arXiv subjects
Publications and source records attributed to Włodzimierz Zwonek.
We show that pseudoconvex Reinhardt domains in dimension two with isomorphic semigroups of holomorphic endomorphisms are biholomorphically or anti-biholomorphically equivalent. Moreover, we show that every Stein manifold that retracts to a properly embedded copy of the punctured complex line, is determined (up to biholomorphic or anti-biholomorphic equivalence) by its semigroup of holomorphic endomorphisms.
In the paper we discuss the problem of existence, uniqueness and extension through the boundary of left inverses to complex geodesics in Lempert domains. We concentrate on special left inverses (so called Lempert left inverses) characterized by the fact that their fibers are intersections of affine hyperplanes with the domain.
Motivated by the way two special domains, namely the symmetrized bidisc and the tetrablock, could be defined as the images of $2$-proper holomorphic images of classical Cartan domains, we present a general approach to study $2$-proper holomorphic images of bounded symmetric domains. We show some special properties of $2$-proper holomorphic maps (such as the construction of some \textcolor{black}{involutive} automorphisms etc.) and enlist possible domains (up to biholomorphisms) which arise as $2$-proper holomorphic images of bounded symmetric domains. This leads us to a consideration of a new family of domains $\mathbb L_n$ for $n\geq 2.$ Let $L_n$ be an irreducible classical Cartan domain of type $IV$ (Lie ball) of dimension $n$ and $Λ_n : L_n \to Λ_n (L_n):=\mathbb L_n$ be the natural proper holomorphic mapping of multiplicity $2.$ It turns out that $\mathbb L_2$ and $\mathbb L_3$ are biholomorphic to the symmetrized bidisc and the tetrablock, respectively. In this article, we study function geometric properties of the family $\{\mathbb L_n : n \geq 2\}$ in a unified manner and thus extend results of many earlier papers on analogous properties of the symmetrized bidisc and the tetrablock. We show that $\mathbb L_n$ cannot be exhausted by domains biholomorhic to some convex domains. Any proper holomorphic self-mapping of $\mathbb L_n$ is an automorphism for $n \geq 3.$ Moreover, the automorphism group Aut$(\mathbb L_n)$ is isomorphic to Aut$( L_{n-1})$ and $\mathbb L_n$ is inhomogeneous for \textcolor{black}{$n\geq2$}. Additionally, we prove that $\mathbb L_n$ is not a Lu Qi-Keng domain for $n \geq 3.$omogeneous for $n\geq3$. Additionally, we prove that $\mathbb L_n$ is not a Lu Qi-Keng domain for $n \geq 3.$
Consider a holomorphic map $F: D \to G$ between two domains in ${\mathbb C}^N$. Let $\mathcal F$ denote a family of geodesics for the Kobayashi distance, such that $F$ acts as an isometry on each element of $\mathcal F$. This paper is dedicated to characterizing the scenarios in which the aforementioned condition implies that $F$ is a biholomorphism. Specifically, we establish this when $D$ is a complete hyperbolic domain, and $\mathcal F$ comprises all geodesic segments originating from a specific point. Another case is when $D$ and $G$ are $C^{2+α}$-smooth bounded pseudoconvex domains, and $\mathcal F$ consists of all geodesic rays converging at a designated boundary point of $D$. Furthermore, we provide examples to demonstrate that these assumptions are essentially optimal.
Motivated by recent papers \cite{For-Rong 2021} and \cite{Ng-Rong 2024} we prove a boundary Schwarz lemma (Burns-Krantz rigidity type theorem) for non-smooth boundary points of the polydisc and symmetrized bidisc. Basic tool in the proofs is the phenomenon of invariance of complex geodesics (and their left inverses) being somehow regular at the boundary point under the mapping satisfying the property as in the Burns-Krantz rigidity theorem that lets the problem reduce to one dimensional problem. Additionally, we make a discussion on bounded symmetric domains and suggest a way to prove the Burns-Krantz rigidity type theorem in these domains that however cannot be applied for all bounded symmetric domains.
In this article, we study various properties of holomorphic retracts in Lempert domains. We associate the existence and the related form of holomorphic retracts with the linear ones, provide non-trivial examples and discuss their properties in a quite general setting. Later we specialize on two Lempert domains which are the Lie ball of dimension three and its $2$-proper holomorphic image, that is, the tetrablock and give a complete description of holomorphic retracts in these domains.
We show the (anti)holomorphicity of smooth Kobayashi isometries of the diamond, the domain defined as $\triangle:=\{z\in\mathbb C^2:|z_1|+|z_2|<1\}$. Additionally, we discuss the problem of uniqueness of real geodesics, left inverses and strict convexity of indicatrices.
