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For an arbitrary operator ideal I, every nilpotent element of I is a single commutator of operators from I^t, for an exponent t that depends on the degree of nilpotency.

Operator Algebras · Mathematics 2019-07-30 Ken Dykema , Amudhan Krishnaswamy-Usha

We show that under natural and quite general assumptions, a large part of a matrix for a bounded linear operator on a Hilbert space can be preassigned. The result is obtained in a more general setting of operator tuples leading to…

Functional Analysis · Mathematics 2023-11-10 Vladimir Müller , Yuri Tomilov

One-parameter semigroups of antitriangle idempotent supermatrices and corresponding superoperator semigroups are introduced and investigated. It is shown that $t$-linear idempotent superoperators and exponential superoperators are mutually…

Functional Analysis · Mathematics 2007-05-23 Steven Duplij

We study the class of those linear relations that can be factorized as products of idempotent relations. We provide several characterizations of this class, extending known factorization results for operators to the more general setting of…

Functional Analysis · Mathematics 2025-06-13 M. Laura Arias , Maximiliano Contino , Stefania Marcantognini

The main purpose is to introduce the so-called bicomplex (bc)-frames which is a special extension to bicomplex infinite Hilbert spaces of the classical frames. The crucial result is the characterization of bc-frames in terms of their…

Functional Analysis · Mathematics 2020-01-22 Aiad El Gourari , Allal Ghanmi , Mohammed Souid El Ainin

This article aims to explore the most recent developments in the study of the Hilbert matrix, acting as an operator on spaces of analytic functions and sequence spaces. We present the latest advances in this area, aiming to provide a…

Functional Analysis · Mathematics 2024-11-04 Carlo Bellavita , Vassilis Daskalogiannis , Georgios Stylogiannis

Operator matrices have played a significant role in studying Hilbert space operators. In this paper, we discuss further properties of operator matrices and present new estimates for the operator norms and numerical radii of such operators.…

Functional Analysis · Mathematics 2022-06-28 Fuad Kittaneh , Hamid Reza Moradi , Mohammad Sababheh

We establish necessary and sufficient conditions for the boundedness and compactness of weighted composition operators acting on weighted Dirichlet spaces and determine the spectrum of a certain class of such operators. Our results extend…

Functional Analysis · Mathematics 2026-02-10 Anirban Sen

We give a condition ensuring that the operators in a nilpotent Lie algebra of linear operators on a finite dimensional vector space have a common eigenvector.

Representation Theory · Mathematics 2007-05-23 Morris W. Hirsch , Joel W. Robbin

We study geometric properties of varieties associated with invariant subspaces of nilpotent operators. There are reductive algebraic groups acting on these varieties. We give dimensions of orbits of these actions. Moreover, a combinatorial…

Representation Theory · Mathematics 2019-06-27 Justyna Kosakowska , Markus Schmidmeier

Tom Leinster gave a bijective correspondence between the set of operators on a finite-dimensional vector space $V$ and the set of pairs consisting of a nilpotent operator and a vector in $V$. Over a finite field this bijection implies that…

Representation Theory · Mathematics 2025-12-04 Weixi Chen , Mee Seong Im , Mikhail Khovanov , Catherine Lillja , Nicolas Rugo

In this paper, we study the notion of a separability idempotent in the C*-algebra framework. This is analogous to the notion in the purely algebraic setting, typically considered in the case of (finite-dimensional) algebras with identity,…

Quantum Algebra · Mathematics 2017-09-26 Byung-Jay Kahng , Alfons Van Daele

A compatible nilpotent Leibniz algebra is a vector space equipped with two multiplication structures that interact in a certain natural way. This article presents the classification of these algebras with dimensions less than four, as well…

Rings and Algebras · Mathematics 2025-04-29 Ahmed Zahari Abdou , Kol Béatrice Gamou , Ibrahima Bakayoko

In this paper, we shall consider the notion of bicomplex inner product and define bicomplex Hilbert space. We shall define $L^{2}[a,b]$ where the functions take bicomplex values. We shall prove the Theorem for a bounded self adjoint…

Functional Analysis · Mathematics 2024-02-27 Akshay Sakharam Rane

Consider two non-degenerate algebras B and C over the complex numbers. We study a certain class of idempotent elements E in the multiplier algebra of the tensor product of B with C, called separability idempotents. The conditions include…

Rings and Algebras · Mathematics 2015-09-29 Alfons Van Daele

The aim of the present paper is, firstly we study the concepts of (m, (q_1, ..., q_d))- partial isometries on a Hilbert space, secondly, we introduce the notion of m- invertibility of tuples of operators as a natural generalization of the…

Functional Analysis · Mathematics 2016-03-01 Ould Ahmed Mahmoud Sid Ahmed

We develop the theory of the higher commutator for Taylor varieties. A new higher commutator operation called the hypercommutator is defined using a type of invariant relation called a higher dimensional congruence. The hypercommutator is…

Rings and Algebras · Mathematics 2020-08-04 Andrew Moorhead

Affiliated and normal operators in octonion Hilbert spaces are studied. Theorems about their properties and of related algebras are demonstrated. Spectra of unbounded normal operators are investigated.

Functional Analysis · Mathematics 2018-12-18 S. V. Ludkovsky

A new functional model for pairs of commuting isometries is described. Intertwining operators between such models are then studied in order to approach the classification of invariant subspaces of such pairs.

Spectral Theory · Mathematics 2008-05-27 H. Bercovici , R. G. Douglas , C. Foias

Our main theorem is in the generality of the axioms of Hilbert space, and the theory of unbounded operators. Consider two Hilbert spaces such that their intersection contains a fixed vector space D. It is of interest to make a precise…

Functional Analysis · Mathematics 2017-01-19 Palle Jorgensen , Erin Pearse , Feng Tian