Abstract
We apply the capacity and symmetrization methods to distortion theorems for analytic functions in an annulus. We show that the classical Teichmüller estimate for the capacity of a doubly-connected domain yields a series of the already known and new inequalities for univalent functions. In particular, we supplement the results of Grötzsch, Duren, and Huckemann. Using the dissymmetrization of condensers we establish sharp estimates for local distortion and the distortion of level curves in n ≥ 2 symmetric directions. In terms of Robin functions we give an analog of the Nehari inequality: some general distortion theorem for several points taking into account the boundary behavior of the function and describing the cases of equalities. As a corollary we give analogs of some inequalities of Solynin, Pommerenke, and Vasil’ev that were obtained previously for univalent and bounded functions in a disk. We prove a distortion theorem that involves the Schwarzian derivatives at symmetric points on the unit circle.
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Original Russian Text Copyright © 2010 Dubinin V. N. and Prilepkina E. G.
The authors were supported by the Russian Foundation for Basic Research (Grant 08-01-00028), the State Maintenance Program for the Leading Scientific Schools of the Russian Federation (Grant NSh-2810.2008.1), and the Far East Division of the Russian Academy of Sciences (Grant 09-II-CO-01-003).
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Translated from Sibirskiĭ Matematicheskiĭ Zhurnal, Vol. 51, No. 2, pp. 285–302, March–April, 2010.
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Dubinin, V.N., Prilepkina, E.G. Distortion theorems for univalent meromorphic functions on an annulus. Sib Math J 51, 229–243 (2010). https://doi.org/10.1007/s11202-010-0023-6
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DOI: https://doi.org/10.1007/s11202-010-0023-6