Three radii associated to Schur functions on the polydisk

Fuente: arXiv
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1. Verfasser: Knese, Greg
Format: Preprint
Veröffentlicht: 2024
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author Knese, Greg
author_facet Knese, Greg
contents This article examines three radii associated to bounded analytic functions on the polydisk: the well-known Bohr radius, the Bohr-Agler radius, and the Schur-Agler radius. We prove explicit upper and lower bounds for the Bohr-Agler radius, an explicit lower bound for the Schur-Agler radius, and an asymptotic upper bound for the Schur-Agler radius. The Bohr-Agler radius obeys the same (known) asymptotic as the Bohr radius while we show the Schur-Agler radius is roughly of the same growth as the Bohr radius. As a corollary, we bound the Bohr radius on the bidisk below by 0.3006. Finally, we improve some estimates of P.G. Dixon on Agler norms of homogeneous polynomials using some modern inequalities.
format Preprint
id arxiv_https___arxiv_org_abs_2410_21693
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Three radii associated to Schur functions on the polydisk
Knese, Greg
Complex Variables
Functional Analysis
47A48, 47A13, 32A35, 32A38
This article examines three radii associated to bounded analytic functions on the polydisk: the well-known Bohr radius, the Bohr-Agler radius, and the Schur-Agler radius. We prove explicit upper and lower bounds for the Bohr-Agler radius, an explicit lower bound for the Schur-Agler radius, and an asymptotic upper bound for the Schur-Agler radius. The Bohr-Agler radius obeys the same (known) asymptotic as the Bohr radius while we show the Schur-Agler radius is roughly of the same growth as the Bohr radius. As a corollary, we bound the Bohr radius on the bidisk below by 0.3006. Finally, we improve some estimates of P.G. Dixon on Agler norms of homogeneous polynomials using some modern inequalities.
title Three radii associated to Schur functions on the polydisk
topic Complex Variables
Functional Analysis
47A48, 47A13, 32A35, 32A38
url https://arxiv.org/abs/2410.21693