On unbalanced difference bodies and Godbersen's conjecture

Fuente: arXiv
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Auteurs principaux: Artstein-Avidan, Shiri, Putterman, Eli
Format: Preprint
Publié: 2024
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author Artstein-Avidan, Shiri
Putterman, Eli
author_facet Artstein-Avidan, Shiri
Putterman, Eli
contents The longstanding Godbersen's conjecture states that for any convex body $K \subset \mathbb R^n$ of volume $1$ and any $j \in \{0, \ldots, n\}$, the mixed volume $V_j = V(K[j], -K[n - j])$ is bounded by $\binom{n}{j}$, with equality if and only if $K$ is a simplex. We demonstrate that several consequences of this conjecture are true: certain families of linear combinations of the $V_j$, arising from different geometric constructions, are bounded above by their values when one substitutes $\binom{n}{j}$ for $V_j$, with equality if and only if $K$ is a simplex. One of our results implies that for any $K$ of volume $1$ we have $\frac{1}{n + 1} \sum_{j = 0}^n \binom{n}{j}^{-1} V_j \le 1$, showing that Godbersen's conjecture holds ``on average'' for any body. Another result generalizes the well-known Rogers-Shephard inequality for the difference body.
format Preprint
id arxiv_https___arxiv_org_abs_2412_05308
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On unbalanced difference bodies and Godbersen's conjecture
Artstein-Avidan, Shiri
Putterman, Eli
Metric Geometry
52A39
The longstanding Godbersen's conjecture states that for any convex body $K \subset \mathbb R^n$ of volume $1$ and any $j \in \{0, \ldots, n\}$, the mixed volume $V_j = V(K[j], -K[n - j])$ is bounded by $\binom{n}{j}$, with equality if and only if $K$ is a simplex. We demonstrate that several consequences of this conjecture are true: certain families of linear combinations of the $V_j$, arising from different geometric constructions, are bounded above by their values when one substitutes $\binom{n}{j}$ for $V_j$, with equality if and only if $K$ is a simplex. One of our results implies that for any $K$ of volume $1$ we have $\frac{1}{n + 1} \sum_{j = 0}^n \binom{n}{j}^{-1} V_j \le 1$, showing that Godbersen's conjecture holds ``on average'' for any body. Another result generalizes the well-known Rogers-Shephard inequality for the difference body.
title On unbalanced difference bodies and Godbersen's conjecture
topic Metric Geometry
52A39
url https://arxiv.org/abs/2412.05308