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Let $E$ be a real vector space with dual space $E^*$ and let $C\subset E$ be a convex subset with more than one point. Let $f : C\to\mathbb{R}$ be a function satisfying a mild stability property at 'flat' points of the (relative) boundary…

Optimization and Control · Mathematics 2015-04-21 Khanh Pham Duy , Marc Lassonde

The distance between convex bodies \(K, L \subseteq \R^n\) is defined as \[ d(K,L)= \inf \left\{ \lambda \ge 1: \ L-x \subseteq T (K-y) \subseteq \lambda (L-x) \right\}, \] where the infimum is taken over all \(x,y \in \R^n\) and all…

Functional Analysis · Mathematics 2026-02-27 Han Huang , Mark Rudelson

We study the lower bound for Koldobsky's slicing inequality. We show that there exists a measure $\mu$ and a symmetric convex body $K \subseteq \mathbb{R}^n$, such that for all $\xi\in S^{n-1}$ and all $t\in \mathbb{R},$…

Metric Geometry · Mathematics 2023-07-19 Bo'az Klartag , Galyna V. Livshyts

We study operator log-convex functions on $(0,\infty)$, and prove that a continuous nonnegative function on $(0,\infty)$ is operator log-convex if and only if it is operator monotone decreasing. Several equivalent conditions related to…

Functional Analysis · Mathematics 2014-12-23 Tsuyoshi Ando , Fumio Hiai

Let $K \subset {\mathbb R}^2$ be an $o$-symmetric convex body, and $K^*$ its polar body. Then we have $|K|\cdot |K^*| \ge 8$, with equality if and only if $K$ is a parallelogram. ($| \cdot |$ denotes volume). If $K \subset {\mathbb R}^2$ is…

Metric Geometry · Mathematics 2015-07-07 K. J. Böröczky , E. Makai , M. Meyer , S. Reisner

We prove that if $f:(a,b)\to\mathbb{R}$ is convex, then for any $\varepsilon>0$ there is a convex function $g\in C^2(a,b)$ such that $|\{f\neq g\}|<\varepsilon$ and $\Vert f-g\Vert_\infty<\varepsilon$.

Classical Analysis and ODEs · Mathematics 2025-11-11 Paweł Goldstein , Piotr Hajłasz

The Wills functional $\mathcal{W}(K)$ of a convex body $K$, defined as the sum of its intrinsic volumes $\mathrm{V}_i(K)$, turns out to have many interesting applications and properties. In this paper we make profit of the fact that it can…

Metric Geometry · Mathematics 2020-02-17 David Alonso-Gutiérrez , María A. Hernández Cifre , Jesús Yepes Nicolás

We establish new geometric inequalities comparing the volumes of sections and projections of a convex body, whose barycenter or Santal\'o point is at the origin, with those of its inner and outer regularizations. We also provide functional…

Metric Geometry · Mathematics 2025-11-06 Natalia Tziotziou

In this paper, we provide a rigorous computer-assisted proof (CAP) of the conjecture that there exists a unique convex central configuration for any four fixed positive masses in a given order belonging to a closed domain in the mass space.…

Dynamical Systems · Mathematics 2023-08-01 Shanzhong Sun , Zhifu Xie , Peng You

We consider a new subclass $\widetilde{\mathcal{K}}_u$ of close-to-convex functions in the unit disk $\mathbb{D}:=\{z\in\mathbb{C}:|z|<1\}$. For this class, we obtain sharp estimates of the Fekete-Szeg\"{o} problem, growth and distortion…

Complex Variables · Mathematics 2025-05-20 Md Nurezzaman

In this article we show the following result: if $C$ is an $n$-dimensional convex and compact subset, $f:C\rightarrow[0,\infty)$ is concave, and $\phi:[0,\infty)\rightarrow[0,\infty)$ is a convex function with $\phi(0)=0$, we then…

Functional Analysis · Mathematics 2021-01-29 Bernardo González Merino

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

It is proved that the simplex is a strict local minimum for the volume product, P(K)=min(vol(K) vol(K^z)), K^z is the polar body of K with respect to z, the minimum is taken over z in the interior of K, in the Banach-Mazur space of…

Metric Geometry · Mathematics 2014-01-14 Jaegil Kim , Shlomo Reisner

We construct a differentiable locally Lipschitz function $f$ in $\mathbb{R}^{N}$ with the property that for every convex body $K\subset \mathbb{R}^N$ there exists $\bar x \in \mathbb{R}^N$ such that $K$ coincides with the set $\partial_L…

Classical Analysis and ODEs · Mathematics 2024-09-13 Aris Daniilidis , Robert Deville , Sebastian Tapia-Garcia

We give a systematic and thorough study of geometric notions and results connected to Minkowski's measure of symmetry and the extension of the well-known Minkowski functional to arbitrary, not necessarily symmetric convex bodies K on any…

Classical Analysis and ODEs · Mathematics 2007-05-23 Szilard Gy. Revesz

For a permutationally invariant unconditional convex body K in R^n we define a finite sequence (K_j), j = 1, ..., n of projections of the body K to the space spanned by first j vectors of the standard basis of R^n. We prove that the…

Functional Analysis · Mathematics 2013-03-04 Piotr Nayar , Tomasz Tkocz

We prove that, if $W \subset \mathbb{R}^n$ is a locally strongly convex body (not necessarily compact), then for any open set $V \supset \partial W$ and $\varepsilon>0$, and $V \supset \partial W$ is open, then there exists a $C^2$ locally…

Classical Analysis and ODEs · Mathematics 2024-10-11 Daniel Azagra , Marjorie Drake , Piotr Hajłasz

We show that if $X$ is a Banach space whose dual $X^{*}$ has an equivalent locally uniformly rotund (LUR) norm, then for every open convex $U\subseteq X$, for every $\varepsilon >0$, and for every continuous and convex function $f:U…

Functional Analysis · Mathematics 2014-11-04 Daniel Azagra , Carlos Mudarra

The section volume function $A_K(\xi,t), \ \xi \in \mathbb R^n, \ t \in \mathbb R,$ of a body $K \subset \mathbb R^n$ evaluates the $(n-1)$-dimensional volume of the cross-section $K$ by the hyperplane $\{ x \cdot \xi=t \}.$ We are…

Metric Geometry · Mathematics 2024-10-01 Mark Agranovsky

We prove that the reciprocal of the volume of the polar bodies, about the Santal\'o point, of a {\em shadow system} of convex bodies $K_t$, is a convex function of $t$. Thus extending to the non-symmetric case a result of Campi and Gronchi.…

Metric Geometry · Mathematics 2008-07-14 Mathieu Meyer , Shlomo Reisner