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Exploring the Numerical Range of Block Toeplitz Operators

Abstract

dc:description.abstract

<p>We will explore the numerical range of the block Toeplitz operator with symbol function \phi(z)=A0+zA1, where A0, A1 \in M2(\mathbb{C}). A full characterization of the numerical range of this operator proves to be quite difficult and so we will focus on characterizing the boundary of the related set, \{W(A0+zA1) : z \in \partial \mathbb{D}\}, in a specific case. We will use the theory of envelopes to explore what the boundary looks like and we will use geometric arguments to explore the number of flat portions on the boundary. We will then make a conjecture as to the number of flat portions on the boundary of the numerical range for any \(2 \times 2\) matrices A0 and A1. We finish by providing examples of flat portions on the boundary of the numerical range when A0, A1 \in Mn(\mathbb{C}), for \(3 \leq n \leq 5\).</p>

Degree

thesis:*
Name thesis:degree_name
MS in Mathematics
Discipline thesis:degree_discipline
Mathematics
Year dc:date.available
2022

Author and committee

dc:creator, dc:contributor.*
Author dc:creator
  • Randell, Brooke
Contributors dc:contributor
  • Linda Patton
  • Mathematics
  • College of Science and Mathematics

Subjects

dc:subject × 2

Identifiers

dc:identifier.*
OAI identifier oai:identifier
oai:digitalcommons.calpoly.edu:theses-4042

Chain of custody

source
Harvested from
Cal Poly
Base URL
digitalcommons.calpoly.edu/do/oai/
Last updated
2026-07-24
Source record
OAI-PMH GetRecord
citation

Randell, Brooke. Exploring the Numerical Range of Block Toeplitz Operators. 2022. https://digitalcommons.calpoly.edu/theses/2467