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arXiv 2408.09759math.FAmath.CV
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Hardy空间的Beurling子空间之间的复合算子

Composition operators between Beurling subspaces of Hardy space

V. A. Anjali, P. Muthukumar, P. Shankar

AI总结:

本文在更一般框架下研究V. Matache提出的Hardy空间Beurling子空间复合算子不变性公开问题,刻画了满足不变性的全纯自映射与内函数,给出椭圆自同构情形的测度论刻画,并讨论了Blaschke乘积对应子空间不变的自映射求解问题。

摘要:

V. Matache(《J. Operator Theory》第73卷第1期:243-264页,2015年)提出了一个公开问题:刻画Hardy空间$H^2$上的复合算子$C_ϕ$,以及单位圆周上的非零奇异测度$μ_1$、$μ_2$,使得$C_ϕ({S_{μ_1}} H^2)\subseteq {S_{μ_2}} H^2$,其中$S_{μ_i}$表示对应于测度$μ_i$($i=1,2$)的奇异内函数。本文在更一般的框架下研究该问题,刻画了单位圆盘$\mathbb{D}$上的全纯自映射$ϕ$以及内函数$θ_1$、$θ_2$,使得对$p>0$有$C_ϕ(θ_1 H^p)\subseteq θ_2 H^p$,重点讨论了Blaschke乘积和奇异内函数这一特殊情形。当$ϕ$为椭圆自同构时,我们还给出了上述问题的另一种测度论刻画。对于给定的Blaschke乘积$θ$,我们讨论了寻找所有使得$θH^p$在$C_ϕ$下不变的自映射$ϕ$的问题。

英文摘要:

V. Matache (J. Operator Theory 73(1):243--264, 2015) raised an open problem about characterizing composition operators $C_ϕ$ on the Hardy space $H^2$ and nonzero singular measures $μ_1$, $μ_2$ on the unit circle such that $C_ϕ({S_{μ_1}} H^2)\subseteq {S_{μ_2}} H^2,$ where $S_{μ_i}$ denotes the singular inner function corresponding to the measure $μ_i,i=1,2$. In this article, we consider this problem in a more general setting. We characterize holomorphic self maps $ϕ$ of the unit disk $\mathbb{D}$ and inner functions $θ_1, θ_2$ such that $C_ϕ(θ_1 H^p)\subseteq θ_2 H^p,$ for $p>0$. Emphasis is given to Blaschke products and singular inner functions as a special case. We also give an another measure-theoretic characterization to above question when $ϕ$ is an elliptic automorphism. For a given Blaschke product $θ$, we discuss about finding all self maps $ϕ$ such that $θH^p$ is invariant under $C_ϕ$.

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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