Shubhankar Mandal

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20212026

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6 papers · 1 filter

math.FA2026

Failure of Rational Dilation on the Tetrablock via Parrott Homomorphisms

Shubhankar Mandal, Samya Kumar Ray

We determine the cotangent operator space structure at the origin of the tetrablock (denoted by $E$ ). In particular we prove that $\operatorname{COT}_0(\overline{\mathbb E}…

math.FA2025

Functional models for $Γ_{n}$ -contractions

Shubhankar Mandal, Avijit Pal, Bhaskar Paul

This article develops several functional models for a given $Γ_{n}$ -contraction. The first model is motivated by the Douglas functional model for a contraction. We then establish fac…

math.FA2025

Few maps in the rich structure for the domains $G_{E (3; 3; 1, 1, 1)}$ and $G_{E (3; 2; 1, 2)}$

Dinesh Kumar Keshari, Shubhankar Mandal, Avijit Pal

The primary goal of a rich structure for some naturally occurring domains $X$ is to connect four naturally occurring objects of analysis in the context of $3 \times 3$ anal…

math.FA2025

Function Theory and necessary conditions for a Schwarz lemma related to $μ$ -Synthesis Domains

Dinesh Kumar Keshari, Shubhankar Mandal, Avijit Pal

A subset of $C^{7}$ (respectively, of $C^{5}$ ) associated with the structured singular value $μ_{E}$ , defined on $3 \times 3$ matrices, is denoted by $G_{E (3; 3; 1, 1, 1)}$ …

math.FA2025

Unitary equivalence of balanced weighted shifts on rooted directed trees

Shubhankar Mandal, Shailesh Trivedi

We completely characterize non-periodic balanced weighted shifts $S_{\lambdab}$ on rooted directed trees under a very mild assumption that $S_{\lambdab}^{*n}S_{\lambdab}^n|_{\ker S…

math.FA2021

Necessary conditions for existence of $Γ_{n}$ -contractions and examples of $Γ_{3}$ -contractions

Shubhankar Mandal, Avijit Pal

The fundamental result of B. Sz. Nazy states that every contraction has a coisometric extension and a unitary dilation. The isometric dilation of a contraction on a Hilbert space m…

Failure of Rational Dilation on the Tetrablock via Parrott Homomorphisms

Functional models for Γn​-contractions

Few maps in the rich structure for the domains GE(3;3;1,1,1)​ and GE(3;2;1,2)​

Function Theory and necessary conditions for a Schwarz lemma related to μ-Synthesis Domains

Unitary equivalence of balanced weighted shifts on rooted directed trees

Necessary conditions for existence of Γn​-contractions and examples of Γ3​-contractions

Functional models for $Γ_{n}$ -contractions

Few maps in the rich structure for the domains $G_{E (3; 3; 1, 1, 1)}$ and $G_{E (3; 2; 1, 2)}$

Function Theory and necessary conditions for a Schwarz lemma related to $μ$ -Synthesis Domains

Necessary conditions for existence of $Γ_{n}$ -contractions and examples of $Γ_{3}$ -contractions