A. Zamani

activity

20142023

most citedSeminorm and numerical radius inequalities of operators in semi-Hilbertian spaces

79 citations · 247 across the 24 of their papers we have counts for

collaborators

32 papers

math.OA2023

$A$ -spectral permanence property for $C^{*}$ -algebras

Mohamed Mabrouk, Ali Zamani

For a positive element $A$ of a $C^{*}$ -algebra $A$ , let $∥ X ∥_{A}$ denote the $A$ -operator semi-norm of $X \in A$ . In this paper, we aim to introduce and stud…

math.OA2022

An extension of the $a$ -numerical radius on $C^{*}$ -algebras

Mohamed Mabrouk, Ali Zamani

Let $a$ be a positive element in a unital $C^{*}$ -algebra $A$ . We define a semi-norm on $A$ , which generalizes the $a$ -operator semi-norm and the $a$ -numerical…

math.FA2022★ 5 cited

An extension of Birkhoff--James orthogonality relations in semi-Hilbertian space operators

S. M. Enderami, M. Abtahi, A. Zamani

Let $B (H)$ denote the $C^{*}$ -algebra of all bounded linear operators on a Hilbert space $(H, ⟨ \cdot, \cdot ⟩)$ . Given a positive…

math.FA2022

A geometric approach to inequalities for the Hilbert--Schmidt norm

Ali Zamani

We define angle $Θ_{X, Y}$ between non-zero Hilbert--Schmidt operators $X$ and $Y$ by $cos Θ_{_{X, Y}} = \frac{Re Tr ( Y ^{*} X )}{∥ X ∥ _{_{2}} ∥ Y ∥ _{_{2}}}$ , and give some of it…

math.FA2022

An orthogonality relation in complex normed spaces based on norm derivatives

S. M. Enderami, M. Abtahi, A. Zamani +1

Let $X$ be a complex normed space. Based on the right norm derivative $ρ_{_{+}}$ , we define a mapping $ρ_{_{\infty}}$ by \begin{equation*} ρ_{_{\infty}}(x,y) = \frac1π\int_0^{2π}e^…

math.OA2021

Orthogonality Hilbert A-modules and operators preserving multi-A-linearity

Pawel Wojcik, Ali Zamani

In this paper we present results concerning orthogonality in Hilbert $C^{*}$ -modules. Moreover, for a $C^{*}$ -algebra $A$ , we prove theorems concerning the multi-$\mathscr{A}…

math.OA2021★ 1 cited

From norm derivatives to orthogonalities in Hilbert $C^{*}$ -modules

Pawel Wojcik, Ali Zamani

Let $(X, ⟨ \cdot, \cdot ⟩)$ be a Hilbert $C^{*}$ -module over a $C^{*}$ -algebra $A$ and let $S (A)$ be the set of states on $\ma…

math.FA2021★ 1 cited

The weighted Hilbert--Schmidt numerical radius

Ali Zamani

Let $B (H)$ be the algebra of all bounded linear operators on a Hilbert space $H$ and let $N (\cdot)$ be a norm on $B (H)$ . For every $…

math.FA2020

Some upper bounds for the $A$ -numerical radius of $2 \times 2$ block matrices

Qingxiang Xu, Zhongming Ye, Ali Zamani

Let $A = (A 0 0 A)$ be the $2 \times 2$ diagonal operator matrix determined by a positive bounded operator $A$ . For semi-H…

math.FA2020

On an extension of operator transforms

Ali Zamani

We introduce the $λ$ -mean transform $M_{λ} (T)$ of a Hilbert space operator $T$ as an extension of some operator transforms based on the Duggal transform $T^{D}$ by $M_λ(T) := λT + (1-λ…

math.FA2019

A-numerical radius and product of semi-Hilbertian operators

Ali Zamani

Let $A$ be a positive bounded operator on a Hilbert space $(H, ⟨ \cdot, \cdot ⟩)$ . The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\ra…

math.FA2019★ 79 cited

Seminorm and numerical radius inequalities of operators in semi-Hilbertian spaces

M. S. Moslehian, Q. Xu, A. Zamani

Let $A$ be a positive bounded operator on a Hilbert space $(H, ⟨ \cdot, \cdot ⟩)$ . The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\ra…

math.FA2019

Numerical radius orthogonality in $C^{*}$ -algebras

Ali Zamani, Pawel Wojcik

In this paper we characterize the Birkhoff--James orthogonality with respect to the numerical radius norm $v (\cdot)$ in $C^{*}$ -algebras. More precisely, for two elements $a, b$ in a…

math.FA2019★ 5 cited

Numerical radius inequalities concerning with algebraic norms

A. Zamani, M. S. Moslehian, Q. Xu +1

We give an expression for a generalized numerical radius of Hilbert space operators and then apply it to obtain upper and lower bounds for the generalized numerical radius. We also…

math.FA2019

$A$ -numerical radius inequalities for semi-Hilbertian space operators

Ali Zamani

Let $A$ be a positive bounded operator on a Hilbert space $(H, ⟨ \cdot, \cdot ⟩)$ . The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\ra…

math.FA2019★ 1 cited

Birkhoff--James orthogonality of operators in semi-Hilbertian spaces and its applications

