$L^p$-polarity, Mahler volumes, and the isotropic constant

Fuente: arXiv
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Autores principales: Berndtsson, Bo, Mastrantonis, Vlassis, Rubinstein, Yanir A.
Formato: Preprint
Publicado: 2023
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author Berndtsson, Bo
Mastrantonis, Vlassis
Rubinstein, Yanir A.
author_facet Berndtsson, Bo
Mastrantonis, Vlassis
Rubinstein, Yanir A.
contents This article introduces $L^p$ versions of the support function of a convex body $K$ and associates to these canonical $L^p$-polar bodies $K^{\circ, p}$ and Mahler volumes $\mathcal{M}_p(K)$. Classical polarity is then seen as $L^\infty$-polarity. This one-parameter generalization of polarity leads to a generalization of the Mahler conjectures, with a subtle advantage over the original conjecture: conjectural uniqueness of extremizers for each $p\in(0,\infty)$. We settle the upper bound by demonstrating the existence and uniqueness of an $L^p$-Santaló point and an $L^p$-Santaló inequality for symmetric convex bodies. The proof uses Ball's Brunn--Minkowski inequality for harmonic means, the classical Brunn--Minkowski inequality, symmetrization, and a systematic study of the $\mathcal{M}_p$ functionals. Using our results on the $L^p$-Santaló point and a new observation motivated by complex geometry, we show how Bourgain's slicing conjecture can be reduced to lower bounds on the $L^p$-Mahler volume coupled with a certain conjectural convexity property of the logarithm of the Monge--Ampère measure of the $L^p$-support function. We derive a suboptimal version of this convexity using Kobayashi's theorem on the Ricci curvature of Bergman metrics to illustrate this approach to slicing. Finally, we explain how Nazarov's complex analytic approach to the classical Mahler conjecture is instead precisely an approach to the $L^1$-Mahler conjecture.
format Preprint
id arxiv_https___arxiv_org_abs_2304_14363
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle $L^p$-polarity, Mahler volumes, and the isotropic constant
Berndtsson, Bo
Mastrantonis, Vlassis
Rubinstein, Yanir A.
Functional Analysis
Complex Variables
This article introduces $L^p$ versions of the support function of a convex body $K$ and associates to these canonical $L^p$-polar bodies $K^{\circ, p}$ and Mahler volumes $\mathcal{M}_p(K)$. Classical polarity is then seen as $L^\infty$-polarity. This one-parameter generalization of polarity leads to a generalization of the Mahler conjectures, with a subtle advantage over the original conjecture: conjectural uniqueness of extremizers for each $p\in(0,\infty)$. We settle the upper bound by demonstrating the existence and uniqueness of an $L^p$-Santaló point and an $L^p$-Santaló inequality for symmetric convex bodies. The proof uses Ball's Brunn--Minkowski inequality for harmonic means, the classical Brunn--Minkowski inequality, symmetrization, and a systematic study of the $\mathcal{M}_p$ functionals. Using our results on the $L^p$-Santaló point and a new observation motivated by complex geometry, we show how Bourgain's slicing conjecture can be reduced to lower bounds on the $L^p$-Mahler volume coupled with a certain conjectural convexity property of the logarithm of the Monge--Ampère measure of the $L^p$-support function. We derive a suboptimal version of this convexity using Kobayashi's theorem on the Ricci curvature of Bergman metrics to illustrate this approach to slicing. Finally, we explain how Nazarov's complex analytic approach to the classical Mahler conjecture is instead precisely an approach to the $L^1$-Mahler conjecture.
title $L^p$-polarity, Mahler volumes, and the isotropic constant
topic Functional Analysis
Complex Variables
url https://arxiv.org/abs/2304.14363