19 papers
On the shape of the numerical range of some tridiagonal matrices
Arobinda Ghosh, Riddhick Birbonshi, Sarita Ojha +1
In this paper, we study the elliptical shape of the numerical range of tridiagonal matrices of orders and with zero entries on the main diagonal, a positive constant valu…
Numerical range and invariant subspaces of weighted composition operators on the Hardy space of Dirichlet series
Sudeshna Lahiri, Sarita Ojha, Subhadip Halder +1
In this paper, we study various results on numerical range of weighted composition operators on Hardy space of Dirichlet series. Certain conditions are provided under which the num…
-Berezin sectorial operators with applications to -Berezin number inequalities and -Berezin ranges
Saikat Mahapatra, Subhadip Halder, Riddhick Birbonshi +2
In this paper, we introduce a new class of operators, called -Berezin sectorial operators, as an extension of the class of -sectorial operators. By presenting examples on the…
On the numerical radius of a class of weighted shift operators
Arobinda Ghosh, Riddhick Birbonshi, Sarita Ojha
In this paper, we derive some bounds on numerical radius of the weighted shift operator with weights where and . Furt…
Improved upper bounds for the Berezin numbers of operators on reproducing kernel Hilbert spaces
Riddhick Birbonshi, Sumon Ghosh, Fuad Kittaneh +2
In this article, several upper bounds for the Berezin numbers of bounded linear operators on reproducing kernel Hilbert spaces are obtained through the use of interpolation paths o…
Improved Bounds for numerical radius and -numerical radius in -algebras
Saikat Mahapatra, Arobinda Ghosh, Riddhick Birbonshi
In this article, we derive several significant upper bounds for the numerical radius and -numerical radius of an element in a -algebra by improving inequalities for posit…
On posinormality of weighted composition-differentiation operators on
Gour Hait, Sarita Ojha, Nirupam Ghosh +1
In this article, the posinormality and coposinormality of weighted composition-differentiation operators on Hardy space are investigated. It is observed that whil…
Iterated Aluthge transforms of some composition operators on weighted Bergman spaces
Sudeshna Lahiri, Sarita Ojha, Riddhick Birbonshi
In this paper, we compute the iterated Aluthge transforms of the composition operator on the weighted Bergman spaces , wh…
An introduction of Berezin sectorial operators and its application to Berezin number inequalities
Saikat Mahapatra, Sweta Mukherjee, Anirban Sen +2
We introduce a new class of operators, called Berezin sectorial operators, which generalizes classical sectorial operators. We provide examples on the Hardy-Hilbert space showing t…
A note on weighted composition operators on Dirichlet space
Subhadip Halder, Sweta Mukherjee, Riddhick Birbonshi
In this paper, we provide some sufficient conditions for the compactness of weighted composition operators on Dirichlet space. Furthermore, we characterize the numerical range of c…
Berezin number and Berezin norm inequalities via Moore-Penrose inverse
Saikat Mahapatra, Anirban Sen, Riddhick Birbonshi +1
In this article, we establish the Berezin number and Berezin norm inequalities for bounded linear operators on a reproducing kernel Hilbert space using the Moore-Penrose inverse. T…
Numerical range of Toeplitz and Composition operators on weighted Bergman spaces
Anirban Sen, Subhadip Halder, Riddhick Birbonshi +1
In this paper we completely describe the numerical range of Toeplitz operators on weighted Bergman spaces with harmonic symbol. We also characterize the numerical range of weighted…
On the --Numerical Range of Operators in Semi-Hilbertian Spaces
Jyoti Rani, Arnab Patra, Riddhick Birbonshi
This study investigates the --numerical range of an operator within the framework of semi-Hilbertian spaces. Several fundamental properties of the --numerical range are…
Upper bounds of numerical radius and -numerical radius in -algebra setting using Orlicz functions
Saikat Mahapatra, Riddhick Birbonshi, Arnab Patra
In this paper, several significant upper bounds for the numerical radius and -numerical radius of an element in a -algebra are obtained using Orlicz functions. Ma…
A note on the -numerical range of semi-Hilbertian operators
Anirban Sen, Riddhick Birbonshi, Kallol Paul
In this paper we explore the relation between the -numerical range and the -spectrum of -bounded operators in the setting of semi-Hilbertian structure. We introduce a new…
On some study of the fine spectra of generalized difference operator on
Riddhick Birbonshi, Arnab Patra, P. D. Srivastava
In this paper, we determine the spectrum, the point spectrum, the continuous spectrum and the residual spectrum of the generalized difference operator on the sequence spa…
A note on Anderson's theorem in the infinite-dimensional setting
Riddhick Birbonshi, Ilya M. Spitkovsky, P. D. Srivastava
Anderson's theorem states that if the numerical range W(A) of an n-by-n matrix A is contained in the unit disk and intersects with the unit circle at more than n points, then it co…
On the boundary of the numerical range of some Jacobi operators
R. Birbonshi, A. Patra, P. D. Srivastava
In this paper, we study the numerical range of Jacobi operators and it is shown that under certain conditions, the boundary of the numerical range of these operators can be non-rou…
On some study of the Fine Spectra of -th band triangular matrices
R. Birbonshi, P. D. Srivastava
It has been observed that for the 2nd and 3rd band lower triangular matrices and , only the boundary of the spectrum gives the continuous spectrum while the rest…