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We classify $\mathcal{R}$- and $\mathcal{L}$-cross-sections of partial wreath product of inverse semigroups. As a corollary, we get the description of $\mathcal{R}$- and $\mathcal{L}$-cross-sections of the semigroupof partial automorphisms…

Group Theory · Mathematics 2020-06-30 Eugenia Kochubinska

We give a local classification of generalized complex structures. About a point, a generalized complex structure is equivalent to a product of a symplectic manifold with a holomorphic Poisson manifold. We use a Nash-Moser type argument in…

Differential Geometry · Mathematics 2013-08-06 Michael Bailey

Over some types of trees with a given number of vertices, which trees minimize or maximize the total number of subtrees or leaf containing subtrees are studied. Here are some of the main results:\ (1)\, Sharp upper bound on the total number…

Combinatorics · Mathematics 2012-06-15 Shuchao Li , Shujing Wang

Given a Borel class of trees, we show that there is a tree in that class whose Scott sentence is not too much more complicated than the definition of the class. In particular, if the class is definable by a $\Pi_\alpha$ sentence, then there…

Logic · Mathematics 2026-02-23 Matthew Harrison-Trainor , J. Thomas Kim

We determine the rank of a random matrix over an arbitrary field with prescribed numbers of non-zero entries in each row and column. As an application we obtain a formula for the rate of low-density parity check codes. This formula…

Combinatorics · Mathematics 2024-06-21 Amin Coja-Oghlan , Alperen A. Ergür , Pu Gao , Samuel Hetterich , Maurice Rolvien

We prove general fomulas for the deviations of two overpartition ranks from the average. These formulas are in terms of Appell--Lerch series and sums of quotients of theta functions and can be used, among other things, to recover any of the…

Number Theory · Mathematics 2025-07-14 Jeremy Lovejoy , Robert Osburn

We introduce the notion of the definable rank of an ordered field, ordered abelian group and ordered set, respectively. We study the relation between the definable rank of an ordered field and the definable rank of the value group of its…

Logic · Mathematics 2026-01-13 Lothar Sebastian Krapp , Salma Kuhlmann , Lasse Vogel

We generalize the results from [X.-D. Zhang, X.-P. Lv, Y.-H. Chen, \textit{Ordering trees by the Laplacian coefficients}, Linear Algebra Appl. (2009), doi:10.1016/j.laa.2009.04.018] on the partial ordering of trees with given diameter. For…

Combinatorics · Mathematics 2015-03-19 Aleksandar Ili\' c

We construct a model category (in the sense of Quillen) for set theory, starting from two arbitrary, but natural, conventions. It is the simplest category satisfying our conventions and modelling the notions of finiteness, countability and…

Logic · Mathematics 2013-05-29 Assaf Hasson , Misha Gavrilovich

We consider an elliptic surface $\pi: \mathcal{E}\rightarrow \mathbb{P}^1$ defined over a number field $k$ and study the problem of comparing the rank of the special fibres over $k$ with that of the generic fibre over $k(\mathbb{P}^1)$. We…

Number Theory · Mathematics 2013-07-24 Cecilia Salgado

It implicitly follows from the work of [Colbourn, El-Mallah: On two dual classes of planar graphs. Discrete Mathematics 80(1): 21-40 (1990)] that every planar partial 3-tree is a subgraph of a planar 3-tree. This fact has already enabled to…

Discrete Mathematics · Computer Science 2012-10-31 Jan Kratochvíl , Michal Vaner

In this paper, we analyze and compare three of the many algebraic structures that have been used for modeling dependent type theories: categories with families, split type-categories, and representable maps of presheaves. We study these in…

Logic · Mathematics 2023-06-22 Benedikt Ahrens , Peter LeFanu Lumsdaine , Vladimir Voevodsky

In "Faces of a Hyperplane Arrangement Enumerated by Ideal Dimension, with Applications to Plane, Plaids, and Shi," Zaslavsky showed how to compute the number $r_\ell(\mathcal{A})$ of regions of a real hyperplane arrangement $\mathcal{A}$…

Combinatorics · Mathematics 2026-05-21 Finn Southerland , Lani Southern , Su Zhou

Suppose $X$ is a smooth quasiprojective variety over $\cc$ and $\rho : \pi _1(X,x) \to SL(2,\cc)$ is a Zariski-dense representation with quasiunipotent monodromy at infinity. Then $\rho$ factors through a map $X\to Y$ with $Y$ either a…

Algebraic Geometry · Mathematics 2014-01-14 Kevin Corlette , Carlos T. Simpson

Skew lattices are non-commutative generalizations of lattices. The coset structure decomposition is an original approach to the study of these algebras describing the relation between its rectangular classes. In this paper we will look at…

Rings and Algebras · Mathematics 2014-07-10 Joao Pita Costa

We present a physically-inspired model and an efficient algorithm to infer hierarchical rankings of nodes in directed networks. It assigns real-valued ranks to nodes rather than simply ordinal ranks, and it formalizes the assumption that…

Physics and Society · Physics 2018-06-14 Caterina De Bacco , Daniel B. Larremore , Cristopher Moore

In recent years, saliency ranking has emerged as a challenging task focusing on assessing the degree of saliency at instance-level. Being subjective, even humans struggle to identify the precise order of all salient instances. Previous…

Computer Vision and Pattern Recognition · Computer Science 2023-08-02 Chengxiao Sun , Yan Xu , Jialun Pei , Haopeng Fang , He Tang

Based on decision trees, many fields have arguably made tremendous progress in recent years. In simple words, decision trees use the strategy of "divide-and-conquer" to divide the complex problem on the dependency between input features and…

Machine Learning · Computer Science 2021-01-22 Jinxiong Zhang

We present a unification and generalization of what is known in the literature as sequentially and hierarchically semi-separable (SSS and HSS) representations for matrices. Describing rank-structured representations of (inverses of) sparse…

Numerical Analysis · Mathematics 2024-08-12 Nithin Govindarajan , Shivkumar Chandrasekaran , Patrick Dewilde

We show that the quantifier elimination result for the Shelah-Spencer almost sure theories of sparse random graphs $G(n,n^{-\alpha})$ given by Laskowski in $[7]$ extends to their various analogues. The analogues will be obtained as theories…

Logic · Mathematics 2018-07-17 Danul K. Gunatilleka
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