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Motivated by noncommutative geometry and quantum physics, the concept of `metric operator field' is introduced. Roughly speaking, a metric operator field is a vector field on a set with values in self tensor product of a bundle of…

Operator Algebras · Mathematics 2019-07-31 Maysam Maysami Sadr

In view of the fact that some classical methods to construct multi-ideals fail in constructing hyper-ideals, in this paper we develop two new methods to construct hyper-ideals of multilinear operators between Banach spaces. These methods…

Functional Analysis · Mathematics 2015-11-11 Geraldo Botelho , Ewerton R. Torres

Given an operator ideal I, a Banach space E has the I-approximation property if operators on E can be uniformly approximated on compact subsets of E by operators belonging to I. In this paper the I- approximation property is studied in…

Functional Analysis · Mathematics 2010-09-16 Sonia Berrios , Geraldo Botelho

It is shown that each linear operator on a separable Hilbert space which generates a finite type I von Neumann algebra has, up to unitary equivalence, a unique representation as a direct integral of inflations of mutually unitary…

Functional Analysis · Mathematics 2017-05-26 Piotr Niemiec

For $p = 3,5,7,13$, we consider a ${\mathbb Z}_p$-orbifold construction of the Moonshine vertex operator algebra $V^\natural$. We show that the vertex operator algebra obtained by the ${\mathbb Z}_p$-orbifold construction on the Leech…

Quantum Algebra · Mathematics 2017-07-19 Toshiyuki Abe , Ching Hung Lam , Hiromichi Yamada

We show that there are $2^{2^{\aleph_0}}$ different closed ideals in the Banach algebra $L(L_p(0,1))$, $1<p\not= 2<\infty$. This solves a problem in A. Pietsch's 1978 book "Operator Ideals". The proof is quite different from other methods…

Functional Analysis · Mathematics 2021-02-12 William B. Johnson , Gideon Schechtman

We introduce asymptotic analogues of the Rademacher and martingale type and cotype of Banach spaces and operators acting on them. Some classical local theory results related, for example, to the `automatic-type' phenomenon, the type-cotype…

Functional Analysis · Mathematics 2018-11-20 Ryan M. Causey , Szymon Draga , Tomasz Kochanek

Using the notion of modulus of continuity at a point of a mapping between metric spaces, we introduce the notion of extensively bounded mappings generalizing that of Lipschitz mappings. We also introduce a metric on it which becomes a norm…

Functional Analysis · Mathematics 2025-01-06 Anil Kumar Karn , Arindam Mandal

We use the method of atomic decomposition and a new family of Banach spaces to study the action of transfer operators associated to piecewise-defined maps. It turns out that these transfer operators are quasi-compact even when the…

Dynamical Systems · Mathematics 2020-09-03 Alexander Arbieto , Daniel Smania

We show that the class of 1-exact operator systems is not uniformly definable by a sequence of types. We use this fact to show that there is no finitary version of Arveson's extension theorem. Next, we show that WEP is equivalent to a…

Operator Algebras · Mathematics 2015-12-22 Isaac Goldbring , Thomas Sinclair

We provide a concise proof of existence for nonlinear operator equations in separable Banach spaces. Notably, the operator is not assumed to be monotone. Instead, our main hypotheses consist of a continuity assumption and a generalized…

Analysis of PDEs · Mathematics 2025-03-21 Roland Becker , Malte Braack

In this paper, we characterize absolute norm-attainability for compact hyponormal operators. We give necessary and sufficient conditions for a bounded linear compact hyponormal operator on an infinite dimensional complex Hilbert space to be…

Functional Analysis · Mathematics 2019-03-29 Benard Okelo

We continue the study of multidimensional operator multipliers initiated in [arXiv:math/0701645]. We introduce the notion of the symbol of an operator multiplier. We characterise completely compact operator multipliers in terms of their…

Operator Algebras · Mathematics 2015-02-06 K. Juschenko , R. H. Levene , I. G. Todorov , L. Turowska

The theory of $\tau$-summing and $\sigma$-nuclear linear operators on Banach spaces was developed by Pietsch [12, Chapter 23]. Extending the linear case to the range p > 1 and generalizing all cases to the multilinear setting, in this paper…

Functional Analysis · Mathematics 2016-10-05 Geraldo Botelho , Ximena Mujica

We introduce and explore the concept of positive ideals for both linear and multilinear operators between Banach lattices. This paper delineates the fundamental principles of these new classes and provides techniques for constructing…

Functional Analysis · Mathematics 2024-08-27 Athmane Ferradi , Abdelaziz Belaada , Khalil Saadi

A wide new class of subsets of a Banach space $X$ named coarse $p$-limited sets ($ 1\leq p < \infty$) is introduced by considering weak* $p$-summable sequences in $X'$ instead of weak* null sequences. We study its basic properties and…

Functional Analysis · Mathematics 2021-08-11 Pablo Galindo , V. C. C. Miranda

We introduce the class of $\alpha$-firmly nonexpansive and quasi $\alpha$-firmly nonexpansive operators on $r$-uniformly convex Banach spaces. This extends the existing notion from Hilbert spaces, where $\alpha$-firmly nonexpansive…

Functional Analysis · Mathematics 2025-03-11 Arian Bërdëllima , Gabriele Steidl

In this paper we present part I of nonlinear operator ideals theory between metric spaces and Banach spaces. Building upon the definition of operator ideal between arbitrary Banach spaces of A. Pietsch we pose three types of nonlinear…

Functional Analysis · Mathematics 2015-07-06 Manaf Adnan Saleh Saleh

For each ordinal $0\leqslant \xi\leqslant \omega_1$, we introduce the notion of a $\xi$-completely continuous operator and prove that for each ordinal $0< \xi< \omega_1$, the class $\mathfrak{V}_\xi$ of $\xi$-completely continuous operators…

Functional Analysis · Mathematics 2018-03-28 R. M. Causey , K. Navoyan

We study the universal approximation properties of transformers and neural integral operators for operators in Banach spaces. In particular, we show that the transformer architecture is a universal approximator of integral operators between…

Machine Learning · Computer Science 2026-04-28 Emanuele Zappala , Maryam Bagherian