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We prove several exact quantitative versions of Helly's and Tverberg's theorems, which guarantee that a finite family of convex sets in $R^d$ has a large intersection. Our results characterize conditions that are sufficient for the…

Combinatorics · Mathematics 2020-05-05 Sherry Sarkar , Alexander Xue , Pablo Soberón

Neglecting many motivating details for the Park-Pham theorem (previously known as the Kahn-Kalai conjecture), the result starts with a finite set $X$, a non-trivial upper set $\mathcal{F} \subseteq 2^X$, and a particular parameterized…

Combinatorics · Mathematics 2024-08-16 Bryce Alan Christopherson , Darian Colgrove

Take a set of balls in $\mathbb R^d$. We find a subset of pairwise disjoint balls whose combined perimeter controls the perimeter of the union of the original balls. This can be seen as a boundary version of the Vitali covering lemma. We…

Classical Analysis and ODEs · Mathematics 2025-07-22 Julian Weigt

In this survey, we discuss volumetric and combinatorial results concerning (mostly finite) intersections or unions of balls (mostly of equal radii) in the $d$-dimensional real vector space, mostly equipped with the Euclidean norm. Our first…

Metric Geometry · Mathematics 2025-12-30 Károly Bezdek , Zsolt Lángi , Márton Naszódi

In the concluding remarks of their 1993 published and now famous paper, Jeff Kahn and Gil Kalai wrote in particular: "Our construction shows that Borsuk's conjecture is false for d = 1,325 and for every d > 2,014." But, as Bernulf Weiszbach…

Combinatorics · Mathematics 2018-10-12 Thomas Jenrich

This paper explores some sufficient conditions for the enhanced solvability of strong vector equilibrium problems, which can be established via a variational approach. Enhanced solvability here means existence of solutions, which are strong…

Optimization and Control · Mathematics 2022-05-11 Amos Uderzo

A random intersection graph is constructed by independently assigning a subset of a given set of objects $W,$ to each vertex of the vertex set $V$ of a simple graph $G.$ There is an edge between two vertices of $V,$ iff their respective…

Probability · Mathematics 2008-09-09 Bhupendra Gupta

We introduce a new generalization of relative entropy to non-negative vectors with sums $\gt 1$. We show in a purely combinatorial setting, with no probabilistic considerations, that in the presence of linear constraints defining a convex…

Information Theory · Computer Science 2024-05-08 Kostas N. Oikonomou

The classical Erd\H{o}s-Ko-Rado theorem on the size of an intersecting family of $k$-subsets of the set $[n] = \{1, 2, \dots, n\}$ is one of the fundamental intersection theorems for set systems. After the establishment of the EKR theorem,…

Combinatorics · Mathematics 2024-03-08 Jiuqiang Liu , Guihai Yu , Lihua Feng , Yongjiang Wu

Assuming a lower bound on the dimension, we prove a long standing conjecture concerning the classification of global solutions of the obstacle problem with unbounded coincidence sets.

Analysis of PDEs · Mathematics 2022-08-08 Simon Eberle , Henrik Shahgholian , Georg S. Weiss

We show that in $\mathbb{R}^d$ there are purely unrectifiable sets of Hausdorff (and even box counting) dimension $d-1$ which are not tube null, settling a question of Carbery, Soria and Vargas, and improving a number of results by the same…

Classical Analysis and ODEs · Mathematics 2015-11-06 Pablo Shmerkin , Ville Suomala

The best merge problem in industrial data science generates instances where disparate data sources place incompatible relational structures on the same set $V$ of objects. Graph vertex labelling data may include (1) missing or erroneous…

Combinatorics · Mathematics 2018-09-25 R. W. R. Darling , David G. Harris , Dev R. Phulara , John A. Proos

A real vector space combined with an inverse for vectors is sufficient to define a vector continued fraction whose parameters consist of vector shifts and changes of scale. The choice of sign for different components of the vector inverse…

Mathematical Physics · Physics 2009-11-10 Roger Haydock , C. M. M. Nex , Geoffrey Wexler

In this paper, we provide a common generalization to the well-known Erd\H{o}s-Ko-Rado Theorem, Frankl-Wilson Theorem, Alon-Babai-Suzuki Theorem, and Snevily Theorem on set systems with $\mathcal{L}$-intersections. As a consequence, we…

Combinatorics · Mathematics 2017-07-07 Jiuqiang Liu , Shenggui Zhang , Jimeng Xiao

Let $[n]$ (resp. $V$) be an $n$-element set (resp. $n$-dimensional vector space over the finite field $\mathbb{F}_{q}$), and $\binom{[n]}{k}$ (resp. $\genfrac{[}{]}{0pt}{}{V}{k}$) denote the set of all $k$-subsets of $[n]$ (resp.…

Combinatorics · Mathematics 2026-05-25 Shuhui Yu , Lijun Ji

We bound the number of incidences between points and spheres in finite vector spaces by bounding the sum of the number of points in the pairwise intersections of the spheres. We obtain new incidence bounds that are interesting when the…

Combinatorics · Mathematics 2025-10-01 Doowon Koh , Ben Lund , Chuandong Xu , Semin Yoo

In this article, we study several aspects of the intersections of algorithmically random closed sets. First, we answer a question of Cenzer and Weber, showing that the operation of intersecting relatively random closed sets (with respect to…

Logic · Mathematics 2021-03-09 Adam Case , Christopher P. Porter

In this work, we study the generalized sorting problem, where we are given a set of $n$ elements to be sorted, but only a subset of all possible pairwise element comparisons is allowed. We look at the problem from the perspective of the…

Data Structures and Algorithms · Computer Science 2025-09-04 A. Manas

We conjecture new uncertainty relations which restrict correlations between results of measurements performed by two separated parties on a shared quantum state. The first uncertainty relation bounds the sum of two mutual informations when…

We give a brief discussion of the recently developed Constrained-Path Monte Carlo Method. This method is a quantum Monte Carlo technique that eliminates the fermion sign problem plaguing simulations of systems of interacting electrons. The…

Strongly Correlated Electrons · Physics 2009-10-31 J. E. Gubernatis , M. Guerrero