Ali Zamani

In this paper, the concept of Birkhoff--James orthogonality of operators on a Hilbert space is generalized when a semi-inner product is considered. More precisely, for linear opera…

math.OA2018

Orthogonally $a$ -Jensen mappings on $C^{*}$ -modules

Ali Zamani

We investigate the representation of the so-called orthogonally $a$ -Jensen mappings acting on $C^{*}$ -modules. More precisely, let $A$ be a unital $C^{*}$ -algebra with the u…

math.FA2018★ 21 cited

Norm-parallelism and the Davis--Wielandt radius of Hilbert space operators

A. Zamani, M. S. Moslehian, M. T. Chien +1

We present a necessary and sufficient condition for the norm-parallelism of bounded linear operators on a Hilbert space. We also give a characterization of the Birkhoff--James orth…

math.FA2018

Numerical radius parallelism of Hilbert space operators

Marzieh Mehrazin, Maryam Amyari, Ali Zamani

In this paper, we introduce a new type of parallelism for bounded linear operators on a Hilbert space $(H, ⟨ \cdot, \cdot ⟩)$ based on numerical radiu…

math.FA2018

Characterizations of norm--parallelism in spaces of continuous functions

Ali Zamani

In this paper, we consider the characterization of norm--parallelism problem in some classical Banach spaces. In particular, for two continuous functions $f, g$ on a compact Hausdo…

math.OA2018★ 1 cited

Characterization of numerical radius parallelism in $C^{*}$ -algebras

Ali Zamani

Let $v (x)$ be the numerical radius of an element $x$ in a $C^{*}$ -algebra $A$ . First, we prove several numerical radius inequalities in $A$ . Particularly, we pr…

math.OA2017★ 2 cited

Orthogonality preserving property for pairs of operators on Hilbert $C^{*}$ -modules

Michael Frank, M. S. Moslehian, Ali Zamani

We investigate the orthogonality preserving property for pairs of mappings on inner product $C^{*}$ -modules extending existing results for a single orthogonality-preserving mapping.…

math.FA2017★ 11 cited

An extension of orthogonality relations based on norm derivatives

A. Zamani, M. S. Moslehian

We introduce the relation $ρ_{λ}$ -orthogonality in the setting of normed spaces as an extension of some orthogonality relations based on norm derivatives, and present some of its ess…

math.FA2017★ 3 cited

Approximately angle preserving mappings

Mohammad Sal Moslehian, Ali Zamani, Paweł Wójcik

In this paper, we present some characterizations of linear mappings, which preserve vectors at a specific angle. We introduce the concept of $(ε, c)$ -angle preserving map…

A-spectral permanence property for C∗-algebras

An extension of the a-numerical radius on C∗-algebras

An extension of Birkhoff--James orthogonality relations in semi-Hilbertian space operators

A geometric approach to inequalities for the Hilbert--Schmidt norm

An orthogonality relation in complex normed spaces based on norm derivatives

Orthogonality Hilbert A-modules and operators preserving multi-A-linearity

From norm derivatives to orthogonalities in Hilbert C∗-modules

The weighted Hilbert--Schmidt numerical radius

Some upper bounds for the A-numerical radius of 2×2 block matrices

On an extension of operator transforms

A-numerical radius and product of semi-Hilbertian operators

Seminorm and numerical radius inequalities of operators in semi-Hilbertian spaces

Numerical radius orthogonality in C∗-algebras

Numerical radius inequalities concerning with algebraic norms

A-numerical radius inequalities for semi-Hilbertian space operators

Birkhoff--James orthogonality of operators in semi-Hilbertian spaces and its applications

Orthogonally a-Jensen mappings on C∗-modules

Norm-parallelism and the Davis--Wielandt radius of Hilbert space operators

Numerical radius parallelism of Hilbert space operators

Characterizations of norm--parallelism in spaces of continuous functions

Characterization of numerical radius parallelism in C∗-algebras

Orthogonality preserving property for pairs of operators on Hilbert C∗-modules

An extension of orthogonality relations based on norm derivatives

Approximately angle preserving mappings

$A$ -spectral permanence property for $C^{*}$ -algebras

An extension of the $a$ -numerical radius on $C^{*}$ -algebras

From norm derivatives to orthogonalities in Hilbert $C^{*}$ -modules

Some upper bounds for the $A$ -numerical radius of $2 \times 2$ block matrices

Numerical radius orthogonality in $C^{*}$ -algebras

$A$ -numerical radius inequalities for semi-Hilbertian space operators

Orthogonally $a$ -Jensen mappings on $C^{*}$ -modules

Characterization of numerical radius parallelism in $C^{*}$ -algebras

Orthogonality preserving property for pairs of operators on Hilbert $C^{*}$ -modules