Computational Methods and Function Theory ( IF 0.6 ) Pub Date : 2021-04-10 , DOI: 10.1007/s40315-021-00372-x Stephen Deterding
Let X be a compact subset of the complex plane with the property that every relatively open subset of X has positive area and let \(A_0(X)\) denote the space of VMO functions that are analytic on X. \(A_0(X)\) is said to admit a bounded point derivation of order t at a point \(x_0 \in \partial X\) if there exists a constant C such that \(|f^{(t)}(x_0)|\le C \Vert f\Vert _{{\text {BMO}}}\) for all functions in \({\text {VMO}}(X)\) that are analytic on X. In this paper, we give necessary and sufficient conditions in terms of lower 1-dimensional Hausdorff content for \(A_0(X)\) to admit a bounded point derivation at \(x_0\). These conditions are similar to conditions for the existence of bounded point derivations on other functions spaces.
中文翻译:
界点导数和界均值振荡函数
令X为复平面的紧子集,其性质为X的每个相对开放子集均具有正面积,令\(A_0(X)\)表示对X进行分析的VMO函数的空间。\(A_0(X)\)被认为承认的顺序的有界点推导吨在点\(X_0 \在\局部X \)如果存在一个常数C ^使得\(| F ^ {(T)} (X_0)| \文件ç\ Vert的˚F\ Vert的_ {{\文本{BMO}}} \)用于所有功能\({\文本{VMO}}(X)\)是上解析X。在本文中,我们针对\(A_0(X)\)的较低一维Hausdorff含量给出了充要条件,以允许在\(x_0 \)处有界点导数。这些条件类似于其他函数空间上存在有界点推导的条件。