming from finite typ...
https://arxiv.org/abs/2011.13808
Asymptotic behavior and zeros of the Bernoulli polynomials of the second kind
The main aim of this article is a careful investigation of the asymptotic behavior of zeros of Bernoulli polynomials of the second kind. It is shown that the zeros are all real and simple. The asymptotic expansions for the small, large, and the middle zeros are computed in more detail. The analysis is based on the asym...
\section{Introduction} The Bernoulli polynomials of the second kind $b_{n}$ are defined by the generating function \begin{equation} \sum_{n=0}^{\infty}b_{n}(x)\frac{t^{n}}{n!}=\frac{t}{\ln(1+t)}(1+t)^{x}, \quad |t|<1. \label{eq:gener_func_BP_sec} \end{equation} Up to a shift, they coincide with the generalized Bernou...
{ "timestamp": "2020-11-30T02:34:08", "yymm": "2011", "arxiv_id": "2011.13808", "language": "en", "url": "https://arxiv.org/abs/2011.13808", "abstract": "The main aim of this article is a careful investigation of the asymptotic behavior of zeros of Bernoulli polynomials of the second kind. It is shown that ...
https://arxiv.org/abs/math/0603131
Two step flag manifolds and the Horn conjecture
We give a simplification of Belkale's geometric proof of the Horn conjecture. Our approach uses the geometry of two-step flag manifolds to explain the occurrence of the Horn inequalities in a very straightforward way. The arguments for both necessity and sufficiency of the Horn inequalities are fairly conceptual when v...
\section{Introduction} \subsection{General approach} Horn's conjecture \cite{H} was originally formulated as a recursive method for solving a problem concerning the eigenvalues of Hermitian matrices. However, as a consequence of work of Klyachko \cite{Kly}, Horn's conjecture can be reformulated as saying that the n...
{ "timestamp": "2006-03-09T21:01:01", "yymm": "0603", "arxiv_id": "math/0603131", "language": "en", "url": "https://arxiv.org/abs/math/0603131", "abstract": "We give a simplification of Belkale's geometric proof of the Horn conjecture. Our approach uses the geometry of two-step flag manifolds to explain the...
https://arxiv.org/abs/1508.06985
Bilevel Polynomial Programs and Semidefinite Relaxation Methods
A bilevel program is an optimization problem whose constraints involve another optimization problem. This paper studies bilevel polynomial programs (BPPs), i.e., all the functions are polynomials. We reformulate BPPs equivalently as semi-infinite polynomial programs (SIPPs), using Fritz John conditions and Jacobian rep...
\section{Introduction} We consider the {\it bilevel polynomial program} (BPP): \begin{equation} \label{bilevel:pp} (P): \left\{ \begin{aligned} F^* := \min\limits_{x\in \mathbb{R}^n,y\in \mathbb{R}^p}&\ F(x,y) \\ \text{s.t.} \quad &\ G_i(x,y)\geq 0, \, i=1,\cdots,m_1, \\ & \ y\in S(x), \end{aligned} \right. \end{equ...
{ "timestamp": "2016-11-04T01:02:04", "yymm": "1508", "arxiv_id": "1508.06985", "language": "en", "url": "https://arxiv.org/abs/1508.06985", "abstract": "A bilevel program is an optimization problem whose constraints involve another optimization problem. This paper studies bilevel polynomial programs (BPPs)...
https://arxiv.org/abs/1803.00281
Strong subgraph $k$-connectivity bounds
Let $D=(V,A)$ be a digraph of order $n$, $S$ a subset of $V$ of size $k$ and $2\le k\leq n$. Strong subgraphs $D_1, \dots , D_p$ containing $S$ are said to be internally disjoint if $V(D_i)\cap V(D_j)=S$ and $A(D_i)\cap A(D_j)=\emptyset$ for all $1\le i<j\le p$. Let $\kappa_S(D)$ be the maximum number of internally dis...
\section{Introduction}\label{sec:intro} The generalized $k$-connectivity $\kappa_k(G)$ of a graph $G=(V,E)$ was introduced by Hager \cite{Hager} in 1985 ($2\le k\le |V|$). For a graph $G=(V,E)$ and a set $S\subseteq V$ of at least two vertices, an {\em $S$-Steiner tree} or, simply, an {\em $S$-tree} is a subgraph $T$...
