Zobrazeno 1 - 10
of 88
pro vyhledávání: '"Kelly Bickel"'
Publikováno v:
ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE. :449-494
We analyze the behavior of rational inner functions on the unit bidisk near singularities on the distinguished boundary $\mathbb{T}^2$ using level sets. We show that the unimodular level sets of a rational inner function $\phi$ can be parametrized wi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::cbdebf429eda81a8c49be16cd09d1b47
https://doi.org/10.2422/2036-2145.201804_025
https://doi.org/10.2422/2036-2145.201804_025
Autor:
Kelly Bickel, Elias Wegert, Felix L. Schwenninger, Thomas Ransford, Pamela Gorkin, Anne Greenbaum
Publikováno v:
Computational Methods and Function Theory, 20(3-4), 701-728. Springer
In this paper, we establish several results related to Crouzeix's conjecture. We show that the conjecture holds for contractions with eigenvalues that are sufficiently well-separated. This separation is measured by the so-called separation constant,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::76bf230ad9334407850d1a0c3666bc7e
https://doi.org/10.1007/s40315-020-00350-9
https://doi.org/10.1007/s40315-020-00350-9
Autor:
Kelly Bickel, Pamela Gorkin
Publikováno v:
Complex Analysis and Spectral Theory. :241-261
The numerical range of a bounded, linear operator on a Hilbert space is a set in $\mathbb{C}$ that encodes important information about the operator. In this survey paper, we first consider numerical ranges of matrices and discuss several connections
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a0e976013a415b43daec0db75be86cbe
https://doi.org/10.1090/conm/743/14964
https://doi.org/10.1090/conm/743/14964
Publikováno v:
Transactions of the American Mathematical Society. 371:6213-6240
In this paper, we give necessary and sufficient conditions for weighted $L^2$ estimates with matrix-valued measures of well localized operators. Namely, we seek estimates of the form: \[ \| T(\mathbf{W} f)\|_{L^2(\mathbf{V})} \le C\|f\|_{L^2(\mathbf{
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::05a9889d9579bafbab88f443b14f0ca5
https://doi.org/10.1090/tran/7400
https://doi.org/10.1090/tran/7400
Autor:
Kelly Bickel, Constanze Liaw
Publikováno v:
Journal of Functional Analysis. 272:83-111
In this paper, we study operator-theoretic properties of the compressed shift operators $S_{z_1}$ and $S_{z_2}$ on complements of submodules of the Hardy space over the bidisk $H^2(\mathbb{D}^2)$. Specifically, we study Beurling-type submodules - nam
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::64e15c9c3c173741e19c1d7705975e27
https://doi.org/10.1016/j.jfa.2016.10.007
https://doi.org/10.1016/j.jfa.2016.10.007
Intuitively, an envelope of a family of curves is a curve that is tangent to a member of the family at each point. Here we use envelopes of families of circles to study objects from matrix theory and hyperbolic geometry. First we explore relationship
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5199d0faf7484ff75fb22c76f2877d07
Publikováno v:
Invariant Subspaces of the Shift Operator. :267-286
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::75a0630ff3af6be685821979d7110d9e
https://doi.org/10.1090/conm/638/12814
https://doi.org/10.1090/conm/638/12814
This paper generalizes the classical Sz.-Nagy--Foias $H^{\infty}(\mathbb{D})$ functional calculus for Hilbert space contractions. In particular, we replace the single contraction $T$ with a tuple $T=(T_1, \dots, T_d)$ of commuting bounded operators o
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::895763a3de1cc774761032b3dcbae985
http://arxiv.org/abs/1703.09677
http://arxiv.org/abs/1703.09677
Derivatives of rational inner functions: geometry of singularities and integrability at the boundary
We analyze the singularities of rational inner functions on the unit bidisk and study both when these functions belong to Dirichlet-type spaces and when their partial derivatives belong to Hardy spaces. We characterize derivative $H^{\mathfrak{p}}$ m
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::469500c73a61839e128886dfb0a617b1
Autor:
Kelly Bickel
Publikováno v:
Operators and Matrices. :71-90
Multivariable, real-valued functions induce matrix-valued functions defined on the space of d-tuples of n-times-n pairwise-commuting self-adjoint matrices. We examine the geometry of this space of matrices and conclude that the best notion of differe
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f2703f34f897ca5c3e758e7fad2913af
https://doi.org/10.7153/oam-07-03
https://doi.org/10.7153/oam-07-03