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We study a long standing open problem by Ulam, which is whether the Euclidean ball is the unique body of uniform density which will float in equilibrium in any direction. We answer this problem in the class of origin symmetric n-dimensional…

Metric Geometry · Mathematics 2020-12-15 D. I. Florentin , C. Schuett , E. M. Werner , N. Zhang

We prove a randomized version of the generalized Urysohn inequality relating mean-width to the other intrinsic volumes. To do this, we introduce a stochastic approximation procedure that sees each convex body K as the limit of intersections…

Metric Geometry · Mathematics 2016-06-30 Grigoris Paouris , Peter Pivovarov

In this paper we consider a partial overdetermined mixed boundary value problem in domains inside a cone as in [18]. We show that in cones having an isoperimetric property the only domains which admit a solution and which minimize a…

Analysis of PDEs · Mathematics 2019-05-27 Filomena Pacella , Giulio Tralli

Given a closed subset $\La$ of the open unit ball $B_1\subset \real^n$, $n \geq 3$, we will consider a complete Riemannian metric $g$ on $\bar{B_1} \setminus \La$ of constant scalar curvature equal to $n(n-1)$ and conformally related to the…

Differential Geometry · Mathematics 2007-11-09 Marcos P. Cavalcante

We prove that, among weighted isotropic perimeters, only constant multiples of the Euclidean perimeter satisfy the monotonicity property on nested convex bodies. Although the analogous result fails for general weighted anisotropic…

Metric Geometry · Mathematics 2024-04-09 Giorgio Saracco , Giorgio Stefani

Primal and dual algorithms are developed for solving the $n$-dimensional convex optimization problem of finding the Euclidean ball of minimum radius that covers $m$ given Euclidean balls, each with a given center and radius. Each algorithm…

Optimization and Control · Mathematics 2020-01-16 P. M. Dearing , Mark Cawood

The ball-constrained weighted maximin dispersion problem $(\rm P_{ball})$ is to find a point in an $n$-dimensional Euclidean ball such that the minimum of the weighted Euclidean distance from given $m$ points is maximized. We propose a new…

Optimization and Control · Mathematics 2016-04-11 Shu Wang , Yong Xia

The Illumination Problem may be phrased as the problem of covering a convex body in Euclidean $n$-space by a minimum number of translates of its interior. By a probabilistic argument, we show that, arbitrarily close to the Euclidean ball,…

Metric Geometry · Mathematics 2016-02-24 Márton Naszódi

We consider the class of $\lambda$-concave bodies in $\mathbb R^{n+1}$; that is, convex bodies with the property that each of their boundary points supports a tangent ball of radius $1/\lambda$ that lies locally (around the boundary point)…

Differential Geometry · Mathematics 2019-07-22 Roman Chernov , Kostiantyn Drach , Kateryna Tatarko

In this paper we study the class of so called `ball-bodies' in ${\mathbb R}^n$, given by intersections of translates of Euclidean unit balls (or, equivalently, summand of the Euclidean ball). We study the class along with the natural…

Metric Geometry · Mathematics 2025-05-20 Shiri Artstein-Avidan , Dan I. Florentin

In this survey, we discuss volumetric and combinatorial results concerning (mostly finite) intersections or unions of balls (mostly of equal radii) in the $d$-dimensional real vector space, mostly equipped with the Euclidean norm. Our first…

Metric Geometry · Mathematics 2025-12-30 Károly Bezdek , Zsolt Lángi , Márton Naszódi

In Euclidean space $\mathbb{R}^n$, the minimization problem of a nonlocal isoperimetric functional with a competition between perimeter and a nonlocal term derived from the negative power of the distance function, has been extensively…

Analysis of PDEs · Mathematics 2026-01-29 Haizhong Li , Bo Yang

We study isoperimetric problems modeled on the liquid drop model, with nonlocal interactions under a volume constraint. While balls are natural critical points, we show that, for an unbounded sequence of radii, non-spherical solutions…

Analysis of PDEs · Mathematics 2026-04-22 Fabio De Regibus , Massimo Grossi , Monica Musso

Methodology is provided towards the solution of the minimum enclosing ball problem. This problem concerns the determination of the unique spherical surface of smallest radius enclosing a given bounded set in the d-dimensional Euclidean…

Computational Geometry · Computer Science 2024-10-16 Michael N. Vrahatis

We show that, the solutions of the isoperimetric problem for small volumes are $C^{2,\alpha}$-close to small spheres. On the way, we define a class of submanifolds called pseudo balls, defined by an equation weaker than constancy of mean…

Differential Geometry · Mathematics 2015-05-21 Stefano Nardulli

We consider the variational problem of minimizing an anisotropic perimeter functional under a volume constraint in a Euclidean convex domain. We extend to this setting analytical properties of the isoperimetric profile, topological features…

Differential Geometry · Mathematics 2025-04-14 César Rosales

We obtain a sharp characterization of the Euclidean ball among all convex bodies K whose boundary has a pointwise k-th mean curvature not smaller than a geometric constant at almost all normal points. This geometric constant depends only on…

Differential Geometry · Mathematics 2020-10-30 Mario Santilli

The isodiametric inequality is derived from the isoperimetric inequality trough a variational principle, establishing that balls maximize the perimeter among convex sets with fixed diameter. This principle brings also quantitative…

Metric Geometry · Mathematics 2015-03-19 Francesco Maggi , Marcello Ponsiglione , Aldo Pratelli

We show that the Euclidean ball has the smallest volume among sublevel sets of nonnegative forms of bounded Bombieri norm as well as among sublevel sets of sum of squares forms whose Gram matrix has bounded Frobenius or nuclear (or, more…

Optimization and Control · Mathematics 2020-07-28 Khazhgali Kozhasov , Jean-Bernard Lasserre

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