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We show that in Euclidean 3-space any closed curve which lies outside the unit sphere and contains the sphere within its convex hull has length at least $4\pi$. Equality holds only when the curve is composed of $4$ semicircles of length…

Differential Geometry · Mathematics 2021-07-23 Mohammad Ghomi , James Wenk

It has recently been established byWang and Xia [WX] that local minimizers of perimeter within a ball subject to a volume constraint must be spherical caps or planes through the origin. This verifies a conjecture of the authors and is in…

Analysis of PDEs · Mathematics 2017-11-02 Peter Sternberg , Kevin Zumbrun

We consider a smooth Euclidean solid cone endowed with a smooth homogeneous density function used to weight Euclidean volume and hypersurface area. By assuming convexity of the cone and a curvature-dimension condition we prove that the…

Differential Geometry · Mathematics 2013-04-17 Antonio Cañete , César Rosales

We prove two weighted geometric inequalities that hold for strictly mean convex and star-shaped hypersurfaces in Euclidean space. The first one involves the weighted area and the area of the hypersurface and also the volume of the region…

Differential Geometry · Mathematics 2020-01-08 Frederico Girão , Diego Rodrigues

The classic double bubble theorem says that the least-perimeter way to enclose and separate two prescribed volumes in $\mathbb{R}^N$ is the standard double bubble. We seek the optimal double bubble in $\mathbb{R}^N$ with density, which we…

Semiconvection occurs in regions of stars and planets that are unstable to overturning convection according to the Schwarzschild criterion, yet stable according to the Ledoux criterion. Previous simulations in Cartesian boxes have advanced…

Solar and Stellar Astrophysics · Physics 2025-03-19 J. R. Fuentes

In this paper we consider the problem of minimizing the relative perimeter under a volume constraint in the interior of a conically bounded convex set, i.e., an unbounded convex body admitting an \emph{exterior} asymptotic cone. Results…

Differential Geometry · Mathematics 2014-10-15 Manuel Ritoré , Efstratios Vernadakis

We consider a spherical thick shell immersed in two different spherically symmetric space-times. Using the fact that the boundaries of the thick shell with two embedding space-times must be nonsingular hypersurfaces, we develop a scheme to…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Samad Khakshournia , Reza Mansouri

We show that in all dimensions d>2, there exists an asymmetric convex body of revolution all of whose maximal hyperplane sections have the same volume. This gives the negative answer to the question posed by V. Klee in 1969.

Metric Geometry · Mathematics 2012-01-04 Fedor Nazarov , Dmitry Ryabogin , Artem Zvavitch

Newton's problem of the body of minimal aerodynamic resistance is traditionally stated in the class of {\it convex} axially symmetric bodies with fixed length and width. We state and solve the minimal resistance problem in the wider class…

Optimization and Control · Mathematics 2008-04-28 Alexander Plakhov , Alena Aleksenko

Let $K\subseteq{\mathbb R}^n$ be a convex semialgebraic set. The semidefinite extension degree ${\mathrm{sxdeg}}(K)$ of $K$ is the smallest number $d$ such that $K$ is a linear image of an intersection of finitely many spectrahedra, each of…

Algebraic Geometry · Mathematics 2024-10-15 Claus Scheiderer

In light of the log-Brunn-Minkowski conjecture, various attempts have been made to define the geometric mean of convex bodies. Many of these constructions are fairly complex and/or fail to satisfy some natural properties one would expect of…

Metric Geometry · Mathematics 2024-05-02 René Brandenberg , Florian Grundbacher

A subset of the sphere is said short if it is contained in an open hemisphere. A short closed set which is geodesically convex is called a cap. The following theorem holds: 1. The minimal number of short closed sets covering the $n$-sphere…

Geometric Topology · Mathematics 2015-12-22 A. B. Németh

We show that the shortest closed geodesic on a 2-sphere with non-negative curvature has length bounded above by three times the diameter. We prove a new isoperimetric inequality for 2-spheres with pinched curvature; this allows us to…

Differential Geometry · Mathematics 2021-09-08 Ian Adelstein , Franco Vargas Pallete

Smooth axially symmetric Helfrich topological spheres are either round or else they must satisfy a second order equation known as the reduced membrane equation [17]. In this paper, we show that, conversely, axially symmetric closed genus…

Differential Geometry · Mathematics 2026-02-06 Rafael López , Bennett Palmer , Álvaro Pámpano

The approximability of a convex body is a number which measures the difficulty to approximate that body by polytopes. We prove that twice the approximability is equal to the volume entropy for a Hilbert geometry in dimension two end three…

Metric Geometry · Mathematics 2017-03-01 Constantin Vernicos

We establish a lower bound for the surface area of a closed, convex hypersurface in Euclidean space in terms of its displacement under continuous maps. As a result, a hypothesized lower bound for the volume of a Riemannian $n$-sphere,…

Differential Geometry · Mathematics 2026-04-23 James Dibble , Joseph Hoisington

We investigate how thin structures change their shape in response to non-mechanical stimuli that can be interpreted as variations in the structure's natural curvature. Starting from the theory of non-Euclidean plates and shells, we derive…

Soft Condensed Matter · Physics 2017-06-08 Matteo Pezzulla , Norbert Stoop , Xin Jiang , Douglas P. Holmes

The lower dimensional Busemann-Petty problem asks, whether n-dimensional centrally symmetric convex bodies with smaller i-dimensional central sections necessarily have smaller volumes. The paper contains a complete solution to the problem…

Functional Analysis · Mathematics 2007-05-23 Boris Rubin

In an Euclidean $d$-space, the container problem asks to pack $n$ equally sized spheres into a minimal dilate of a fixed container. If the container is a smooth convex body and $d\geq 2$ we show that solutions to the container problem can…

Metric Geometry · Mathematics 2011-10-20 Achill Schuermann