Saikat Roy

collaborators

7 papers

math.FA2026

Operator Geometry of Hilbert Ball Automorphisms

Saikat Roy

We consider the operator--theoretic model for the group of biholomorphic automorphisms $A u t (B)$ of the unit ball $B$ of a complex Hilbert space $\H$ by representing each automorphi…

math.FA2026

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 $Î´, \va…

math.FA2026

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…

math.FA2026

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 $L (X)_{w}^{*}$ , the dual space of bounded linear operators defined on a Banach space $X$ equipped with the numerical radius n…

math.FA2025

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…

math.FA2025

A dilation theoretic approach to Banach spaces

Swapan Jana, Sourav Pal, Saikat Roy

For a complex Banach space $X$ , we prove that $X$ is a Hilbert space if and only if every strict contraction $T$ on $X$ dilates to an isometry if and only i…