English

An extremal decomposition problem for harmonic measure

Complex Variables 2011-03-03 v4

Abstract

Let EE be a continuum in the closed unit disk z1|z|\le 1 of the complex zz-plane which divides the open disk z<1|z| < 1 into n2n\ge 2 pairwise non-intersecting simply connected domains Dk,D_k, such that each of the domains DkD_k contains some point aka_k on a prescribed circle z=ρ,0<ρ<1,k=1,...,n.|z| = \rho, 0 <\rho <1, k=1,...,n\,. It is shown that for some increasing function Ψ\Psi\, independent of EE and the choice of the points ak,a_k, the mean value of the harmonic measures Ψ1\[1nk=1kΨ(ω(ak,E,Dk))] \Psi^{-1}\[ \frac{1}{n} \sum_{k=1}^{k} \Psi(\omega(a_k,E, D_k))] is greater than or equal to the harmonic measure ω(ρ,E,D),\omega(\rho, E^*, D^*)\,, where E={z:zn[1,0]}E^* = \{z: z^n \in [-1,0] \} and D={z:z<1,argz<π/n}.D^* =\{z: |z|<1, |{\rm arg} z| < \pi/n\} \,. This implies, for instance, a solution to a problem of R.W. Barnard, L. Cole, and A. Yu. Solynin concerning a lower estimate of the quantity infEmaxk=1,...,nω(ak,E,Dk)\inf_{E} \max_{k=1,...,n} \omega(a_k,E, D_k)\, for arbitrary points of the circle z=ρ.|z| = \rho \,. These authors stated this hypothesis in the particular case when the points are equally distributed on the circle z=ρ.|z| = \rho \,.

Keywords

Cite

@article{arxiv.1011.4178,
  title  = {An extremal decomposition problem for harmonic measure},
  author = {V. N. Dubinin and M. Vuorinen},
  journal= {arXiv preprint arXiv:1011.4178},
  year   = {2011}
}

Comments

6 pages, 2 figures

R2 v1 2026-06-21T16:45:38.677Z