Numerical Ranges and Spectral Sets: the unbounded case
Fuente:
arXiv
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| Autor principal: | |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866914053819990016 |
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| author | Crouzeix, Michel |
| author_facet | Crouzeix, Michel |
| contents | It is known that, if $Ω$ $\subset$ C is a convex set containing the numerical range of an operator A, then $Ω$ is a C $Ω$ -spectral set for A with C $Ω$ $\le$ 1+ $\sqrt$ 2. We improve this estimate in unbounded cases. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_19792 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Numerical Ranges and Spectral Sets: the unbounded case Crouzeix, Michel Functional Analysis Numerical Analysis It is known that, if $Ω$ $\subset$ C is a convex set containing the numerical range of an operator A, then $Ω$ is a C $Ω$ -spectral set for A with C $Ω$ $\le$ 1+ $\sqrt$ 2. We improve this estimate in unbounded cases. |
| title | Numerical Ranges and Spectral Sets: the unbounded case |
| topic | Functional Analysis Numerical Analysis |
| url | https://arxiv.org/abs/2509.19792 |