3 papers
math.FA2025
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…
math.FA2018
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…
math.FA2017
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…