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JOURNALS // Algebra i Analiz // Archive

Algebra i Analiz, 2016 Volume 28, Issue 6, Pages 189–207 (Mi aa1518)

This article is cited in 2 papers

Research Papers

Means of the power $-2$ of derivatives in the class $S$

N. A. Shirokovab

a St. Petersburg State University, Department of Mathematics and Mechanics, St. Petersburg, Russia
b National Research University "Higher School of Economics", St. Petersburg, Russia

Abstract: Let $S$ be the standard class of conformal mapping of the unit disk $\mathbb D$, and let $F\in \mathbb D$. Suppose that there exist Jordan domains $G_1$ and $G$, $G_1\supset G$, such that $G\subset \mathbb C\setminus f(\mathbb D)$, $\partial f(\mathbb D)\cap \partial G$ contains a Dini-smoth arc $\gamma$, and $G_1 \cap \partial f(\mathbb D) \cap \partial G=\gamma$. It is established that, in this case, for any $r$ with $0<r<1$, $F$ does not maximize the expression
$$\int _{|z|=r}\frac {1}{|F’(z)|^2} |dz| $$
in the class $S$.

Keywords: Brennan's conjecture, conformal mappings, means of the derivative of a conformal mapping, the class $S$.

Received: 07.06.2016


 English version:
St. Petersburg Mathematical Journal, 2017, 28:6, 855–867

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