Blaschke products, level sets, and Crouzeix's conjecture

Publication Date

2024

Description

We study several problems motivated by Crouzeix's conjecture, which we consider in the special setting of model spaces and compressions of the shift with finite Blaschke products as symbols. We pose a version of the conjecture in this setting, called the level set Crouzeix (LSC) conjecture, and establish structural and uniqueness properties for (open) level sets of finite Blaschke products that allow us to prove the LSC conjecture in several cases. In particular, we use the geometry of the numerical range to prove the LSC conjecture for compressions of the shift corresponding to unicritical Blaschke products of degree 4.

Journal

Journal d'Analyse Mathématique

Volume

152

Issue

1

First Page

217

Last Page

254

Department

Mathematics

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