This article is cited in
5 papers
Problems on extremal decomposition of the Riemann sphere. II
G. V. Kuz'mina St. Petersburg Department of V. A. Steklov Institute of Mathematics, Russian Academy of Sciences
Abstract:
In the present paper, we solve some problems on the maximum of the weighted sum
$$
\sum^n_{k=1}\alpha^2_kM(D_k, a_k)
$$
(
$M(D_k, a_k)$ denote the reduced module of the domian
$D_k$ with respect to the point
$a_k\in D_k$) in the family of all nonoverlapping simple connected domians
$D_k$,
$a_k\in D_k$,
$k=1,\dots,n$, where the points
$a_1,\dots,a_n$, are free parameters satisfying certain geometric conditions. The proofs involve a version of the method of extremal metric, which reveals a certain symmetry of the extremal system of the points
$a_1,\dots,a_n$. The problem on the maximum of the conformal invariant
\begin{equation}
2\pi\sum^5_{k=1}M(D_k,b_k)-\frac12\sum_{1\le b_k<b_l<5}\log|b_k-b_l|
\tag{*}
\end{equation}
for all systems of points
$b_1,\dots,b_s$ is also considered. In the case where the systems
$\{b_1,\dots,b_5\}$ are symmetric with respect to a certain circle, the problem was solved earlier. A theorem formulated in the author's previous work asserts that the maximum of invariant (*) for all system of points
$\{b_1,\dots,b_5\}$ is attained in a certain well-defined case. In the present work, it is shown that the proof of this theorem contains mistake. A possible proof of the theorem is outlined.
UDC:
517.54 Received: 25.12.2001
Revised: 25.03.2002