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http://hdl.handle.net/10071/30724| Author(s): | Carvalho, L. Diogo, C. Mendes, S. Soares, H. |
| Date: | 2024 |
| Title: | A note on the essential numerical range of block diagonal operators |
| Journal title: | Forum Mathematicum |
| Volume: | 36 |
| Number: | 5 |
| Pages: | 1147 - 1157 |
| Reference: | Carvalho, L., Diogo, C., Mendes, S., & Soares, H. (2024). A note on the essential numerical range of block diagonal operators. Forum Mathematicum, 36(5), 1147-1157. https://doi.org/10.1515/forum-2023-0166 |
| ISSN: | 0933-7741 |
| DOI (Digital Object Identifier): | 10.1515/forum-2023-0166 |
| Keywords: | Block diagonal operator Essential numerical range |
| 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. |
| Peerreviewed: | yes |
| Access type: | Open Access |
| Appears in Collections: | BRU-RI - Artigos em revistas científicas internacionais com arbitragem científica |
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| File | Size | Format | |
|---|---|---|---|
| article_98792.pdf | 251,69 kB | Adobe PDF | View/Open |
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