English

Sets of absolute continuity for harmonic measure in NTA domains

Classical Analysis and ODEs 2016-03-09 v3 Analysis of PDEs Metric Geometry

Abstract

We show that if Ω\Omega is an NTA domain with harmonic measure ww and EΩE\subseteq \partial\Omega is contained in an Ahlfors regular set, then wEHdEw|_{E}\ll \mathscr{H}^{d}|_{E}. Moreover, this holds quantitatively in the sense that for all τ>0\tau>0 ww obeys an AA_{\infty}-type condition with respect to HdE\mathscr{H}^{d}|_{E'}, where EEE'\subseteq E is so that w(E\E)<τw(E)w(E\backslash E')<\tau w(E), even though Ω\partial\Omega may not even be locally Hd\mathscr{H}^{d}-finite. We also show that, for uniform domains with uniform complements, if EΩE\subseteq\partial\Omega is the Lipschitz image of a subset of Rd\mathbb{R}^{d}, then there is EEE'\subseteq E with Hd(E\E)<τHd(E)\mathscr{H}^{d}(E\backslash E')<\tau \mathscr{H}^{d}(E) upon which a similar AA_{\infty}-type condition holds.

Keywords

Cite

@article{arxiv.1410.2782,
  title  = {Sets of absolute continuity for harmonic measure in NTA domains},
  author = {Jonas Azzam},
  journal= {arXiv preprint arXiv:1410.2782},
  year   = {2016}
}

Comments

Made referee's recommended corrections, edited introduction, added a figure, removed a section in the appendix that is essentially known. To appear in Potential Analysis