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We prove a weak-type estimate for a class of operators extending some of the almost orthogonality issues involved in the study of the bilinear Hilbert transform by Lacey and Thiele.

Classical Analysis and ODEs · Mathematics 2007-05-23 Jose Barrionuevo , Michael T. Lacey

Devoted to multi-task learning and structured output learning, operator-valued kernels provide a flexible tool to build vector-valued functions in the context of Reproducing Kernel Hilbert Spaces. To scale up these methods, we extend the…

Machine Learning · Computer Science 2018-05-25 Romain Brault , Florence d'Alché-Buc , Markus Heinonen

We prove that a Banach space has the uniform approximation property with proportional growth of the uniformity function iff it is a weak Hilbert space.

Functional Analysis · Mathematics 2008-02-03 William B. Johnson , Gilles Pisier

Motivated by a seminal paper of professor M. Z. Nashed published in 1987 on classification of ill-posed linear operator equations and distinguishing two types of ill-posedness in Banach and Hilbert spaces, we present, illustrate and justify…

Functional Analysis · Mathematics 2025-11-11 Jens Flemming , Bernd Hofmann

We introduce the notion of an ACF space, that is, a space for which a generalized version of M. Riesz's theorem for conjugate functions with values in the Banach space is bounded. We use transference to prove that spaces for which the…

Functional Analysis · Mathematics 2008-02-03 N. Asmar , B. Kelly , Stephen J. Montgomery-Smith

In this paper, the weighted estimates for multilinear pseudo-differential operators were systematically studied in rearrangement invariant Banach and quasi-Banach spaces. These spaces contain the Lebesgue space, the classical Lorentz space…

Classical Analysis and ODEs · Mathematics 2023-12-21 Jiawei Tan , Qingying Xue

A closed subspace of a Banach space $\cX$ is almost-invariant for a collection $\cS$ of bounded linear operators on $\cX$ if for each $T \in \cS$ there exists a finite-dimensional subspace $\cF_T$ of $\cX$ such that $T \cY \subseteq \cY +…

Functional Analysis · Mathematics 2012-04-23 Laurent W. Marcoux , Alexey I. Popov , Heydar Radjavi

Very recently, motivated by the result of Bhatia and \v{S}emrl which characterizes the Birkhoff-James orthogonality of operators on a finite dimensional Hilbert space in terms of norm attaining points, the Bhatia-\v{S}emrl property was…

Functional Analysis · Mathematics 2021-05-04 Geunsu Choi , Sun Kwang Kim

We give a characterization of the two-weight inequality for a simple vector-valued operator. Special cases of our result have been considered before in the form of the weighted Carleson embedding theorem, the dyadic positive operators of…

Classical Analysis and ODEs · Mathematics 2013-04-02 James Scurry

We develop a theory of Hilbert-space valued stochastic integration with respect to cylindrical martingale-valued measures. As part of our construction, we expand the concept of quadratic variation, introduced by Veraar and Yaroslavtsev…

Probability · Mathematics 2025-06-17 Santiago Cambronero , David Campos , C. A. Fonseca-Mora , Darío Mena

It is well known that under certain conditions on a Banach space $X$, the set of bounded linear operators attaining their numerical radius is a dense subset. We prove in this paper that if $X$ is assumed to be uniformly convex and uniformly…

Functional Analysis · Mathematics 2023-02-28 Mohammed Bachir

Given any finite quiver, we consider a complete flag of vector spaces over each vertex. Consider the unipotent invariant subalgebra of the coordinate ring of the filtered quiver representation subspace. We prove that the dimension of the…

Algebraic Geometry · Mathematics 2016-09-27 Mee Seong Im , Lisa M. Jones

In this note, we consider discriminant forms that are given by the norm form of real quadratic fields and their induced Weil representations. We prove that there exists an isomorphism between the space of vector-valued modular forms for the…

Number Theory · Mathematics 2014-01-16 Yichao Zhang

Henstock-type integrals are considered, for multifunctions taking values in the family of weakly compact and convex subsets of a Banach lattice $X$. The main tool to handle the multivalued case is a R{\aa}dstr\"om-type embedding theorem…

Functional Analysis · Mathematics 2015-10-20 Antonio Boccuto , Domenico Candeloro , Anna Rita Sambucini

Let T be a Cowen-Douglas tuple on a Banach space X. We use functional representations of T to associate with each T-invariant subspace Y of X an integer called the fiber dimension of Y. Among other results we prove a limit formula for the…

Functional Analysis · Mathematics 2016-01-12 Jörg Eschmeier , Sebastian Langendörfer

Let $X$ be a ball quasi-Banach function space on ${\mathbb R}^n$. In this article, the authors introduce the weak Hardy-type space $WH_X({\mathbb R}^n)$, associated with $X$, via the radial maximal function. Assuming that the powered…

Classical Analysis and ODEs · Mathematics 2019-07-01 Yangyang Zhang , Songbai Wang , Dachun Yang , Wen Yuan

The theory of multiplier modules of Hilbert C*-modules is reconsidered to obtain more properties of these special Hilbert C*-modules. The property of a Hilbert C*-module to be a multiplier C*-module is shown to be an invariant with respect…

Operator Algebras · Mathematics 2026-03-26 Michael Frank

This paper is about the connection between certain Banach-algebraic properties of a commutative Banach algebra $E$ with unit and the associated commutative Banach algebra $C(X,E)$ of all continuous functions from a compact Hausdorff space…

Functional Analysis · Mathematics 2016-01-25 Azadeh Nikou , Anthony G. O'Farrell

We consider iterated function systems (finite or countable), together with linear and continuous operators on Hilbert spaces, which enable us to construct Markov-type operators. Under suitable conditions, these Markov-type operators have…

Classical Analysis and ODEs · Mathematics 2017-01-30 Ion Chiţescu , Loredana Ioana , Radu Miculescu , Lucian Niţă

The abscissas of convergence, uniform convergence and absolute convergence of vector valued Dirichlet series with respect to the original topology and with respect to the weak topology $\sigma(X,X')$ of a locally convex space $X$, in…

Functional Analysis · Mathematics 2015-02-03 José Bonet