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Let $L \subset {\Bbb R}^3$ be the union of unit balls, whose centres lie on the $z$-axis, and are equidistant with distance $2d \in [2, 2\sqrt{2}]$. Then a packing of unit balls in ${\Bbb R}^3$ consisting of translates of $L$ has a density…

Metric Geometry · Mathematics 2017-06-19 K. Böröczky , A. Heppes , E. Makai

In this paper we will discuss optimal lower and upper density of non-parallel cylinder packings in $R^{3}$ and similar problems. The main result of the paper is a proof of the conjecture of K. Kuperberg for upper density (existence of a…

Metric Geometry · Mathematics 2023-10-12 Ofek Eliyahu

The aim of this paper is to study lattice-like coverings with congruent translation balls and the packings and coverings with a type of translation cylinders in Sol space related to the fundamental lattices. We introduce the notions of the…

Metric Geometry · Mathematics 2025-12-04 Judit Sajtos , Jenő Szirmai

The Kepler conjecture asserts that the density of a packing of congruent balls in three dimensions is never greater than $\pi/\sqrt{18}$. A computer assisted verification confirmed this conjecture in 1998. This article gives a historical…

Metric Geometry · Mathematics 2007-05-23 Thomas C. Hales

This is the second in a series of papers giving a proof of the Kepler conjecture, which asserts that the density of a packing of congruent spheres in three dimensions is never greater than $\pi/\sqrt{18}\approx 0.74048...$. This is the…

Metric Geometry · Mathematics 2007-05-23 Samuel P. Ferguson , Thomas C. Hales

The present work surveys problems in $n$-dimensional space with $n$ large. Early development in the study of packing and covering in high dimensions was motivated by the geometry of numbers. Subsequent results, such as the discovery of the…

Metric Geometry · Mathematics 2022-02-24 Gábor Fejes Tóth

This is the eighth and final paper in a series giving a proof of the Kepler conjecture, which asserts that the density of a packing of congruent spheres in three dimensions is never greater than $\pi/\sqrt{18}\approx 0.74048...$. This is…

Metric Geometry · Mathematics 2007-05-23 Thomas C. Hales

This is the sixth in a series of papers giving a proof of the Kepler conjecture, which asserts that the density of a packing of congruent spheres in three dimensions is never greater than $\pi/\sqrt{18}\approx 0.74048...$. This is the…

Metric Geometry · Mathematics 2007-05-23 Thomas C. Hales

Determining the minimum density of a covering of $\mathbb{R}^{n}$ by Euclidean unit balls as $n\to\infty$ is a major open problem, with the best known results being the lower bound of $\left(\mathrm{e}^{-3/2}+o(1)\right)n$ by Coxeter, Few…

Combinatorics · Mathematics 2025-10-30 Boris Bukh , Jun Gao , Xizhi Liu , Oleg Pikhurko , Shumin Sun

Dense packings have served as useful models of the structure of liquid, glassy and crystal states of matter, granular media, heterogeneous materials, and biological systems. Probing the symmetries and other mathematical properties of the…

Statistical Mechanics · Physics 2015-05-14 S. Torquato , Y. Jiao

We use computational experiments to find the rectangles of minimum area into which a given number n of non-overlapping congruent circles can be packed. No assumption is made on the shape of the rectangles. Most of the packings found have…

Metric Geometry · Mathematics 2007-05-23 Boris D. Lubachevsky , Ronald Graham

This paper provides the currently best known upper bound on the density of a packing in three-dimensional Euclidean space of two types of spheres whose size ratio is the largest one that allows the insertion of a small sphere in each…

Metric Geometry · Mathematics 2025-05-21 Thomas Fernique , Daria Pchelina

We give upper bounds for the density of unit ball packings relative to their outer parallel domains and discuss their connection to contact numbers. Also, packings of soft balls are introduced and upper bounds are given for the fraction of…

Metric Geometry · Mathematics 2015-11-24 Karoly Bezdek , Zsolt Langi

We construct a dense packing of regular tetrahedra, with packing density $D > >.7786157$.

Metric Geometry · Mathematics 2010-01-05 Elizabeth R. Chen

Motivated by modern applications like image processing and wireless sensor networks, we consider a variation of the famous Kepler Conjecture. Given any infinite set of unit balls covering the whole space, we want to know the optimal (lim…

General Mathematics · Mathematics 2007-12-20 Binhai Zhu

We present the densest known packing of regular tetrahedra with density phi = 4000/4671 = 0.856347... Like the recently discovered packings of Kallus et al. [arXiv:0910.5226] and Torquato-Jiao [arXiv:0912.4210], our packing is crystalline…

Statistical Mechanics · Physics 2010-07-27 Elizabeth R. Chen , Michael Engel , Sharon C. Glotzer

This is the first in a series of papers giving a proof of the Kepler conjecture, which asserts that the density of a packing of congruent spheres in three dimensions is never greater than $\pi/\sqrt{18}\approx 0.74048...$. This is the…

Metric Geometry · Mathematics 2007-05-23 Thomas C. Hales

We analyze the general problem of determining optimally dense packings, in a Euclidean or hyperbolic space, of congruent copies of some fixed finite set of bodies. We are strongly guided by examples of aperiodic tilings in Euclidean space…

Metric Geometry · Mathematics 2018-07-11 Lewis Bowen , Charles Holton , Charles Radin , Lorenzo Sadun

The Kepler conjecture asserts that no packing of congruent balls in three-dimensional Euclidean space has density greater than that of the face-centered cubic packing. The original proof, announced in 1998 and published in 2006, is long and…

Metric Geometry · Mathematics 2009-02-03 Thomas C. Hales , John Harrison , Sean McLaughlin , Tobias Nipkow , Steven Obua , Roland Zumkeller

We prove upper bounds on the average kissing number $k(\mathcal{P})$ and contact number $C(\mathcal{P})$ of an arbitrary finite non-congruent sphere packing $\mathcal{P}$, and prove an upper bound on the packing density…

Metric Geometry · Mathematics 2015-10-05 Samuel Reid