{ "timestamp": "2018-03-02T02:08:20", "yymm": "1803", "arxiv_id": "1803.00281", "language": "en", "url": "https://arxiv.org/abs/1803.00281", "abstract": "Let $D=(V,A)$ be a digraph of order $n$, $S$ a subset of $V$ of size $k$ and $2\\le k\\leq n$. Strong subgraphs $D_1, \\dots , D_p$ containing $S$ are sai...
https://arxiv.org/abs/1404.0595
Lyapunov functions via Whitney's size functions
In this paper we present a technique for constructing Lyapunov functions based on Whitney's size functions. Applications to asymptotically stable equilibrium points, isolated sets, expansive homeomorphisms and continuum-wise expansive homeomorphisms are given.
\section{Introduction} In Dynamical Systems and Differential Equations it is important to determine the stability of trajectories and a well known technique for this purpose is to find a Lyapunov function. In order to fix ideas consider a continuous flow $\phi\colon \mathbb{R}\times X\to X$ on a compact metric space...
{ "timestamp": "2014-04-03T02:09:49", "yymm": "1404", "arxiv_id": "1404.0595", "language": "en", "url": "https://arxiv.org/abs/1404.0595", "abstract": "In this paper we present a technique for constructing Lyapunov functions based on Whitney's size functions. Applications to asymptotically stable equilibriu...
https://arxiv.org/abs/2006.14525
Conjugation Curvature in Solvable Baumslag-Solitar Groups
For an element in $BS(1,n) = \langle t,a | tat^{-1} = a^n \rangle$ written in the normal form $t^{-u}a^vt^w$ with $u,w \geq 0$ and $v \in \mathbb{Z}$, we exhibit a geodesic word representing the element and give a formula for its word length with respect to the generating set $\{t,a\}$. Using this word length formula, ...
\section{Introduction} The notion of discrete Ricci curvature for Cayley graphs of finitely generated groups was introduced by Bar-Natan, Duchin and Kropholler in \cite{BDK} as {\em conjugation curvature}. Their work is based on that of Ollivier on metric Ricci curvature for graphs and non-manifold geometries \cite{YO...
{ "timestamp": "2020-06-26T02:18:04", "yymm": "2006", "arxiv_id": "2006.14525", "language": "en", "url": "https://arxiv.org/abs/2006.14525", "abstract": "For an element in $BS(1,n) = \\langle t,a | tat^{-1} = a^n \\rangle$ written in the normal form $t^{-u}a^vt^w$ with $u,w \\geq 0$ and $v \\in \\mathbb{Z}$...
https://arxiv.org/abs/physics/0612217
How to Choose a Champion
League competition is investigated using random processes and scaling techniques. In our model, a weak team can upset a strong team with a fixed probability. Teams play an equal number of head-to-head matches and the team with the largest number of wins is declared to be the champion. The total number of games needed f...
\section{Introduction} Competition is ubiquitous in physical, biological, sociological, and economical processes. Examples include ordering kinetics where large domains grow at the expense of small ones \cite{gss,ajb}, evolution where fitter species thrive at the expense of weaker species \cite{sjg}, social stratific...
{ "timestamp": "2006-12-22T04:22:18", "yymm": "0612", "arxiv_id": "physics/0612217", "language": "en", "url": "https://arxiv.org/abs/physics/0612217", "abstract": "League competition is investigated using random processes and scaling techniques. In our model, a weak team can upset a strong team with a fixed...
https://arxiv.org/abs/2007.06652
On even entries in the character table of the symmetric group
We show that almost every entry in the character table of $S_n$ is even as $n\to\infty$. This resolves a conjecture of Miller. We similarly prove that almost every entry in the character table of $S_n$ is zero modulo $3,5,7,11,$ and $13$ as $n\to\infty$, partially addressing another conjecture of Miller.
\section{Introduction}\label{sec1} In~\cite{Miller2019}, Miller conjectured that the proportion of odd entries in the character table of $S_n$ goes to zero as $n$ goes to infinity, based on computational data for $n$ up to $76$. It has been known for a long time, due to work of McKay~\cite{McKay1972}, that only a va...
{ "timestamp": "2020-07-28T02:24:31", "yymm": "2007", "arxiv_id": "2007.06652", "language": "en", "url": "https://arxiv.org/abs/2007.06652", "abstract": "We show that almost every entry in the character table of $S_n$ is even as $n\\to\\infty$. This resolves a conjecture of Miller. We similarly prove that a...
https://arxiv.org/abs/2012.09792
Deciding when two curves are of the same type
Given two closed curves in a surface, we propose an algorithm to detect whether they are of the same type or not.
