64 citations · 883 across the 94 of their papers we have counts for
11 papers · 2 filters
Orthogonality induced by norm derivatives : A new geometric constant and symmetry
Souvik Ghosh, Kallol Paul, Debmalya Sain
In this article we study the difference between orthogonality induced by the norm derivatives (known as -orthogonality) and Birkhoff-James orthogonality in a normed linear space…
-Davis-Wielandt Radius Bounds of Semi-Hilbertian Space Operators
Messaoud Guesba, Somdatta Barik, Pintu Bhunia +1
Consider is a complex Hilbert space and is a positive operator on The mapping $\langle\cdot,\cdot\rangle_A: \mathcal{H}\times \mathcal{H} \to \math…
On the best coapproximation problem in
Debmalya Sain, Shamim Sohel, Souvik Ghosh +1
We study the best coapproximation problem in the Banach space by using Birkhoff-James orthogonality techniques. Given a subspace of , we comple…
On best coapproximations in subspaces of diagonal matrices
Debmalya Sain, Shamim Sohel, Souvik Ghosh +1
We characterize the best coapproximation(s) to a given matrix out of a given subspace of the space of diagonal matrices , by using Birkhoff-Ja…
On k-smoothness of operators between Banach spaces
Debmalya Sain, Shamim Sohel, Kallol Paul
We explore the -smoothness of bounded linear operators between Banach spaces, using the newly introduced notion of index of smoothness. The characterization of the -smoothnes…
On isosceles orthogonality and some geometric constants in a normed space
Debmalya Sain, Souvik Ghosh, Kallol Paul
We study the James constant , an important geometric quantity associated with a normed space , and explore its connection with isosceles orthogonality…
On some special subspaces of a Banach space, from the perspective of best coapproximation
Shamim Sohel, Souvik Ghosh, Debmalya Sain +1
We study the best coapproximation problem in Banach spaces, by using Birkhoff-James orthogonality techniques. We introduce two special types of subspaces, christened the anti-copro…
On local preservation of orthogonality and its application to isometries
Debmalya Sain, Jayanta Manna, Kallol Paul
We investigate the local preservation of Birkhoff-James orthogonality at a point by a linear operator on a finite-dimensional Banach space and illustrate its importance in understa…
On uniform Bishop-Phelps-Bollobás type approximations of linear operators and preservation of geometric properties
Debmalya Sain, Arpita Mal, Kalidas Mandal +1
We study uniform BPB approximations of bounded linear operators between Banach spaces from a geometric perspective. We show that for sufficiently small positive values of …
Extreme contractions on finite-dimensional Banach spaces
Debmalya Sain, Shamim Sohel, Kallol Paul
We study extreme contractions in the setting of finite-dimensional polyhedral Banach spaces. Motivated by the famous Krein-Milman Theorem, we prove that a \emph{rank one} norm one…
On T-orthogonality in Banach spaces
Debmalya Sain, Souvik Ghosh, Kallol Paul
Let be a Banach space and let be the dual space of For is said to be -orthogonal to if where…