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JOURNALS // Izvestiya Vysshikh Uchebnykh Zavedenii. Matematika // Archive

Izv. Vyssh. Uchebn. Zaved. Mat., 2009 Number 12, Pages 84–89 (Mi ivm6029)

This article is cited in 3 papers

Brief communications

Generalization of theorems of Szász and Ruscheweyh on exact bounds for derivatives of analytic functions

D. Kh. Giniyatova

Chair of Functions Theory and Approximations, Kazan State University, Kazan, Russia

Abstract: Let $\Omega$ and $\Pi$ be two domains in the extended complex plane equipped by the Poincaré metric. In this paper we obtain analogs of Schwarz–Pick type inequalities in the class $A(\Omega,\Pi)=\{f\colon\Omega\to\Pi\}$ of functions locally holomorphic in $\Omega$; for the domain $\Omega$ we consider the exterior of the unit disk and the upper half-plane. The obtained results generalize the well-known theorems of Szasz and Ruscheweyh about the exact estimates of derivatives of analytic functions defined on the disk $|z|<1$.

Keywords: Schwarz–Pick type inequalities, analytic functions, Poincaré metric.

UDC: 517.544

Received: 22.05.2009


 English version:
Russian Mathematics (Izvestiya VUZ. Matematika), 2009, 53:12, 72–76

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