8 papers
On the -numerical radius of rank-one operators and parametrized Buzano-type inequalities
Hranislav Stanković
Let be a complex Hilbert space and . We establish the explicit formula \[ ω_ρ(a\otimes b)=\frac{1}ρ\|a\| \|b\|+\left|1-\frac{1}ρ\right||\langle a,b\rangle|,\qqua…
Normaloid Operators and the Root Problem
B. P. Duggal, C. S. Kubrusly, H. M. Stankovic
The paper extends previous results on the nth root problem to a large class of Hilbert-space operators, namely, the class of all normaloid operators with normaloid parts, which inc…
On the ascent and the angle between the null space and the range of elementary operators
Janko Bračič, Bojan Kuzma, Hranislav Stanković
We study the angle between the null space and the range of elementary operators of length one or two acting on , the Banach algebra of all bounded linear…
Structural Properties and Normality Criteria for Subclasses of Normaloid Operators
Hranislav Stanković, Carlos Kubrusly
We investigate structural properties and normality criteria for certain classes of bounded linear operators on a Hilbert space. We show that an operator with polar decompositio…
On inequalities involving the spherical operator transforms
Fuad Kittaneh, Satyajit Sahoo, Hranislav Stanković
This paper explores refinements of some operator norm inequalities through the generalized spherical Aluthge transform and the spherical Heinz transform. We introduce the spherical…
Birkhoff-James orthogonality: A Minimax Theorem approach
Hranislav Stanković
In this paper, we present an elementary proof of the Bhatia-Šemrl Theorem, utilizing the Minimax Theorem for bounded linear operators by Asplund and Ptak [1]. Some related results…
Characterizations of positive operators via their powers
Hranislav Stanković
In this paper, we present new characterizations of normal and positive operators in terms of their powers. Among other things, we show that if is normal, $\mathcal{W}(T^{2k+1…
-numerical radius of rank-one operators and the generalized Buzano inequality
Dušan Denčić, Hranislav Stanković, Mihailo Krstić +1
Here, we study the -numerical radius of rank-one operators on a Hilbert space . More precisely, for and , we establish the formu…