The Sobolev extension problem on trees and in the plane

Let V be a finite tree with radially decaying weights. We show that there exists a set E⊂R2 $E\subset {\mathbb{R}}^{2}$ for which the following two problems are equivalent: (1) Given a (real-valued) function ϕ on the leaves of V, extend it to a function Φ on all of V so that ‖Φ‖L1,p(V) ${\Vert}{\Ph...

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Bibliographic Details
Main Authors: Carruth Jacob, Israel Arie
Format: Article
Language:English
Published: De Gruyter 2025-01-01
Series:Advanced Nonlinear Studies
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Online Access:https://doi.org/10.1515/ans-2023-0158
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Summary:Let V be a finite tree with radially decaying weights. We show that there exists a set E⊂R2 $E\subset {\mathbb{R}}^{2}$ for which the following two problems are equivalent: (1) Given a (real-valued) function ϕ on the leaves of V, extend it to a function Φ on all of V so that ‖Φ‖L1,p(V) ${\Vert}{\Phi}{{\Vert}}_{{L}^{1,p}\left(V\right)}$ has optimal order of magnitude. Here, L 1,p (V) is a weighted Sobolev space on V. (2) Given a function f:E→R $f:E\to \mathbb{R}$ , extend it to a function F∈L2,p(R2) $F\in {L}^{2,p}\left({\mathbb{R}}^{2}\right)$ so that ‖F‖L2,p(R2) ${\Vert}F{{\Vert}}_{{L}^{2,p}\left({\mathbb{R}}^{2}\right)}$ has optimal order of magnitude.
ISSN:2169-0375