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In this paper, a generalized Cauchy-Schwarz inequality for positive sesquilinear maps with values in noncommutative Lp-spaces for p > 1 are obtained. Bound estimates for their real and imaginary parts are also provided, and, as an…

Operator Algebras · Mathematics 2026-02-13 Giorgia Bellomonte , Stefan Ivkovic , Camillo Trapani

We prove a weak-type (1, 1) inequality involving conditioned versions of square functions for martingales in noncommutative $L^p$-spaces associated with finite von Neumann algebras. As application, we determine the optimal orders for the…

Operator Algebras · Mathematics 2011-11-09 Narcisse Randrianantoanina

We characterize classes of linear maps between operator spaces $E$, $F$ which factorize through maps arising in a natural manner via the Pisier vector-valued non-commutative $L^p$ spaces $S_p[E^*]$ based on the Schatten classes on the…

funct-an · Mathematics 2008-02-03 Francesco Fidaleo

We consider a positive operator $A$ on a Hilbert lattice such that its self-commutator $C = A^* A - A A^*$ is positive. If $A$ is also idempotent, then it is an orthogonal projection, and so $C = 0$. Similarly, if $A$ is power compact, then…

Functional Analysis · Mathematics 2025-01-08 Roman Drnovšek , Marko Kandić

We prove a basic inequality involving anticommutators in noncommutative $L_p$-spaces. We use it to complete our study of the noncommutative Mazur maps from $L_p$ to $L_q$ showing that they are Lipschitz on balls when $0<q<p<\infty$.

Functional Analysis · Mathematics 2020-12-07 Eric Ricard

Power nonnegative matrices are defined as complex matrices having at least one nonnegative integer power. We exploit the possibility of deriving a Perron Frobenius-like theory for these matrices, obtaining three main results and drawing…

Numerical Analysis · Mathematics 2013-11-21 F. Tudisco , V. Cardinali , C. Di Fiore

We consider linear operators defined on a subspace of a complex Banach space into its topological antidual acting positively in a natural sense. The goal of this paper is to investigate of this kind of operators. The main theorem is a…

Functional Analysis · Mathematics 2014-09-12 Zoltán Sebestyén , Zsolt Szűcs , Zsigmond Tarcsay

We show that the validity of the non-commutative Khintchine inequality for some $q$ with $1<q<2$ implies its validity (with another constant) for all $1\le p<q$. We prove this for the inequality involving the Rademacher functions, but also…

Operator Algebras · Mathematics 2014-12-23 Gilles Pisier

We study a nonlinear analogue of additive commutators, known as \textit{polynomial commutators}, defined by $p(ab) - p(ba)$ for a polynomial $p \in F[x]$ and elements $a, b$ in an algebra $R$ over a field $F$. Originally introduced by…

Rings and Algebras · Mathematics 2026-03-18 Truong Huu Dung , Tran Nam Son , Pham Duy Vinh

In this paper, we provide a representation of a certain class of C*-valued positive sesquilinear and linear maps on non-unital quasi *-algebras. Also, we illustrate our results on the concrete examples of non-unital Banach quasi *-algebras,…

Operator Algebras · Mathematics 2024-09-10 Stefan Ivkovic , Bogdan D. Djordjevic , Giorgia Bellomonte

We introduce and systematically develop the theory of \emph{quantum doubly stochastic operators}, i.e. positive, trace-preserving maps on non-commutative $L_p$-spaces associated to semifinite von Neumann algebras. After establishing basic…

Operator Algebras · Mathematics 2026-05-19 Emma Sulaver

We construct a Schauder basis for $L_1$ consisting of non-negative functions and investigate unconditionally basic and quasibasic sequences of non-negative functions in $L_p$, $1\le p < \infty$.

Functional Analysis · Mathematics 2015-02-27 William B. Johnson , Gideon Schechtman

In this article we give a counter-example on the statement of a theorem appearing in a note $[3]$ of A. Brunel concerning the study of positive operators on the the spaces $L_p\,\,(1<p<\infty)$ which the sequence of the powers is…

Dynamical Systems · Mathematics 2013-06-12 Jean-Claude Lootgieter

In this paper necessary conditions and sufficient conditions are given for a linear operator to be a positive operators of an Extended Lorentz cone. Similarities and differences with the positive operators of Lorentz cones are investigated.

Optimization and Control · Mathematics 2016-08-30 S. Z. Németh , G. Zhang

The operators on $\ell_{\infty}$ which are commutators are those not of the form $\lambda I + S$ with $\lambda\neq 0$ and $S$ strictly singular.

Functional Analysis · Mathematics 2009-07-27 Detelin Dosev , William B. Johnson

We consider linear bounded operators acting in Banach spaces with a basis, such operators can be represented by an infinite matrix. We prove that for an invertible operator there exists a sequence of invertible finite-dimensional operators…

Functional Analysis · Mathematics 2024-03-12 Alexander Vasilyev , Vladimir Vasilyev , Abu Bakarr Kamanda Bongay

Representations of polynomial covariant type commutation relations by pairs of linear integral operators and multiplication operators on Banach spaces $L_p$ are constructed.

Functional Analysis · Mathematics 2023-05-18 Domingos Djinja , Sergei Silvestrov , Alex Behakanira Tumwesigye

This paper investigates spectral properties of certain classes of positive operators originated from different matrices appeared in linear complementarity problem. These positive operators play a crucial role in various areas of mathematics…

Functional Analysis · Mathematics 2025-02-25 Rashid A. , P Sam Johnson

Extending the corresponding notion for matrices or bounded linear operators on a Hilbert space we define a generalized Schur complement for a non-negative linear operator mapping a linear space into its dual and derive some of its…

Functional Analysis · Mathematics 2018-07-18 J. Friedrich , M. Günther , L. Klotz

Let $T$ be a bounded linear operator on a (real or complex) Banach space $X$. If $(a_n)$ is a sequence of non-negative numbers tending to 0. Then, the set of $x \in X$ such that $\|T^nx\| \geqslant a_n \|T^n\|$ for infinitely many $n$'s has…

Functional Analysis · Mathematics 2012-04-11 Jean-Matthieu Augé