2,345 research outputs found
Density bounds for outer parallel domains of unit ball packings
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 space covered by them.Comment: 22 pages, 1 figur
Periodicity and Circle Packing in the Hyperbolic Plane
We prove that given a fixed radius , the set of isometry-invariant
probability measures supported on ``periodic'' radius -circle packings of
the hyperbolic plane is dense in the space of all isometry-invariant
probability measures on the space of radius -circle packings. By a periodic
packing, we mean one with cofinite symmetry group. As a corollary, we prove the
maximum density achieved by isometry-invariant probability measures on a space
of radius -packings of the hyperbolic plane is the supremum of densities of
periodic packings. We also show that the maximum density function varies
continuously with radius.Comment: 25 page
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
On contact numbers of totally separable unit sphere packings
Contact numbers are natural extensions of kissing numbers. In this paper we
give estimates for the number of contacts in a totally separable packing of n
unit balls in Euclidean d-space for all n>1 and d>1.Comment: 11 page
Sphere packings II
An earlier paper describes a program to prove the Kepler conjecture on sphere
packings. This paper carries out the second step of that program. A sphere
packing leads to a decomposition of into polyhedra. The polyhedra are
divided into two classes. The first class of polyhedra, called quasi-regular
tetrahedra, have density at most that of a regular tetrahedron. The polyhedra
in the remaining class have density at most that of a regular octahedron (about
0.7209).Comment: 18 pages. Second of two older papers in the series on the proof of
the Kepler conjecture. See math.MG/9811071. The original abstract is
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