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arXiv 2109.09012math.FA
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算子Berezin数的反向不等式

Reverse inequalities for the Berezin number of operators

Mubariz Garayev, Hocine Guediri, Najla Altwaijry

摘要:

对于再生核希尔伯特空间$\mathcal{H}(Ω)$上的有界线性算子$A$,在再生核为正规化的情况下,分别用$\widehat{k}_λ = \frac{k_λ}{\lVert k_λ\lVert}$,$ber(A) = \sup_{λ\inΩ}\left|\widetilde{A}(λ)\right|$和$\left\|A\right\|_{ber} = \sup_{λ\inΩ}\left\|A\widehat{k}_λ\right\|$定义Berezin符号,Berezin数和Berezin范数.这些特征之间的直接比较产生不等式$ber(A)\leq\left\|A\right\|_{ber}\leq\lVert A\lVert$。本文进一步证明了与之相关的不等式,并特别注意了相应的反向不等式。特别地,我们改进了上述不等式中的第一个,即我们证明了\ $ber(A)\leq\left( \left\|A\right\|_{ber}^{2}-\inf_{λ\inΩ}\left\lVert (A-\widetilde{A}(λ))\widehat{k}_λ\right\lVert^{2}\right) ^{\frac{1}{2}}$。

英文摘要:

For a bounded linear operator $A$ on a reproducing kernel Hilbert space $\mathcal{H}(Ω)$, with normalized reproducing kernel $\widehat{k}_λ = \frac{k_λ}{\lVert k_λ\lVert}$, the Berezin symbol, Berezin number and Berezin norm are defined respectively by $\widetilde{A}(λ) = \langle A\widehat{k}_λ,\widehat{k}_λ\rangle$, $ber(A) = \sup_{λ\inΩ}\left|\widetilde{A}(λ)\right|$ and $\left\|A\right\|_{ber} = \sup_{λ\inΩ}\left\|A\widehat{k}_λ\right\|$. A straightforward comparison between these characteristics yields the inequalities $ber(A)\leq\left\|A\right\|_{ber}\leq\lVert A\lVert$. In this paper, we prove further inequalities relating them, and give special care to the corresponding reverse inequalities. In particular, we refine the first one of the above inequalities, namely we prove that \ $ber(A)\leq\left( \left\|A\right\|_{ber}^{2}-\inf_{λ\inΩ}\left\lVert (A-\widetilde{A}(λ))\widehat{k}_λ\right\lVert^{2}\right) ^{\frac{1}{2}}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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