A reverse isoperimetric inequality in three-dimensional space forms

Fuente: arXiv
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Main Authors: Drach, Kostiantyn, Solanes, Gil, Tatarko, Kateryna
Format: Preprint
Published: 2026
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author Drach, Kostiantyn
Solanes, Gil
Tatarko, Kateryna
author_facet Drach, Kostiantyn
Solanes, Gil
Tatarko, Kateryna
contents A $λ$-convex body in a three-dimensional space form $M^3(c)$ of constant curvature $c$ is a compact convex set $K$ whose boundary $\partial K$ has normal curvatures bounded below by a constant $λ>0$ (in a weak sense). Within this class, we prove a sharp reverse isoperimetric inequality: among all $λ$-convex bodies in $M^3(c)$, with a fixed surface area, the body of minimal volume is the $λ$-convex lens, i.e., the domain bounded by two totally umbilical caps of curvature $λ$. Moreover, this minimizer is unique. This result confirms Borisenko's Conjecture in the three-dimensional model spaces of constant curvature for $c\neq 0$, and complements recent progress on the conjecture in the Euclidean case $c=0$. As a by-product, our method also yields an alternative proof of the corresponding reverse isoperimetric inequality in two-dimensional hyperbolic space.
format Preprint
id arxiv_https___arxiv_org_abs_2603_08132
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A reverse isoperimetric inequality in three-dimensional space forms
Drach, Kostiantyn
Solanes, Gil
Tatarko, Kateryna
Differential Geometry
Metric Geometry
A $λ$-convex body in a three-dimensional space form $M^3(c)$ of constant curvature $c$ is a compact convex set $K$ whose boundary $\partial K$ has normal curvatures bounded below by a constant $λ>0$ (in a weak sense). Within this class, we prove a sharp reverse isoperimetric inequality: among all $λ$-convex bodies in $M^3(c)$, with a fixed surface area, the body of minimal volume is the $λ$-convex lens, i.e., the domain bounded by two totally umbilical caps of curvature $λ$. Moreover, this minimizer is unique. This result confirms Borisenko's Conjecture in the three-dimensional model spaces of constant curvature for $c\neq 0$, and complements recent progress on the conjecture in the Euclidean case $c=0$. As a by-product, our method also yields an alternative proof of the corresponding reverse isoperimetric inequality in two-dimensional hyperbolic space.
title A reverse isoperimetric inequality in three-dimensional space forms
topic Differential Geometry
Metric Geometry
url https://arxiv.org/abs/2603.08132