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JOURNALS // Doklady Rossijskoj Akademii Nauk. Mathematika, Informatika, Processy Upravlenia // Archive

Dokl. RAN. Math. Inf. Proc. Upr., 2025 Volume 522, Pages 25–32 (Mi danma631)

MATHEMATICS

Generalization of the Julia–Carathéodory theorem to the case of several boundary fixed points

O. S. Kudryavtsevaab

a Moscow Center for Fundamental and Applied Mathematics
b Volgograd State Technical University

Abstract: Holomorphic self-maps of the unit disc with boundary fixed points are investigated. In 1982, Cowen and Pommerenke established an interesting generalization of the classical Julia–Carathéodory theorem, which allowed them to derive an exact estimate for the derivative at the Denjoy–Wolff point on a class of functions with an arbitrary finite set of boundary fixed points. In this paper, we obtain a new generalization of the Julia–Carathéodory theorem, which contains Cowen–Pommerenke result as a special case, moreover, it is an effective tool for solving various problems on classes of functions with fixed points.

Keywords: holomorphic map, fixed points, angular derivative, Julia–Carathéodory theorem.

UDC: 517.54

Presented: B. S. Kashin
Received: 14.02.2025
Revised: 29.03.2025
Accepted: 01.04.2025

DOI: 10.31857/S2686954325020059


 English version:
Doklady Mathematics, 2025, 111:2, 114–120

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© Steklov Math. Inst. of RAS, 2026