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Given a convex set and an interior point close to the boundary, we prove the existence of a supporting hyperplane whose distance to the point is controlled, in a dimensionally quantified way, by the thickness of the convex set in the…

Analysis of PDEs · Mathematics 2011-07-07 Alessio Figalli , Young-Heon Kim , Robert J. McCann

P\'al's classical isominwidth inequality states that the regular triangle has minimal area among plane convex bodies of minimal width $w$. A similar result is the Blaschke--Lebesgue inequality that states that Reuleaux triangles minimize…

Metric Geometry · Mathematics 2026-02-24 Ferenc Fodor , Nathan Robock , Ádám Sagmeister

The oloid is the convex hull of two circles with equal radius in perpendicular planes so that the center of each circle lies on the other circle. We calculate the mean width of the oloid in two ways, first via the integral of mean…

Metric Geometry · Mathematics 2019-03-22 Uwe Bäsel

In this note we link symplectic and convex geometry by relating two seemingly different open conjectures: a symplectic isoperimetric-type inequality for convex domains, and Mahler's conjecture on the volume product of centrally symmetric…

Metric Geometry · Mathematics 2015-01-14 Shiri Artstein-Avidan , Roman Karasev , Yaron Ostrover

In his paper "On the Schlafli differential equality", J. Milnor conjectured that the volume of n-dimensional hyperbolic and spherical simplices, as a function of the dihedral angles, extends continuously to the closure of the space of…

Geometric Topology · Mathematics 2007-05-23 Igor Rivin

A variant of the flatness problem from integer programming is studied, in which one considers convex bodies in $\mathbb{R}^d$ with at most $k$ interior lattice points. The maximum lattice width of such a body is denoted by Flt(d,k) and it…

Metric Geometry · Mathematics 2026-05-01 Gennadiy Averkov , Giulia Codenotti , Ansgar Freyer , Kyle Huang

For a convex body $K\subset\mathbb{R}^d$ the mean distance $\Delta(K)=\mathbb{E}|X_1-X_2|$ is the expected Euclidean distance of two independent and uniformly distributed random points $X_1,X_2\in K$. Optimal lower and upper bounds for…

Metric Geometry · Mathematics 2021-06-22 Gilles Bonnet , Anna Gusakova , Christoph Thäle , Dmitry Zaporozhets

For any origin-symmetric convex body $K$ in $\mathbb{R}^n$ in isotropic position, we obtain the bound: \[ M^*(K) \leq C \sqrt{n} \log(n)^2 L_K ~, \] where $M^*(K)$ denotes (half) the mean-width of $K$, $L_K$ is the isotropic constant of…

Functional Analysis · Mathematics 2014-05-09 Emanuel Milman

This thesis consists of five papers about reduced spherical convex bodies and in particular spherical bodies of constant width on the $d$-dimensional sphere $S^d$. In paper I we present some facts describing the shape of reduced bodies of…

Metric Geometry · Mathematics 2024-09-12 Michał Musielak

We consider a generalization of the hyperplane problem to arbitrary measures in place of volume and to sections of lower dimensions. We prove this generalization for unconditional convex bodies and for duals of bodies with bounded volume…

Metric Geometry · Mathematics 2015-03-24 Alexander Koldobsky

The width of a convex curve in the plane is the minimal distance between a pair of parallel supporting lines of the curve. In this paper we study the width of nodal lines of eigenfunctions of the Laplacian on the standard flat torus. We…

Analysis of PDEs · Mathematics 2015-05-20 Jean Bourgain , Zeev Rudnick

A centrally symmetric convex body is a convex compact set with non-empty interior that is symmetric about the origin. Of particular interest are those that are both smooth and strictly convex -- known here as regular symmetric bodies --…

Metric Geometry · Mathematics 2024-01-18 Sean Dewar

Similarly to the classic notion in $E^d$, a subset of a positive diameter below $\frac{\pi}{2}$ of a hemisphere of the sphere $S^d$ is called complete, provided adding any extra point increases its diameter. Complete sets are convex bodies…

Metric Geometry · Mathematics 2020-10-08 Marek Lassak

The variance conjecture in Asymptotic Convex Geometry stipulates that the Euclidean norm of a random vector uniformly distributed in a (properly normalised) high-dimensional convex body $K\subset {\mathbb R}^n$ satisfies a Poincar\'e-type…

Functional Analysis · Mathematics 2018-05-09 Beatrice-Helen Vritsiou

We show that the number of lattice directions in which a d-dimensional convex body in R^d has minimum width is at most 3^d-1, with equality only for the regular cross-polytope. This is deduced from a sharpened version of the 3^d-theorem due…

Combinatorics · Mathematics 2017-10-10 Jan Draisma , Tyrrell B. McAllister , Benjamin Nill

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

High proved the following theorem. If the intersections of any two congruent copies of a plane convex body are centrally symmetric, then this body is a circle. In our paper we extend the theorem of High to spherical, Euclidean and…

Metric Geometry · Mathematics 2018-07-05 J. Jerónimo-Castro , E. Makai,

We study the regularity of solutions to an optimal transportation problem where the dimension of the source is larger than that of the target. We demonstrate that if the target is $c$-convex, then the source has a canonical foliation whose…

Analysis of PDEs · Mathematics 2010-08-27 Brendan Pass

In this work we discuss a conjecture of Viterbo relating the symplectic capacity of a convex body and its volume. The conjecture states that among all 2n-dimensional convex bodies with a given volume the euclidean ball has maximal…

Symplectic Geometry · Mathematics 2007-05-23 Shiri Artstein-Avidan , Yaron Ostrover

Let $M$ be a compact $n$-dimensional Riemannian manifold with nonnegative Ricci curvature and mean convex boundary $\partial M$. Assume that the mean curvature $H$ of the boundary $\partial M$ satisfies $H \geq (n-1) k >0$ for some positive…

Differential Geometry · Mathematics 2020-01-06 Martin Li