On the Harmonic characterization of domains via mean value formulas

  • Giovanni Cupini University of Bologna, Italy
  • Ermanno Lanconelli University of Bologna, Italy

Abstract

The Euclidean ball have the following harmonic characterization, via Gauss-mean value property: Let D be an open set with finite Lebesgue measure and let x0 be a point of D. If 

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for every nonnegative harmonic function u in D, then D is a Euclidean ball centered at x0. On the other hand, on every sufficiently smooth domain D and for every point x0 in there exist Radon measures μ such that
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for every nonnegative harmonic function u in D. In this paper we give sufficient conditions so that this last mean value property characterizes the domain D.

Published
2019-12-24
Section
Articoli