Non-extendability of holomorphic functions with bounded or continuously extendable derivatives

Abstract

We consider the spaces $H_{F}^{\infty}(Ω)$ and $\mathcal{A}_{F}(Ω)$ containing all holomorphic functions $f$ on an open set $Ω\subseteq \mathbb{C}$, such that all derivatives $f^{(l)}$, $l\in F \subseteq \mathbb{N}_0=\{ 0,1,...\}$, are bounded on $Ω$, or continuously extendable on $\overlineΩ$, respectively. We endow these spaces with their natural topologies and they become Fréchet spaces. We prove that the set $S$ of non-extendable functions in each of these spaces is either void, or dense and $G_δ$. We give examples where $S=\varnothing$ or not. Furthermore, we examine cases where $F$ can be replaced by $\widetilde{F}=\{ l\in \mathbb{N}_0:\min F \leqslant l \leqslant \sup F\}$, or $\widetilde{F}_0= \{ l\in \mathbb{N}_0:0\leqslant l \leqslant \sup F\}$ and the corresponding spaces stay unchanged.