Estimates for certain Orlicz–Sobolev capacities of an Euclidean ball

2010 ◽  
Vol 72 (11) ◽  
pp. 4316-4330 ◽  
Author(s):  
Jani Joensuu
Keyword(s):  
1996 ◽  
Vol 13 (4) ◽  
pp. 585-610 ◽  
Author(s):  
J S Dowker
Keyword(s):  

2009 ◽  
Vol 19 (05) ◽  
pp. 389-414 ◽  
Author(s):  
FRANK NIELSEN ◽  
RICHARD NOCK

In this paper, we first survey prior work for computing exactly or approximately the smallest enclosing balls of point or ball sets in Euclidean spaces. We classify previous work into three categories: (1) purely combinatorial, (2) purely numerical, and (3) recent mixed hybrid algorithms based on coresets. We then describe two novel tailored algorithms for computing arbitrary close approximations of the smallest enclosing Euclidean ball. These deterministic heuristics are based on solving relaxed decision problems using a primal-dual method. The primal-dual method is interpreted geometrically as solving for a minimum covering set, or dually as seeking for a minimum piercing set. Finally, we present some applications in machine learning of the exact and approximate smallest enclosing ball procedure, and discuss about its extension to non-Euclidean information-theoretic spaces.


Author(s):  
Changwei Xiong

Abstract We consider an $n$-dimensional smooth Riemannian manifold $M^n=[0,R)\times \mathbb{S}^{n-1}$ endowed with a warped product metric $g=dr^2+h^2(r)g_{\mathbb{S}^{n-1}}$ and diffeomorphic to a Euclidean ball. Suppose that $M$ has strictly convex boundary. First, for the classical Steklov eigenvalue problem, we derive an optimal lower (upper, respectively) bound for its eigenvalue gaps in terms of $h^{\prime}(R)/h(R)$ when $n\geq 2$ and $Ric_g\geq 0$ ($\leq 0$, respectively). Second, in the same spirit, for two 4th-order Steklov eigenvalue problems studied by Kuttler and Sigillito in 1968, we deduce an optimal lower bound for their eigenvalue gaps in terms of either $h^{\prime}(R)/h^3(R)$ or $h^{\prime}(R)/h(R)$ when $n=2$ and the Gaussian curvature is nonnegative. We also consider optimal estimates on the eigenvalue ratios for these eigenvalue problems.


2018 ◽  
Vol 372 (1-2) ◽  
pp. 179-187 ◽  
Author(s):  
Ezequiel Barbosa
Keyword(s):  

2012 ◽  
Vol 55 (3) ◽  
pp. 498-508 ◽  
Author(s):  
Matthieu Fradelizi ◽  
Grigoris Paouris ◽  
Carsten Schütt

AbstractWe establish some inequalities for the second momentof a convex body K under various assumptions on the position of K.


2020 ◽  
Vol 54 (7) ◽  
pp. 601-614
Author(s):  
M. V. Nevskii ◽  
A. Yu. Ukhalov

2003 ◽  
Vol 35 (02) ◽  
pp. 303-318 ◽  
Author(s):  
Maria Deijfen

A continuum growth model is introduced. The state at time t, S t , is a subset of ℝ d and consists of a connected union of randomly sized Euclidean balls, which emerge from outbursts at their centre points. An outburst occurs somewhere in S t after an exponentially distributed time with expected value |S t |-1 and the location of the outburst is uniformly distributed over S t . The main result is that, if the distribution of the radii of the outburst balls has bounded support, then S t grows linearly and S t /t has a nonrandom shape as t → ∞. Due to rotational invariance the asymptotic shape must be a Euclidean ball.


2015 ◽  
Vol 67 (1) ◽  
pp. 3-27
Author(s):  
M. Angeles Alfonseca ◽  
Jaegil Kim

AbstractOne of the fundamental results in convex geometry is Busemann's theorem, which states that the intersection body of a symmetric convex body is convex. Thus, it is only natural to ask if there is a quantitative version of Busemann's theorem, i.e., if the intersection body operation actually improves convexity. In this paper we concentrate on the symmetric bodies of revolution to provide several results on the (strict) improvement of convexity under the intersection body operation. It is shown that the intersection body of a symmetric convex body of revolution has the same asymptotic behavior near the equator as the Euclidean ball. We apply this result to show that in sufficiently high dimension the double intersection body of a symmetric convex body of revolution is very close to an ellipsoid in the Banach–Mazur distance. We also prove results on the local convexity at the equator of intersection bodies in the class of star bodies of revolution.


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