11 citations · 12 across the 17 of their papers we have counts for
20 papers
Operator Geometry of Hilbert Ball Automorphisms
Saikat Roy
We consider the operator--theoretic model for the group of biholomorphic automorphisms of the unit ball of a complex Hilbert space $\H$ by representing each automorphi…
Norming Approximate Orthogonality in Normed Linear Spaces
Saikat Roy
We introduce and study the notion of \emph{norming approximate orthogonality}, a two-parameter generalization of Birkhoff--James orthogonality in normed linear spaces. For $δ, \var…
Polyhedral norms and smooth Hahn-Banach extension
Saikat Roy
We find a necessary and sufficient condition for a smooth functional on a subspace to admit a norm-preserving smooth extension to the entire space in polyhedral norms. The characte…
A characterization of Banach spaces with numerical index one
Subhadip Pal, Saikat Roy, Debmalya Sain
We investigate the extremal properties of the unit ball of , the dual space of bounded linear operators defined on a Banach space equipped with the numerical radius n…
Distance and best approximations in operator norm and trace class norm
Saikat Roy
We study the best approximation and distance problems in the operator space $\B(\HS)$ and in the space of trace class operators $\LS^1(\B(\HS))$. Formulations of distances are obta…
A unified approach to a family of optimization problems in Banach spaces
Kallol Paul, Saikat Roy, Debmalya Sain +1
Our principal aim is to illustrate that the concept Birkhoff-James orthogonality can be applied effectively to obtain a unified approach to a large family of optimization problems…
Orthogonality of bilinear forms and application to matrices
Saikat Roy, Tanusri Senapati, Debmalya Sain
We characterize Birkhoff-James orthogonality of continuous vector-valued functions on a compact topological space. As an application of our investigation, Birkhoff-James orthogonal…
A dilation theoretic approach to Banach spaces
Swapan Jana, Sourav Pal, Saikat Roy
For a complex Banach space , we prove that is a Hilbert space if and only if every strict contraction on dilates to an isometry if and only i…
Dilation and Birkhoff-James orthogonality
Sourav Pal, Saikat Roy
We study the interaction between unitary -dilations of a pair of Hilbert space operators and Birkhoff-James orthogonality. We prove that for two orthogonal operators if $\…
A numerical range approach to Birkhoff-James orthogonality with applications
Miguel Martin, Javier Meri, Alicia Quero +2
The main aim of this paper is to provide characterizations of Birkhoff-James orthogonality (BJ-orthogonality in short) in a number of families of Banach spaces in terms of the elem…
Birkhoff-James Orthogonality and Its Local Symmetry in Some Sequence Spaces
Babhrubahan Bose, Saikat Roy, Debmalya Sain
We study Birkhoff-James orthogonality and its local symmetry in some sequence spaces namely for , , , and . Using the characte…
The Weak differentiability of norm and a generalized Bhatia-Šemrl Theorem
Saikat Roy
We completely characterize the weak differentiability (or, in other words Gateaux differentiability) of the norm in the spaces of bounded multilinear maps. Also, we obtain a multil…
Birkhoff-James orthogonality in complex Banach spaces and Bhatia-Šemrl Theorem revisited
Saikat Roy, Satya Bagchi, Debmalya Sain
We explore Birkhoff-James orthogonality of two elements in a complex Banach space by using the directional approach. Our investigation illustrates the geometric distinctions betwee…
Numerical radius and a notion of smoothness in the space of bounded linear operators
Saikat Roy, Debmalya Sain
We observe that the classical notion of numerical radius gives rise to a notion of smoothness in the space of bounded linear operators on certain Banach spaces, whenever the numeri…
On best approximations in Banach spaces from the perspective of orthogonality
Debmalya Sain, Saikat Roy
We study best approximations in Banach spaces via Birkhoff-James orthogonality of functionals. To exhibit the usefulness of Birkhoff-James orthogonality techniques in the study of…
Geometry of nowhere vanishing, point separating sub-algebras of and zeros of Holomorphic functions
Babhrubahan Bose, Saikat Roy, Debmalya Sain
We study , the normed algebra of all holomorphic functions defined on some simply connected neighbourhood of a simple closed curve in $\mat…
Orthogonality in a vector space with a topology And a generalization of Bhatia-Semrl Theorem
Debmalya Sain, Saikat Roy, Kallol Paul
We introduce the notion of orthogonality in a vector space with a topology on it. To serve our purpose, we define orthogonality space for a given vector space X, using the topology…
A study of symmetric points in Banach spaces
Debmalya Sain, Saikat Roy, Satya Bagchi +1
We completely characterize the left-symmetric points, the right-symmetric points, and, the symmetric points in the sense of Birkhoff-James, in a Banach space. We obtain a complete…
Extreme contractions on finite-dimensional polygonal Banach spaces-II
Anubhab Ray, Saikat Roy, Satya Bagchi +1
We introduce the concept of weak L-P property for a pair of Banach spaces, in the study of extreme contractions. We give examples of pairs of Banach spaces (not) satisfying weak L-…
On maximum distance separable group codes with complementary duals
Saikat Roy, Satya Bagchi
Given an LCD group code in a group algebra , we inspect kinship between and , more precisely between the subgroup structures of and . Under some special circu…