\section{Introduction} Whitehead's algorithm \cite{MR1503309} serves to determine if two elements $\gamma$ and $\eta$ in a finitely generated non-abelian free group $\BF$ differ by an automorphism of the latter, that is if there is $\phi\in\Aut(\BF)$ with $\phi(\gamma)=\eta$. An algorithm solving the same problem for ...
{ "timestamp": "2020-12-18T02:28:17", "yymm": "2012", "arxiv_id": "2012.09792", "language": "en", "url": "https://arxiv.org/abs/2012.09792", "abstract": "Given two closed curves in a surface, we propose an algorithm to detect whether they are of the same type or not.", "subjects": "Geometric Topology (mat...
https://arxiv.org/abs/2111.02471
Generalized Integer Splines on Arbitrary Graphs
Generalized integer splines on a graph $G$ with integer edge weights are integer vertex labelings such that if two vertices share an edge in $G$, the vertex labels are congruent modulo the edge weight. We introduce collapsing operations that reduce any simple graph to a single vertex, carrying with it the edge weight i...
\section{Paths to Zero} Of particular interest are the so-called \textbf{paths to zero}. To introduce these, we recall the following ideas from graph theory: \begin{definition} Let $G$ be a graph with vertex set $V$ and edge set $E$. A \textbf{path in $G$} is a sequence of vertices and edges $\mathcal{P} = \left\{p_...
{ "timestamp": "2021-11-05T01:02:02", "yymm": "2111", "arxiv_id": "2111.02471", "language": "en", "url": "https://arxiv.org/abs/2111.02471", "abstract": "Generalized integer splines on a graph $G$ with integer edge weights are integer vertex labelings such that if two vertices share an edge in $G$, the vert...
https://arxiv.org/abs/1108.0622
The rational cohomology of the mapping class group vanishes in its virtual cohomological dimension
Let Mod_g be the mapping class group of a genus g >= 2 surface. The group Mod_g has virtual cohomological dimension 4g-5. In this note we use a theorem of Broaddus and the combinatorics of chord diagrams to prove that H^{4g-5}(Mod_g; Q) = 0.
\section{Introduction} Let $\Mod_g$ be the mapping class group of a closed, oriented, genus $g\geq 2$ surface, and let ${\mathcal M}_g$ be the moduli space of genus $g$ Riemann surfaces. It is well-known that for each $i\geq 0$ \[H^i(\Mod_g;\Q) \cong H^i({\mathcal M}_g;\Q).\] It is a fundamental open problem to de...
{ "timestamp": "2011-10-07T02:01:33", "yymm": "1108", "arxiv_id": "1108.0622", "language": "en", "url": "https://arxiv.org/abs/1108.0622", "abstract": "Let Mod_g be the mapping class group of a genus g >= 2 surface. The group Mod_g has virtual cohomological dimension 4g-5. In this note we use a theorem of B...
https://arxiv.org/abs/2108.02848
Construction and application of provable positive and exact cubature formulas
Many applications require multi-dimensional numerical integration, often in the form of a cubature formula. These cubature formulas are desired to be positive and exact for certain finite-dimensional function spaces (and weight functions). Although there are several efficient procedures to construct positive and exact ...
\section{Introduction} \label{sec:introduction} Numerical integration is an omnipresent technique in applied mathematics, engineering, and many other sciences. Prominent examples include numerical differential equations \cite{hesthaven2007nodal,quarteroni2008numerical,ames2014numerical}, machine learning \cite{mur...
{ "timestamp": "2021-08-12T02:03:39", "yymm": "2108", "arxiv_id": "2108.02848", "language": "en", "url": "https://arxiv.org/abs/2108.02848", "abstract": "Many applications require multi-dimensional numerical integration, often in the form of a cubature formula. These cubature formulas are desired to be posi...
https://arxiv.org/abs/2106.06878
Probabilistic Group Testing with a Linear Number of Tests
In probabilistic nonadaptive group testing (PGT), we aim to characterize the number of pooled tests necessary to identify a random $k$-sparse vector of defectives with high probability. Recent work has shown that $n$ tests are necessary when $k =\omega(n/\log n)$. It is also known that $O(k \log n)$ tests are necessary...
\section{Introduction} Group testing is a sparse recovery problem where we aim to recover a small set of $k$ ``defective'' items from among $n$ total items using pooled tests. Originally introduced in the context of testing blood samples for diseases where multiple samples can be combined together \cite{dorfman1943det...
