Rigid circle domains with non-removable boundaries

Fuente: arXiv
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Autore principale: Rajala, Kai
Natura: Preprint
Pubblicazione: 2024
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author Rajala, Kai
author_facet Rajala, Kai
contents We give a negative answer to the rigidity conjecture of He and Schramm by constructing a rigid circle domain $Ω$ on the Riemann sphere with conformally non-removable boundary. Here rigidity means that every conformal map from $Ω$ onto another circle domain is a Möbius transformation, and non-removability means that there is a homeomorphism of the Riemann sphere which is conformal off $\partial Ω$ but not everywhere. Our construction is based on a theorem of Wu, which states that the product of any Cantor set $E$ with a sufficiently thick Cantor set $F$ is non-removable. We show that one can choose $E$ and $F$ so that the complement of the union of $E \times F$ and suitably placed disks is rigid. The proof of rigidity involves a metric characterization of conformal maps, which was recently proved by Ntalampekos. The other direction of the rigidity conjecture, i.e., whether removability of the boundary implies rigidity, remains open.
format Preprint
id arxiv_https___arxiv_org_abs_2409_19103
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Rigid circle domains with non-removable boundaries
Rajala, Kai
Complex Variables
30C20, 30C35
We give a negative answer to the rigidity conjecture of He and Schramm by constructing a rigid circle domain $Ω$ on the Riemann sphere with conformally non-removable boundary. Here rigidity means that every conformal map from $Ω$ onto another circle domain is a Möbius transformation, and non-removability means that there is a homeomorphism of the Riemann sphere which is conformal off $\partial Ω$ but not everywhere. Our construction is based on a theorem of Wu, which states that the product of any Cantor set $E$ with a sufficiently thick Cantor set $F$ is non-removable. We show that one can choose $E$ and $F$ so that the complement of the union of $E \times F$ and suitably placed disks is rigid. The proof of rigidity involves a metric characterization of conformal maps, which was recently proved by Ntalampekos. The other direction of the rigidity conjecture, i.e., whether removability of the boundary implies rigidity, remains open.
title Rigid circle domains with non-removable boundaries
topic Complex Variables
30C20, 30C35
url https://arxiv.org/abs/2409.19103