Date of Award
Spring 5-15-2016
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
This thesis concerns three distinct problems in operator theory and complex analysis. In Chapter 2, we study the following problem: On the Hardy space H^2, when is the product of a Hankel operator and a Toeplitz operator compact? We give necessary and sucient conditions for when such a product H_fT_g is compact. In Chapter 3, we discuss hyponormal Toeplitz operators. We show that for those operators, there exists a lower bound for the area of the spectrum. This extends the known estimate for the spectral area of Toeplitz operators with an analytic symbol. This part is joint work with Dmitry Khavinson. In Chapter 4, we study the Bohr radius R_n for the class of complex polynomials of degree at most n. Bohr's theorem showed that R_n goes to 1/3 as n tends to infinity. We are interested in the rate of convergence and proved an asymptotic formula that was conjectured by R. Fournier in 2008.
Language
English (en)
Chair and Committee
John McCarthy
Committee Members
James Gill, Gregory Knese, Richard Rochberg, Xiang Tang,
Recommended Citation
Chu, Cheng, "Three Problems in Operator Theory and Complex Analysis" (2016). Arts & Sciences Electronic Theses and Dissertations. 773.
https://openscholarship.wustl.edu/art_sci_etds/773
Comments
Permanent URL: https://doi.org/10.7936/K7HH6HCG