{ "timestamp": "2021-06-15T02:17:18", "yymm": "2106", "arxiv_id": "2106.06878", "language": "en", "url": "https://arxiv.org/abs/2106.06878", "abstract": "In probabilistic nonadaptive group testing (PGT), we aim to characterize the number of pooled tests necessary to identify a random $k$-sparse vector of de...
https://arxiv.org/abs/1703.10414
Equivalence between GLT sequences and measurable functions
The theory of Generalized Locally Toeplitz (GLT) sequences of matrices has been developed in order to study the asymptotic behaviour of particular spectral distributions when the dimension of the matrices tends to infinity. A key concepts in this theory are the notion of Approximating Classes of Sequences (a.c.s.), and...
\section{Introduction} When dealing with the discretization of differential equations, we often have to solve sequences of linear equations in the form $A_nx=b_n$, where $A_n\in \mathbb C^{n\times n}$. The dimension of the matrices is determined by the degree of refinement of the mesh used in the Finite Difference me...
{ "timestamp": "2017-03-31T02:05:18", "yymm": "1703", "arxiv_id": "1703.10414", "language": "en", "url": "https://arxiv.org/abs/1703.10414", "abstract": "The theory of Generalized Locally Toeplitz (GLT) sequences of matrices has been developed in order to study the asymptotic behaviour of particular spectra...
https://arxiv.org/abs/1809.00882
An elementary proof of de Finetti's Theorem
A sequence of random variables is called exchangeable if the joint distribution of the sequence is unchanged by any permutation of the indices. De Finetti's theorem characterizes all $\{0,1\}$-valued exchangeable sequences as a "mixture" of sequences of independent random variables. We present an new, elementary proof ...
\section{Introduction} \begin{definition} A finite sequence of (real valued) random variables $X_{1},X_{2},\ldots,X_{N}$ on a probability space $(\Omega,\mathcal{F},\mathbb{P}) $ is called \emph{exchangeable}, if for any permutation $\pi$ of $\{1,2,\ldots,N\}$ the distributions of $X_{\pi(1)},X_{\pi(2)},\ldots,X_...
{ "timestamp": "2018-09-05T02:28:09", "yymm": "1809", "arxiv_id": "1809.00882", "language": "en", "url": "https://arxiv.org/abs/1809.00882", "abstract": "A sequence of random variables is called exchangeable if the joint distribution of the sequence is unchanged by any permutation of the indices. De Finetti...
https://arxiv.org/abs/2112.11770
Poncelet's theorem for conics in any position and any characteristic
Poncelet's theorem states that if there exists an n-sided polygon which is inscribed in a given conic C and circumscribed about another conic D, then there are infinitely many such n-gons. Proofs of this theorem that we are aware of, including Poncelet's original proof and the celebrated modern proof by Griffiths and H...
\subsection*{Notation} Let $\PP^2$ be the projective plane over an algebraically closed field~$k$. Let $p,q\in \PP^2$ be two distinct points, and let $C\subseteq \PP^2$ be a conic. \begin{itemize} \item We write $L(p,q)$ for the line through $p$ and $q$. \item If $p\in C$, we write $T_p\,C$ for the line tangent ...
{ "timestamp": "2021-12-23T02:12:59", "yymm": "2112", "arxiv_id": "2112.11770", "language": "en", "url": "https://arxiv.org/abs/2112.11770", "abstract": "Poncelet's theorem states that if there exists an n-sided polygon which is inscribed in a given conic C and circumscribed about another conic D, then ther...
https://arxiv.org/abs/2212.05739
Spectral extremal graphs for the bowtie
Let $F_k$ be the (friendship) graph obtained from $k$ triangles by sharing a common vertex. The $F_k$-free graphs of order $n$ which attain the maximal spectral radius was firstly characterized by Cioabă, Feng, Tait and Zhang [Electron. J. Combin. 27 (4) (2020)], and later uniquely determined by Zhai, Liu and Xue [Elec...
\section{Introduction} In this paper, we shall use the following standard notation; see, e.g., the monograph \cite{BM2008}. We consider only simple and undirected graphs. Let $G$ be a simple graph with vertex set $V(G)=\{v_1, \ldots, v_n\}$ and edge set $E(G)=\{e_1, \ldots, e_m\}$. We usually write $n$ and $m...
{ "timestamp": "2022-12-13T02:19:40", "yymm": "2212", "arxiv_id": "2212.05739", "language": "en", "url": "https://arxiv.org/abs/2212.05739", "abstract": "Let $F_k$ be the (friendship) graph obtained from $k$ triangles by sharing a common vertex. The $F_k$-free graphs of order $n$ which attain the maximal sp...