8,913 research outputs found
The Dirichlet space: A Survey
In this paper we survey many results on the Dirichlet space of analytic
functions. Our focus is more on the classical Dirichlet space on the disc and
not the potential generalizations to other domains or several variables.
Additionally, we focus mainly on certain function theoretic properties of the
Dirichlet space and omit covering the interesting connections between this
space and operator theory. The results discussed in this survey show what is
known about the Dirichlet space and compares it with the related results for
the Hardy space.Comment: 35 pages, typoes corrected, some open problems adde
Supporting the active learning of collaborative database browsing techniques
We describe the implications of a study of database browsing behaviour for the development of a system to support more effective browsing. In particular we consider the importance of collaborative working, both in learning browsing skills and in co‐operating on a shared information‐retrieval task. From our study, we believe that an interface to support collaboration should promote the awareness of the activities of others, better visualization of the information data structures being browsed, and effective communication of the browsing process
The Corona Problem for Kernel Multiplier Algebras
We prove an alternate Toeplitz corona theorem for the algebras of pointwise
kernel multipliers of Besov-Sobolev spaces on the unit ball in
, and for the algebra of bounded analytic functions on certain
strictly pseudoconvex domains and polydiscs in higher dimensions as well. This
alternate Toeplitz corona theorem extends to more general Hilbert function
spaces where it does not require the complete Pick property. Instead, the
kernel functions of certain Hilbert function spaces
are assumed to be invertible multipliers on , and
then we continue a research thread begun by Agler and McCarthy in 1999, and
continued by Amar in 2003, and most recently by Trent and Wick in 2009. In
dimension we prove the corona theorem for the kernel multiplier algebras
of Besov-Sobolev Banach spaces in the unit disk, extending the result for
Hilbert spaces by A. Nicolau and J. Xiao.Comment: v1: 34 pages. v2: 34 pages, typos corrected. v3: 35 pages, typos
corrected, presentation improved. v4 35 pages, typos corrected and referee
comments included. v5 35 pages, additional reference added and remark to
prior related work include
The Hyt\"onen-Vuorinen L^{p} conjecture for the Hilbert transform when (4/3)<p<4 and the measures share no point masses
In the case (4/3)<p<4, and assuming a pair of locally finite positive Borel
measures on the real line have no common point masses, we prove two conjectures
of T. Hyt\"onen and E. Vuorinen from 2018 on two weight testing theorems for
the Hilbert transform on weighted L^{p} spaces. Namely, the two weight norm
inequality holds (1) if and only if the global quadratic interval testing
conditions hold, (2) if and only if the local quadratic interval testing, the
quadratic Muckenhoupt, and the quadratic weak boundedness conditions all hold.
We also give a slight improvement of the second conjecture in this setting by
replacing the quadratic Muckenhoupt conditions with two smaller conditions.Comment: 104 page
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