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Existence of nicely bounded sections of two symmetric convex bodies K and L implies that the intersection of random rotations of K and L is nicely bounded. For L = subspace, this main result immediately yields the unexpected phenomenon: "If…

Functional Analysis · Mathematics 2016-12-23 Roman Vershynin

Is it true that a convex body $K$ being complete and reduced with respect to some gauge body $C$ is necessarily of constant width, that is, satisfies $K-K=\rho(C-C)$ for some $\rho>0$? We prove this implication for several cases including…

Metric Geometry · Mathematics 2016-02-26 René Brandenberg , Bernardo González Merino , Thomas Jahn , Horst Martini

We prove that for every convex body $K$ with the center of mass at the origin and every $\varepsilon\in \left(0,\frac{1}{2}\right)$, there exists a convex polytope $P$ with at most $e^{O(d)}\varepsilon^{-\frac{d-1}{2}}$ vertices such that…

Classical Analysis and ODEs · Mathematics 2017-05-05 Márton Naszódi , Fedor Nazarov , Dmitry Ryabogin

Let $\Omega$ be an open convex domain of the complex plane. We study constants K such that $\Omega$ is K-spectral or complete K-spectral for each continuous linear Hilbert space operator with numerical range included in $\Omega$. Several…

Functional Analysis · Mathematics 2018-06-05 Catalin Badea , Michel Crouzeix , Bernard Delyon

Motivated by the relative differential geometry, where the Euclidean normal vector of hypersurfaces is generalized by a relative normalization, we introduce anisotropic area measures of convex bodies, constructed with respect to a gauge…

Metric Geometry · Mathematics 2025-06-17 Rolf Schneider

We study geometric properties of coordinate projections. Among other results, we show that if a body K in R^n has an "almost extremal" volume ratio, then it has a projection of proportional dimension which is close to the cube. We compare…

Functional Analysis · Mathematics 2016-12-23 S. Mendelson , R. Vershynin

Every convex body K in R^n has a coordinate projection PK that contains at least vol(0.1 K) cells of the integer lattice PZ^n, provided this volume is at least one. Our proof of this counterpart of Minkowski's theorem is based on an…

Functional Analysis · Mathematics 2016-12-23 Roman Vershynin

The purpose of this paper is to introduce the new concept of weighted floating functions associated with log concave or $s$-concave functions. This leads to new notions of weighted functional affine surface areas. Their relation to more…

Metric Geometry · Mathematics 2024-03-06 Carsten Schütt , Christoph Thaele , Nicola Turchi , Elisabeth M. Werner

We introduce floating bodies for convex, not necessarily bounded subsets of $\mathbb{R}^n$. This allows us to define floating functions for convex and log concave functions and log concave measures. We establish the asymptotic behavior of…

Functional Analysis · Mathematics 2018-08-07 Ben Li , Carsten Schuett , Elisabeth M. Werner

We define a new structure on a space endowed with convexities, and call it a fractoconvex structure (or, a space with fractoconvexity). We introduce two operations on a set of fractoconvexities and in a special case we show that they…

General Mathematics · Mathematics 2024-08-20 Aidar Dulliev

In this paper we prove different functional inequalities extending the classical Rogers-Shephard inequalities for convex bodies. The original inequalities provide an optimal relation between the volume of a convex body and the volume of…

Functional Analysis · Mathematics 2016-09-14 David Alonso-Gutiérrez , Bernardo González Merino , C. Hugo Jiménez , Rafael Villa

The $K$-hull of a compact set $A\subset\mathbb{R}^d$, where $K\subset \mathbb{R}^d$ is a fixed compact convex body, is the intersection of all translates of $K$ that contain $A$. A set is called $K$-strongly convex if it coincides with its…

Metric Geometry · Mathematics 2021-10-06 Alexander Marynych , Ilya Molchanov

We describe all metric spaces that have sufficently many affine functions. As an application we obtain a metric characterization of linear-convex subsets of Banach spaces.

Metric Geometry · Mathematics 2013-04-25 Petra Schwer , Alexander Lytchak

The (delta-) normal cone to an arbitrary intersection of sublevel sets of proper, lower semicontinuous, and convex functions is characterized, using either epsilon-subdifferentials at the nominal point or exact subdifferentials at nearby…

Optimization and Control · Mathematics 2017-10-30 Abderrahim Hantoute , Anton Svensson

Let $K$ be a convex body in $\mathbb{R} ^d$, with $d = 2,3$. We determine sharp sufficient conditions for a set $E$ composed of $1$, $2$, or $3$ points of ${\rm bd}K$, to contain at least one endpoint of a diameter of $K$ (for $d=2,3$). We…

Metric Geometry · Mathematics 2019-10-28 Jin-ichi Itoh , Costin Vîlcu , Liping Yuan , Tudor Zamfirescu

Let $1\leq i \leq k < n$ be integers. We prove the following exact inequalities for any convex body $K\subset\mathbb{R}^n$ with centroid at the origin, and any $k$-dimensional subspace $E\subset \mathbb{R}^n$: \begin{align*} &V_i \big(…

Metric Geometry · Mathematics 2018-09-18 Matthew Stephen , Vladyslav Yaskin

The minimizers of the anisotropic fractional isoperimetric inequality with respect to the convex body $K$ in $\mathbb{R}^n$ are shown to be equivalent to star bodies whenever $K$ is strictly convex and unconditional. From this a…

Functional Analysis · Mathematics 2020-05-01 Andreas Kreuml

In this paper, we establish a general inequality for locally strongly convex centroaffine hypersurfaces in $\mathbb{R}^{n+1}$ involving the norm of the covariant derivatives of both the difference tensor $K$ and the Tchebychev vector field…

Differential Geometry · Mathematics 2018-01-16 Xiuxiu Cheng , Zejun Hu

In geometry, there are several challenging problems studying numbers associated to convex bodies. For example, the packing density problem, the kissing number problem, the covering density problem, the packing-covering constant problem,…

Metric Geometry · Mathematics 2014-02-18 Chuanming Zong

We present several analogies between convex geometry and the theory of holomorphic line bundles on smooth projective varieties or K\"ahler manifolds. We study the relation between positive products and mixed volumes. We define and study a…

Algebraic Geometry · Mathematics 2023-06-22 Brian Lehmann , Jian Xiao