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Publication Detailed Description
Journal Title
Forum Mathematicum
Year (definitive publication)
2024
Language
English
Country
Germany
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Abstract
In this note, we characterize the essential numerical range of a block diagonal operator T = ?i Ti in terms of the numerical ranges {W(Ti)}i of its components. Specifically, the essential numerical range of T is the convex hull of the limit superior of {W(Ti)}i. This characterization can be simplified further. In fact, we prove the existence of a decomposition of T for which the convex hull is not required.
Acknowledgements
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Keywords
Block diagonal operator,Essential numerical range
Fields of Science and Technology Classification
- Mathematics - Natural Sciences
Funding Records
| Funding Reference | Funding Entity |
|---|---|
| UID/MAT/04459/2019 | Fundação para a Ciência e a Tecnologia |
| UIDB/00212/2020 | Fundação para a Ciência e a Tecnologia |
| UIDB/04674/2020 | Fundação para a Ciência e a Tecnologia |
