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In this paper we provide a geometric condition satisfied by certain closed subsets of the Riemann sphere which implies that their hyperbolic convex hulls in $\mathbb{H}^3$ have infinite volume. As a corollary, we characterize continua in…

Geometric Topology · Mathematics 2026-05-07 Cameron MacMahon

Let $\mathcal{M}_{g,\epsilon}$ be the $\epsilon$-thick part of the moduli space $\mathcal{M}_g$ of closed genus $g$ surfaces. In this article, we show that the number of balls of radius $r$ needed to cover $\mathcal{M}_{g,\epsilon}$ is…

Geometric Topology · Mathematics 2013-01-29 Alastair Fletcher , Jeremy Kahn , Vladimir Markovic

The deviation of a general convex body with twice differentiable boundary and an arbitrarily positioned polytope with a given number of vertices is studied. The paper considers the case where the deviation is measured in terms of the…

Metric Geometry · Mathematics 2018-11-13 Julian Grote , Christoph Thaele , Elisabeth M. Werner

We present a new proof of the sphere covering inequality in the spirit of comparison geometry, and as a byproduct we find another sphere covering inequality which can be viewed as the dual of the original one. We also prove sphere covering…

Analysis of PDEs · Mathematics 2019-01-02 Changfeng Gui , Fengbo Hang , Amir Moradifam

We consider the volume of a Boolean expression of some congruent balls about a given system of centers in the $d$-dimensional Euclidean space. When the radius $r$ of the balls is large, this volume can be approximated by a polynomial of…

Metric Geometry · Mathematics 2017-12-22 Balázs Csikós

We give a sharp lower bound on the area of the domain enclosed by an embedded curve lying on a two-dimensional sphere, provided that geodesic curvature of this curve is bounded from below. Furthermore, we prove some dual inequalities for…

Differential Geometry · Mathematics 2016-05-31 Alexander Borisenko , Kostiantyn Drach

For a finite planar graph, it associates with some metric spaces, called (regular) spherical polyhedral surfaces, by replacing faces with regular spherical polygons in the unit sphere and gluing them edge-to-edge. We consider the class of…

Metric Geometry · Mathematics 2018-05-01 Yohji Akama , Bobo Hua , Yanhui Su

In 2021, Ordentlich, Regev and Weiss made a breakthrough that the lattice covering density of any $n$-dimensional convex body is upper bounded by $cn^{2}$, improving on the best previous bound established by Rogers in 1959. However, for the…

Metric Geometry · Mathematics 2025-06-04 Matthias Schymura , Jun Wang , Fei Xue

In this paper we consider the problem of minimizing the relative perimeter under a volume constraint in the interior of a conically bounded convex set, i.e., an unbounded convex body admitting an \emph{exterior} asymptotic cone. Results…

Differential Geometry · Mathematics 2014-10-15 Manuel Ritoré , Efstratios Vernadakis

The smallest hyperconvex metric space containing a given metric space X is called the tight span of X. It is known that tight spans have many nice geometric and topological properties, and they are gradually becoming a target of research of…

Metric Geometry · Mathematics 2021-12-24 Sunhyuk Lim , Facundo Memoli , Zhengchao Wan , Qingsong Wang , Ling Zhou

Fix an integral Soddy sphere packing P. Let K be the set of all curvatures in P. A number n is called represented if n is in K, that is, if there is a sphere in P with curvature equal to n. A number n is called admissible if it is…

Number Theory · Mathematics 2017-06-16 Alex Kontorovich

We survey results on the problem of covering the space ${\mathbb R}^n$, or a convex body in it, by translates of a convex body. Our main goal is to present a diverse set of methods. A theorem of Rogers is a central result, according to…

Metric Geometry · Mathematics 2016-03-16 Márton Naszódi

We prove sharp inequalities for the average number of affine diameters through the points of a convex body $K$ in ${\mathbb R}^n$. These inequalities hold if $K$ is either a polytope or of dimension two. An example shows that the proof…

Metric Geometry · Mathematics 2014-05-08 Imre Barany , Daniel Hug , Rolf Schneider

We improve the previously best known upper bounds on the sizes of $\theta$-spherical codes for every $\theta<\theta^*\approx 62.997^{\circ}$ at least by a factor of $0.4325$, in sufficiently high dimensions. Furthermore, for sphere packing…

Metric Geometry · Mathematics 2023-10-10 Naser T. Sardari , Masoud Zargar

In this note we examine the volume of the convex hull of two congruent copies of a convex body in Euclidean $n$-space, under some subsets of the isometry group of the space. We prove inequalities for this volume if the two bodies are…

Metric Geometry · Mathematics 2013-06-19 Ákos G. Horváth , Z. Lángi

A metric space is indivisible if for any partition of it into finitely many pieces one piece contains an isometric copy of the whole space. Continuing our investigation of indivisible metric spaces, we show that a countable ultrametric…

Metric Geometry · Mathematics 2007-05-23 Christian Delhommé , Claude Laflamme , Maurice Pouzet , Norbert Sauer

General results on convex bodies are reviewed and used to derive an exact closed-form parametric formula for the boundary of the geometric (Minkowski) sum of $k$ ellipsoids in $n$-dimensional Euclidean space. Previously this was done…

Metric Geometry · Mathematics 2021-07-20 Navid Hashemi , Justin Ruths

General results on convex bodies are reviewed and used to derive an exact closed-form parametric formula for the boundary of the geometric (Minkowski) sum of $k$ ellipsoids in $n$-dimensional Euclidean space. Previously this was done…

Systems and Control · Electrical Eng. & Systems 2021-07-07 Navid Hashemi , Justin Ruths

In this paper we show that a spherical convex body $C$ is of constant diameter $\tau$ if and only if $C$ is of constant width $\tau$, for $0<\tau<\pi$. Moreover, some applications to Wulff shapes are given.

Metric Geometry · Mathematics 2019-12-18 Huhe Han , Denghui Wu

The problem of bounding of the distance between the two bodies of volume $\varepsilon$ located inside the $n$-dimensional body $B$ of unit volume where $n \to \infty$ is considered. In some cases such distances are bounded by function…

Metric Geometry · Mathematics 2014-12-24 Fyodor Ivlev