Completely non-unitary contractions and analyticity

We study completely non-unitary contractions T with finite dimensional defect spaces DT and DT∗. We present a complete classification of all such contractions T that satisfy a generalized property of the Hardy shift operator: DT⊆DT∗. We show that T is analytic if and only if it has no non-zero eigenvalue. Furthermore, we characterize the hyponormality of all those T.

Authors

Publication Details

Journal
Journal of Operator Theory
Published
2025-09-28
DOI
https://doi.org/10.7900/jot.2023aug23.2444
Primary Topic
Control and Stability of Dynamical Systems
Type
article
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article

Completely non-unitary contractions and analyticity

Susmita Das
Journal of Operator Theory
Control and Stability of Dynamical Systems
article

Completely non-unitary contractions and analyticity

Susmita Das
article en

Abstract

We study completely non-unitary contractions T with finite dimensional defect spaces DT and DT∗. We present a complete classification of all such contractions T that satisfy a generalized property of the Hardy shift operator: DT⊆DT∗. We show that T is analytic if and only if it has no non-zero eigenvalue. Furthermore, we characterize the hyponormality of all those T.

Journal of Operator TheoryVol. 94(1)
Openalex Percentile: Top 67%
Control and Stability of Dynamical Systems
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Completely non-unitary contractions and analyticity — Susmita Das · Journal of Operator Theory (2025) | TGRS Research Map | TGRS