In this paper we study the following "slice rigidity property": given two Kobayashi complete hyperbolic manifolds $M, N$ and a collection of complex geodesics $\mathcal F$ of $M$, when is it true that every holomorphic map $F:M\to N$ which maps isometrically every complex geodesic of $\mathcal F$ onto a complex geodesic of $N$ is a biholomorphism? Among other things, we prove that this is the case if $M, N$ are smooth bounded strictly (linearly) convex domains, every element of $\mathcal F$ contains a given point of $\overline{M}$ and $\mathcal F$ spans all of $M$. More general results are provided in dimension $2$ and for the unit ball.
In the paper we study properties of symmetric powers of complex manifolds. We investigate a number of function theoretic properties (e. g. (quasi) $c$-finite compactness, existence of peak functions) that are preserved by taking the symmetric power. The case of symmetric products of planar domains is studied in a more detailed way. In particular, a complete description of the Carathéodory and Kobayashi hyperbolicity and Kobayashi completeness in that class of domains is presented.
Carleson showed that the Bergman space for a domain on the plane is trivial if and only if its complement is polar. Here we give a quantitative version of this result. One is the Suita conjecture, established by the first-named author in 2012, the other is an upper bound for the Bergman kernel in terms of logarithmic capacity. We give some other estimates for those quantities as well. We also show that the volume of sublevel sets for the Green function is not convex for all regular non simply connected domains, generalizing a recent example of Fornæss.
We solve a three point Nevanlinna-Pick problem in the Euclidean ball. In particular, we determine a class of rational functions that interpolate this problem.
We give an improved lower bound for the error of any quadrature computing $\int_{-1}^1 f(x) dα(x)$ of analytic functions bounded in the neighborhood of $[-1,1]$.
In the paper we discuss three different notions of extremal holomorphic mappings: weak $m$-extremals, $m$-extremals and $m$-complex geodesics. We discuss relations between them in general case and in the special cases of unit ball, classical Cartan domains, symmetrised bidisc and tetrablock. In particular we show that weak $3$-extremal maps in the symmetrised bidisc are rational thus giving the (partial) answer to a problem posed in a recent paper by J. Agler, Z. Lykova and N. J. Young.
In the paper we study the geometry of semitube domains in $\mathbb C^2$. In particular, we extend the result of Burgués and Dwilewicz for semitube domains dropping out the smoothness assumption. We also prove various properties of non-smooth pseudoconvex semitube domains obtaining among others a relation between pseudoconvexity of a semitube domain and the number of connected components of its vertical slices. Finally, we present an example showing that there is a non-convex domain in $\mathbb C^n$ such that its image under arbitrary isometry is pseudoconvex.
It has been recently shown that for a convex domain $Ω$ in $\mathbb C^n$ and $w\inΩ$ the function $F_Ω(w):=\big(K_Ω(w)λ(I_Ω(w))\big)^{1/n}$, where $K_Ω$ is the Bergman kernel on the diagonal and $I_Ω(w)$ the Kobayashi indicatrix, satisfies $1\leq F_Ω\leq 4$. While the lower bound is optimal, not much more is known about the upper bound. In general it is quite difficult to compute $F_Ω$ even numerically and the highest value of it obtained so far is $1.010182\dots$ In this paper we present precise, although rather complicated formulas for the ellipsoids $Ω=\{|z_1|^{2m}+|z_2|^2<1\}$ (with $m\geq 1/2$) and all $w$, as well as for $Ω=\{|z_1|+|z_2|<1\}$ and $w$ on the diagonal. The Bergman kernel for those ellipsoids had been known, the main point is to compute the volume of the Kobayashi indicatrix. It turns out that in the second case the function $λ(I_Ω(w))$ is not $C^{3,1}$.
We study the lower bound for the Bergman kernel in terms of volume of sublevel sets of the pluricomplex Green function. We show that it implies a bound in terms of volume of the Azukawa indicatrix which can be treated as a multidimensional version of the Suita conjecture. We also prove that the corresponding upper bound holds for convex domains and discuss it in bigger detail on some convex complex ellipsoids.
In this short note we show that the tetrablock is i $\C$-convex domain. In the proof of this fact a new class of ($\C$-convex) domains is studied. The domains are natural caniddates to study on them the behavior of holomorphically invariant functions.
In the paper we show that the Lempert theorem (i.e. the equality between the Lempert function and the Carathéodory distance) holds in the tetrablock, a bounded hyperconvex domain which is not biholomorphic to a convex domain.