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We introduce and study twisted triangular Banach algebras T_sigma(A,B;X), built from Banach algebras A,B, a Banach A-B bimodule X, and a pair of automorphisms sigma=(sigma_A,sigma_B). This construction extends the classical triangular…

Functional Analysis · Mathematics 2025-10-07 Sara Behnamian , Fatemeh Fogh

We prove a very general theorem concerning the estimation of the expression $\|T(\frac{a+b}{2}) - \frac{Ta+Tb}{2}\|$ for different kinds of maps $T$ satisfying some general perurbated isometry condition. It can be seen as a quantitative…

Functional Analysis · Mathematics 2011-05-05 Rafal Gorak

We give a necessary and sufficient condition for amenability of the Banach algebra of approximable operators on a Banach space. We further investigate the relationship between amenability of this algebra and factorization of operators,…

Functional Analysis · Mathematics 2008-04-11 Ariel Blanco , Niels Groenbaek

We investigate the stability of Pexiderized mappings in Banach modules over a unital Banach algebra. As a consequence, we establish the Hyers--Ulam stability of the orthogonal Cauchy functional equation of Pexider type…

Functional Analysis · Mathematics 2021-07-23 Mohammad Sal Moslehian

The spaces $BV(\sigma)$ and $AC(\sigma)$ were introduced as part of a program to find a general theory which covers both well-bounded operators and trigonometrically well-bounded operators acting on a Banach space. Since their initial…

Functional Analysis · Mathematics 2023-05-29 Ian Doust , Michael Leinert , Alan Stoneham

Let $A$ be a commutative semisimple Arens regular unital Banach algebra. The correlation between the BSE-property of the Banach algebra $A$ and its second duals are assessed. It is found and approved that if $A$ is a BSE-algebra, then so is…

Functional Analysis · Mathematics 2022-01-19 Ali Rejali , Maryam Aghakoochaki

The convex-transitivity property can be seen as a convex generalization of the almost transitive (or quasi-isotropic) group action of the isometry group of a Banach space on its unit sphere. We will show that certain Banach algebras,…

Operator Algebras · Mathematics 2015-01-23 María J. Martín , Jarno Talponen

In this article, it is proved that a functional equation of (linear) Jordan triple derivations on unital Banach algebras under quite natural and simple assumptions is hyperstable. It is also shown that under some mild conditions approximate…

Functional Analysis · Mathematics 2015-06-10 Sang Og Kim , Abasalt Bodaghi

In this short note, we state a stable and a $\tau$-reduced version of the second Brauer-Thrall Conjecture. The former is a slight strengthening of a brick version of the second Brauer-Thrall Conjecture raised by Mousavand and…

Representation Theory · Mathematics 2023-08-21 Calvin Pfeifer

In this paper, we discuss the Hyers-Ulam stability of closable (unbounded) operators with several interesting examples. We also present results pertaining to the Hyers-Ulam stability of the sum and product of closable operators to have the…

Functional Analysis · Mathematics 2024-03-12 Arup Majumdar , P. Sam Johnson , Ram N. Mohapatra

We derive the complete and optimal Cheng--Yau gradient estimates and universal bounds for subcritical semilinear elliptic equations on Riemannian manifolds with (Bakry-\'{E}mery) Ricci curvature bounded below. This answers a fundamental…

Analysis of PDEs · Mathematics 2026-05-05 Zhihao Lu

In this paper, we present a study on the Ulam-Hyers and Ulam-Hyers-Rassias stabilities of the solution of the fractional functional differential equation using the Banach fixed point theorem.

Classical Analysis and ODEs · Mathematics 2018-07-18 J. Vanterler da C. Sousa , E. Capelas de Oliveira , F. G. Rodrigues

We establish the stability of second-order linear dynamic equations on time scales in the sense of Hyers and Ulam. To wit, if an approximate solution of the second-order linear equation exists, then there exists an exact solution to the…

Classical Analysis and ODEs · Mathematics 2013-06-26 Douglas R. Anderson

Motivated by $\tau$-tilting theory developed by Adachi, Iyama and Reiten, for a finite-dimensional algebra $\Lambda$ with action by a finite group $G$, we introduce the notion of $G$-stable support $\tau$-tilting modules. Then we establish…

Representation Theory · Mathematics 2016-07-26 Yingying Zhang , Zhaoyong Huang

We prove a commutative Gelfand--Naimark type theorem, by showing that the set $C_s(X)$ of continuous bounded (real or complex valued) functions with separable support on a locally separable metrizable space $X$ (provided with the supremum…

Functional Analysis · Mathematics 2015-06-26 M. R. Koushesh

It is easy to show that a pseudovariety which is reducible with respect to an implicit signature $\sigma$ for the equation $x=y$ can also be defined by $\sigma$-identities. We present several negative examples for the converse using…

Group Theory · Mathematics 2019-03-18 J. Almeida , O. Klíma

Since the main work on Ulam-Hyers dependable stabilities of differential equations to date, numerous significant and applicable papers have been published, both in the sense of integer order and fractional order differential equations.…

Classical Analysis and ODEs · Mathematics 2019-08-16 J. Vanterler da C. Sousa , K. D. Kucche , E. Capelas de Oliveira

Let $A$ be a unital separable non-elementary amenable simple stably finite C*-algebra such that its tracial state space has a $\sigma$-compact countable-dimensional extremal boundary. We show that $A$ is ${\cal Z}$-stable if and only if it…

Operator Algebras · Mathematics 2025-10-29 Huaxin Lin

Let $T$ be a Banach algebra homomorphism from a Banach algebra $\mathcal B$ to a Banach algebra $\mathcal A$ with $\|T\|\leq 1$. Recently it has been obtained some results about Arens regularity and also various notions of amenability of…

Functional Analysis · Mathematics 2015-02-19 F. Abtahi , A. Ghafarpanah , A. Rejali

We prove a structure theorem for stable functions on amenable groups, which extends the arithmetic regularity lemma for stable subsets of finite groups. Given a group $G$, a function $f\colon G\to [-1,1]$ is called stable if the binary…

Logic · Mathematics 2024-06-18 Gabriel Conant , Anand Pillay