English

Planar $W^{1,\,1}$-extension domains

Functional Analysis 2025-12-11 v1 Complex Variables

Abstract

We show that a bounded planar simply connected domain Ω\Omega is a W1,1W^{1,\,1}-extension domain if and only if for every pair x,yx,y of points in Ωc\Omega^c there exists a curve γΩc\gamma \subset \Omega^c connecting xx and yy with γ1χR2Ω(z)ds(z)Cxy. \int_\gamma \frac{1}{\chi_{\mathbb R^2\setminus \partial\Omega}(z)}\,ds(z) \le C|x-y|. Consequently, a planar Jordan domain Ω\Omega is a W1,1W^{1,\,1}-extension domain if and only if it is a BVBV-extension domain, and if and only if its complementary domain Ω~\tilde \Omega is a W1,W^{1,\,\infty}-extension domain.

Cite

@article{arxiv.2512.09167,
  title  = {Planar $W^{1,\,1}$-extension domains},
  author = {Pekka Koskela and Tapio Rajala and Yi Ru-Ya Zhang},
  journal= {arXiv preprint arXiv:2512.09167},
  year   = {2025}
}

Comments

53 pages, 5 figures

R2 v1 2026-07-01T08:18:04.907Z