Operators on Hilbert Space having $\Gamma_{E(3; 3; 1, 1, 1)}$ and $\Gamma_{E(3; 2; 1, 2)}$ as Spectral Sets
Functional Analysis
2025-10-30 v1
Abstract
A 7-tuple of commuting bounded operators T=(T1,…,T7) on a Hilbert space H is called a \textit{ΓE(3;3;1,1,1)-contraction} if ΓE(3;3;1,1,1) is a spectral set for T. Let (S1,S2,S3) and (S~1,S~2) be tuples of commuting bounded operators defined on a Hilbert space H with SiS~j=S~jSi for 1⩽i⩽3 and 1⩽j⩽2. We say that S=(S1,S2,S3,S~1,S~2) is a ΓE(3;2;1,2)-contraction if ΓE(3;2;1,2) is a spectral set for S. We derive various properties of ΓE(3;3;1,1,1)-contractions and ΓE(3;2;1,2)-contractions and establish a relationship between them. We discuss the fundamental equations for ΓE(3;3;1,1,1)-contractions and ΓE(3;2;1,2)-contractions. We explore the structure of ΓE(3;3;1,1,1)-unitaries and ΓE(3;2;1,2)-unitaries and elaborate on the relationship between them. We also study various properties of ΓE(3;3;1,1,1)-isometries and ΓE(3;2;1,2)-isometries. We discuss the Wold Decomposition for a ΓE(3;3;1,1,1)-isometry and a ΓE(3;2;1,2)-isometry. We further outline the structure theorem for a pure ΓE(3;3;1,1,1)-isometry and a pure ΓE(3;2;1,2)-isometry.
Cite
@article{arxiv.2510.25666,
title = {Operators on Hilbert Space having $\Gamma_{E(3; 3; 1, 1, 1)}$ and $\Gamma_{E(3; 2; 1, 2)}$ as Spectral Sets},
author = {Dinesh Kumar Keshari and Avijit Pal and Bhaskar Paul},
journal= {arXiv preprint arXiv:2510.25666},
year = {2025}
}