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arXiv 1807.08002math.APmath.CA
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具有Hölder数据的调和测度两相问题奇异集的正则性

Regularity of the singular set in a two-phase problem for harmonic measure with Hölder data

Matthew Badger, Max Engelstein, Tatiana Toro

摘要:

在调和测度的非变分两相自由边界问题中,我们研究了区域$Ω\subset \mathbb{R}^n$的内外调和测度之间的关系如何影响其边界的几何形状.这种类型的自由边界问题最初是由凯尼格和托罗在2006年研究,并进一步研究了一系列单独和联合调查的几个作者。本文的重点是奇异集的自由边界,其中的边界看起来无穷小像零集齐次调和多项式的次数至少为2。证明了如果外调和测度关于内调和测度的Radon-Nikodym导数具有Hölder连续对数,则自由边界在每个奇点处存在唯一的几何爆破,且奇异集可以被可数个维数至多为$n-3$的$C^{1,β}$子流形覆盖.这一结果部分是通过调整工具,如Garofalo和Petrosyan的Weiss型单调性公式和上围不等式的调和函数从变分到非变分设置。

英文摘要:

In non-variational two-phase free boundary problems for harmonic measure, we examine how the relationship between the interior and exterior harmonic measures of a domain $Ω\subset \mathbb{R}^n$ influences the geometry of its boundary. This type of free boundary problem was initially studied by Kenig and Toro in 2006 and was further examined in a series of separate and joint investigations by several authors. The focus of the present paper is on the singular set in the free boundary, where the boundary looks infinitesimally like zero sets of homogeneous harmonic polynomials of degree at least 2. We prove that if the Radon-Nikodym derivative of the exterior harmonic measure with respect to the interior harmonic measure has a Hölder continuous logarithm, then the free boundary admits unique geometric blowups at every singular point and the singular set can be covered by countably many $C^{1,β}$ submanifolds of dimension at most $n-3$. This result is partly obtained by adapting tools such as Garofalo and Petrosyan's Weiss type monotonicity formula and an epiperimetric inequality for harmonic functions from the variational to the non-variational setting.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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