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In this paper, we consider the isoperimetric problem in the space $\mathbb{R}^N$ with density. Our result states that, if the density f is l.s.c. and converges to a positive limit at infinity, being smaller than this limit far from the…

Analysis of PDEs · Mathematics 2014-11-20 Guido De Philippis , Giovanni Franzina , Aldo Pratelli

We show that at least 1/3 of positive real numbers are in the set of limit points of normalized prime gaps. More precisely, if $p_n$ denotes the $n$th prime and $\mathbb{L}$ is the set of limit points of the sequence $\{(p_{n+1}-p_n)/\log…

Number Theory · Mathematics 2021-03-03 Jori Merikoski

Let $A \subset \mathbb{Z}^d$ be a finite set. It is known that $NA$ has a particular size ($\vert NA\vert = P_A(N)$ for some $P_A(X) \in \mathbb{Q}[X]$) and structure (all of the lattice points in a cone other than certain exceptional…

Combinatorics · Mathematics 2023-07-18 Andrew Granville , George Shakan , Aled Walker

We consider a closed convex set $C$ in a separable, infinite-dimensional Hilbert space and endow the set $\mathcal{N}(C)$ of nonexpansive self-mappings on $C$ with the topology of pointwise convergence. We introduce the notion of a somewhat…

Functional Analysis · Mathematics 2025-08-18 Davide Ravasini , Daylen K. Thimm

Combinatorics on multisets is used to deduce new upper and lower bounds on the number of numerical semigroups of each given genus, significantly improving existing ones. In particular, it is proved that the number $n_g$ of numerical…

Combinatorics · Mathematics 2008-02-18 Maria Bras-Amoros

We define possibly unsaturated, upper semicontinuous Fell bundles over Hausdorff, locally compact groupoids and establish a universal property for representations of their full section C*-algebras on Hilbert modules over arbitrary…

Operator Algebras · Mathematics 2026-04-07 Alcides Buss , Rohit Holkar , Ralf Meyer

It was recently shown that charged AdS boson stars can reproduce the universal structure of the lowest scaling dimension in the subsector of a CFT with fixed large global $U(1)$ charge $Q$. Using the model consisting of Einstein-Maxwell…

High Energy Physics - Theory · Physics 2021-04-23 Shi-Fa Guo , Hai-Shan Liu , H. Lu , Yi Pang

We introduce a new natural notion of convergence for permutations at any specified scale, in terms of the density of patterns of restricted width. In this setting we prove that limits may be chosen independently at a countably infinite…

Combinatorics · Mathematics 2021-10-20 David Bevan

We give improved lower bounds on the size of Kakeya and Nikodym sets over $\mathbb{F}_q^3$. We also propose a natural conjecture on the minimum number of points in the union of a not-too-flat set of lines in $\mathbb{F}_q^3$, and show that…

Combinatorics · Mathematics 2019-03-06 Ben Lund , Shubhangi Saraf , Charles Wolf

The $F$-theorem states that in three dimensions the sphere free energy of a field theory must decrease between ultraviolet and infrared fixed points of the renormalization group flow, and it has been proven for unitary conformal field…

High Energy Physics - Theory · Physics 2022-06-16 Dario Benedetti , Razvan Gurau , Sabine Harribey , Davide Lettera

We show there is an upper bound on the diameter of a closed, hyperbolic 3-manifold in terms of the length of any presentation of its fundamental group.

Geometric Topology · Mathematics 2007-05-23 Matthew E. White

Let $F$ be a finite field with characteristic greater than two. Define a \emph{Besicovitch set} in $F^4$ to be a set $P \subseteq F^4$ containing a line in every direction. The \emph{Kakeya conjecture} asserts that $|P| \approx |F|^4$. A…

Classical Analysis and ODEs · Mathematics 2007-05-23 Terence Tao

A family of sets is union-closed (UC) if the union of any two sets in the family is also in the family. Frankl's UC sets conjecture states that for any nonempty UC family $\mathcal{F} \subseteq 2^{[n]}$ such that $\mathcal{F} \neq…

Combinatorics · Mathematics 2019-03-07 Jonad Pulaj

Talagrand conjectured that if a family of sets $\mathcal{F}$ over $X = \{ 1,2,\cdots, N \}$ is of large measure, then constant times of unions of sets in $\mathcal{F}$ will cover a large portion of the power set of $X$. This conjecture is a…

Combinatorics · Mathematics 2025-12-08 Xuan Fang , Tianyu Wang

New bounds on the cardinality of permutation codes equipped with the Ulam distance are presented. First, an integer-programming upper bound is derived, which improves on the Singleton-type upper bound in the literature for some lengths.…

Information Theory · Computer Science 2015-04-21 Faruk Göloğlu , Jüri Lember , Ago-Erik Riet , Vitaly Skachek

Let $A^2(D)$ be the Bergman space over the open unit disk $D$ in the complex plane. Korenblum conjectured that there is an absolute constant $c \in (0,1)$ such that whenever $|f(z)|\le |g(z)|$ in the annulus $c<|z|<1$ then $||f(z)|| \le…

Complex Variables · Mathematics 2015-05-13 Chun-Yen Shen

We prove that for any $\epsilon>0$ and any trigonometric polynomial $f$ with frequencies in the set $\{n^3: N \leq n\leq N+N^{2/3-\epsilon}\}$, one has $$ \|f\|_4 \ll \epsilon^{-1/4}\|f\|_2 $$ with implied constant being absolute. We also…

Classical Analysis and ODEs · Mathematics 2024-03-12 Mikhail R. Gabdullin , Sergei V. Konyagin

We show that the existence of a universal structure implies the existence of a generic structure for any approximable class $\mathcal{C}$ of countable structures. We also show that the converse is not true. As a consequence, we provide…

Logic · Mathematics 2022-06-23 Aristotelis Panagiotopoulos , Katrin Tent

We show that $C(X)$ admits an equivalent pointwise lower semicontinuous locally uniformly rotund norm provided $X$ is Fedorchuk compact of spectral height 3. In other words $X$ admits a fully closed map $f$ onto a metric compact $Y$ such…

Functional Analysis · Mathematics 2018-11-26 S. P. Gul'ko , A. V. Ivanov , M. S. Shulikina , S. Troyanski

We give some explicit upper bounds on the effective birationality of the canonical or anti-canonical system for a singular surface. In particular, we show that for any surface $X$ with $\epsilon$-lc singularity and the canonical divisor…

Algebraic Geometry · Mathematics 2025-08-26 Pinxian Bie