Negative Powers of Contractions Having a Strong AA+ Spectrum
Zarrabi proved in 1993 that if the spectrum of a contraction T on a Banach space is a countable subset of the unit circle 𝕋, and if limn→+∞log(‖T−n‖)n=0{\lim _{n \to + \infty }}{{\log \left( {\left\| {{T^{ - n}}} \right\|} \right)} \over {\sqrt n }} = 0, then T is an isometry, so that ‖Tn‖ = 1 for...
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| Format: | Article |
| Language: | English |
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Sciendo
2023-05-01
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| Series: | Moroccan Journal of Pure and Applied Analysis |
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| Online Access: | https://doi.org/10.2478/mjpaa-2023-0015 |