
arXiv: 2011.07261
Abstract We extend the classical Carathéodory extension theorem to quasiconformal Jordan domains ( Y , d Y ). We say that a metric space ( Y , d Y ) is a quasiconformal Jordan domain if the completion ̄ Y of ( Y , d Y ) has finite Hausdorff 2-measure, the boundary ∂ Y = ̄ Y \ Y is homeomorphic to 𝕊 1 , and there exists a homeomorphism ϕ : 𝔻 →( Y , d Y ) that is quasiconformal in the geometric sense. We show that ϕ has a continuous, monotone, and surjective extension Φ: 𝔻 ̄ → Y ̄. This result is best possible in this generality. In addition, we find a necessary and sufficient condition for Φ to be a quasiconformal homeomorphism. We provide sufficient conditions for the restriction of Φ to 𝕊 1 being a quasisymmetry and to ∂Y being bi-Lipschitz equivalent to a quasicircle in the plane.
primary 30l10, metric spaces, carathéodory, metric surface, funktioteoria, quasiconformal Jordan domains, Mathematics - Metric Geometry, Quasiconformal mappings in \(\mathbb{R}^n\), other generalizations, FOS: Mathematics, Matematiikka, Complex Variables (math.CV), Length, area, volume, other geometric measure theory, QA299.6-433, Carathéodory extension theorem, Mathematics - Complex Variables, ta111, Primary 30L10, Secondary 30C65, 28A75, 51F99, 52A38, beurling–ahlfors, Metric Geometry (math.MG), quasiconformal, secondary 30c65, 28a75, 51f99, Carathéodory, metriset avaruudet, Beurling–Ahlfors, Quasiconformal mappings in metric spaces, mittateoria, Mathematics, Analysis
primary 30l10, metric spaces, carathéodory, metric surface, funktioteoria, quasiconformal Jordan domains, Mathematics - Metric Geometry, Quasiconformal mappings in \(\mathbb{R}^n\), other generalizations, FOS: Mathematics, Matematiikka, Complex Variables (math.CV), Length, area, volume, other geometric measure theory, QA299.6-433, Carathéodory extension theorem, Mathematics - Complex Variables, ta111, Primary 30L10, Secondary 30C65, 28A75, 51F99, 52A38, beurling–ahlfors, Metric Geometry (math.MG), quasiconformal, secondary 30c65, 28a75, 51f99, Carathéodory, metriset avaruudet, Beurling–Ahlfors, Quasiconformal mappings in metric spaces, mittateoria, Mathematics, Analysis
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