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We establish new results on the $\mathcal I$-approximation property for the Banach operator ideal $\mathcal I=\mathcal{K}_{up}$ of the unconditionally $p$-compact operators in the case of $1\le p<2$. As a consequence of our results, we…

Functional Analysis · Mathematics 2023-10-09 Henrik Wirzenius

Applying a linearization theorem due to J. Mujica, we study the ideals of bounded holomorphic mappings $\mathcal{H}^\infty\circ\mathcal{I}$ generated by composition with an operator ideal $\mathcal{I}$. The bounded-holomorphic dual ideal of…

Functional Analysis · Mathematics 2023-02-10 M. G. Cabrera-Padilla , A. Jiménez-Vargas , D. Ruiz-Casternado

We consider the action of finitely truncated singular integral operators on functions taking values in a Banach space. Such operators are bounded for any Banach space, but we show a quantitative improvement over the trivial bound in any…

Functional Analysis · Mathematics 2023-10-16 Tuomas Hytönen

We study a notion analogous to the $p$-Approximation Property ($p$-AP) for Banach spaces, within the noncommutative context of operator spaces. Referred to as the $p$-Operator Approximation Property ($p$-OAP), this concept is linked to the…

Functional Analysis · Mathematics 2025-06-09 Javier Alejandro Chávez-Domínguez , Verónica Dimant , Daniel Galicer

We give necessary and sufficient conditions for a bounded operator defined between complex Hilbert spaces to be absolutely norm attaining. We discuss structure of such operators in the case of self-adjoint and normal operators separately.…

Spectral Theory · Mathematics 2018-01-09 G. Ramesh , D. Venku Naidu

Let T and C be two Hilbert space operators. We prove that if T is near, in a certain sense, to an operator completely polynomially dominated with a finite bound by C, then T is similar to an operator which is completely polynomially…

Functional Analysis · Mathematics 2007-05-23 C. Badea

We introduce the notion of (almost isometric) local retracts in metric space as a natural non-linear version of the concepts of locally complemented and almost isometric ideals from Banach spaces. We prove that given two metric spaces…

Functional Analysis · Mathematics 2023-11-23 Andrés Quilis , Abraham Rueda Zoca

Let $1 \leq p <\infty$. A sequence $\lef x_n \rig$ in a Banach space $X$ is defined to be $p$-operator summable if for each $\lef f_n \rig \in l^{w^*}_p(X^*)$, we have $\lef \lef f_n(x_k)\rig_k \rig_n \in l^s_p(l_p)$. Every norm…

Functional Analysis · Mathematics 2012-07-17 Anil Kumar Karn , Deba Prasad Sinha

We analyze various consequences in relation to the extension of operators $T:X\to Y$ that are $p$-compact, as well as the extension of operators $T:X\to Y$ whose adjoints $T^*:Y^*\to X^*$ are $p$-compact. In most cases, we discuss these…

Functional Analysis · Mathematics 2026-01-27 Sainik Karak , Tanmoy Paul

We derive novel concentration inequalities for the operator norm of the sum of self-adjoint operators that do not explicitly depend on the underlying dimension of the operator, but rather an intrinsic notion of it. Our analysis leads to…

Statistics Theory · Mathematics 2026-02-17 Diego Martinez-Taboada , Aaditya Ramdas

Indicial operators are model operators associated to an elliptic differential operator near a corner singularity on a stratified manifold. These model operators are defined on generalized tangent cone configurations and exhibit a natural…

Analysis of PDEs · Mathematics 2021-07-06 Thomas Krainer

It is well known that weakly $p$-summable sequences in a Banach space $E$ are associated to bounded operators from $\ell_{p^*}$ to $E$, and unconditionally $p$-summable sequences in $E$ are associated to compact operators from $\ell_{p^*}$…

Functional Analysis · Mathematics 2024-03-07 Geraldo Botelho , Ariel S. Santiago

Let $E, F, E_0$ be Banach spaces, with $E_0$ a subspace of $E$. For a maximal Banach operator ideal $\mathcal{A}$, we show that a linear operator from $E_0$ to $F$ can be extended to a linear operator from $E$ to $F$ that belongs to…

Functional Analysis · Mathematics 2025-06-19 Nahuel Albarracín , Pablo Turco

In recent years the coincidence of the operator relations equivalence after extension (EAE) and Schur coupling (SC) was settled for the Hilbert space case. For Banach space operators, it is known that SC implies EAE, but the converse…

Functional Analysis · Mathematics 2017-06-29 S. ter Horst , M. Messerschmidt , A. C. M. Ran , M. Roelands , M. Wortel

Given a conditional expectation $P$ from a C*-algebra $B$ onto a C*-subalgebra $A$, we observe that induction of ideals via $P$, together with a map which we call co-induction, forms a Galois connection between the lattices of ideals of $A$…

Operator Algebras · Mathematics 2025-11-04 Kevin Aguyar Brix , Chris Bruce , Kang Li , Eduardo Scarparo

Let A be a Banach algebra and let X be a Banach A -bimodule. In studying the bounded Hochschild cohomology groups H^1(A,X) it is often useful to extend a given derivation D: A-> X to a Banach algebra B containing A as an ideal, thereby…

Functional Analysis · Mathematics 2008-04-11 Niels Groenbaek

Stopping-time Banach spaces is a collective term for the class of spaces of eventually null integrable processes that are defined in terms of the behaviour of the stopping times with respect to some fixed filtration. From the point of view…

Functional Analysis · Mathematics 2022-08-29 Tomasz Kania , Richard Lechner

We systematize and generalize recent results of Gerlach and Gl\"uck on the strong convergence and spectral theory of bounded (positive) operator semigroups $(T_s)_{s\in S}$ on Banach spaces (lattices). (Here, $S$ can be an arbitrary…

Functional Analysis · Mathematics 2018-12-17 Jochen Glück , Markus Haase

Suppose $X$ and $Y$ are Banach spaces, and ${\mathcal{I}}$, ${\mathcal{J}}$ are operator ideals (for instance, the ideals of strictly singular, weakly compact, or compact operators). Under what conditions does the inclusion…

Operator Algebras · Mathematics 2013-09-24 T. Oikhberg , E. Spinu

A comprehensive analysis of Sobolev-type inequalities for the Ornstein-Uhlenbeck operator in the Gauss space is offered. A unified approach is proposed, providing one with criteria for their validity in the class of rearrangement-invariant…

Functional Analysis · Mathematics 2023-03-20 Andrea Cianchi , Vít Musil , Luboš Pick