| Autor: |
Bhunia, P., Garayev, M. T., Paul, K., Tapdigoglu, R. |
| Zdroj: |
Complex Analysis & Operator Theory; Sep2023, Vol. 17 Issue 6, p1-15, 15p |
| Abstrakt: |
We study some problems of operator theory by using Berezin symbols approach. Namely, we investigate in terms of Berezin symbols invariant subspaces of isometric composition operators on H Ω. We discuss operator corona problem, in particular, the Toeplitz corona problem. Further, we characterize unitary operators in terms of Berezin symbols. We show that the well known inequality w A ≥ 1 2 A for numerical radius is not true for the Berezin number of operators, which is defined by ber A : = sup λ ∈ Ω A ~ λ , where A ~ λ : = A k ^ λ , k ^ λ is the Berezin symbol of operator A : H Ω → H Ω. Finally, we provide a lower bound for ber A. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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