On a strong version of the Kepler conjecture

We raise and investigate the following problem that one can regard as a very close relative of the densest sphere packing problem. If the Euclidean 3-space is partitioned into convex cells each containing a unit ball, how should the shapes of the cells be designed to minimize the average surface area of the cells? In particular, we prove that the average surface area in question is always at least 13.8564... .Comment: 9 page

Sphere packings revisited

AbstractIn this paper we survey most of the recent and often surprising results on packings of congruent spheres in d-dimensional spaces of constant curvature. The topics discussed are as follows:–Hadwiger numbers of convex bodies and kissing numbers of spheres;–touching numbers of convex bodies;–Newton numbers of convex bodies;–one-sided Hadwiger and kissing numbers;–contact graphs of finite packings and the combinatorial Kepler problem;–isoperimetric problems for Voronoi cells, the strong dodecahedral conjecture and the truncated octahedral conjecture;–the strong Kepler conjecture;–bounds on the density of sphere packings in higher dimensions;–solidity and uniform stability.Each topic is discussed in details along with some of the “most wanted” research problems

On the X-ray number of almost smooth convex bodies and of convex bodies of constant width

The X-ray numbers of some classes of convex bodies are investigated. In particular, we give a proof of the X-ray Conjecture as well as of the Illumination Conjecture for almost smooth convex bodies of any dimension and for convex bodies of constant width of dimensions 3, 4, 5 and 6

On contact graphs of totally separable packings in low dimensions

The contact graph of a packing of translates of a convex body in Euclidean d-space E-d is the simple graph whose vertices are the members of the packing, and whose two vertices are connected by an edge if the two members touch each other. A packing of translates of a convex body is called totally separable, if any two members can be separated by a hyperplane in E-d disjoint from the interior of every packing element. We give upper bounds on the maximum degree (called separable Hadwiger number) and the maximum number of edges (called separable contact number) of the contact graph of a totally separable packing of n translates of an arbitrary smooth convex body in E-d with d = 2, 3, 4. In the proofs, linear algebraic and convexity methods are combined with volumetric and packing density estimates based on the underlying isoperimetric (resp., reverse isoperimetric) inequality. (C) 2018 Elsevier Inc. All rights reserved

From spherical to Euclidean illumination

In this note we introduce the problem of illumination of convex bodies in spherical spaces and solve it for a large subfamily of convex bodies.We derive from it a combinatorial version of the classical illumination problem for convex bodies in Euclidean spaces as well as a solution to that for a large subfamily of convex bodies, which in dimension three leads to special Koebe polyhedra