A General Coefficient Theorem for Univalent Functions: Generalization of the Bieberbach and Zalcman Conjectures

The main result of this paper is that any rotationally homogeneous polynomial functional J(f)=∑|α|=n0NCm1,…,msam1αm1…amsαms with |α|=αm1+⋯+αms≥3,2<am1<⋯<ams<∞, depending on the distinguished finitely many coefficients amj, is maximized on S by Koebe’s function κθ(z)=z/(1−eiθz)2 with θ∈[−π,π]. This includes, in particular, the well-known Bieberbach and Zalcman conjectures and covers many other coefficient estimates for univalent functions. As an application, the main theorem provides the solution of the generalized Zalcman conjecture posed by Ma.

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Publication Details

Journal
Axioms
Published
2026-03-17
DOI
https://doi.org/10.3390/axioms15030225
Primary Topic
Analytic and geometric function theory
Type
article
Field-Weighted Citation Impact
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article

A General Coefficient Theorem for Univalent Functions: Generalization of the Bieberbach and Zalcman Conjectures

Samuel L. Krushkal
Axioms
Analytic and geometric function theory
article

A General Coefficient Theorem for Univalent Functions: Generalization of the Bieberbach and Zalcman Conjectures

Samuel L. Krushkal
article en

Abstract

The main result of this paper is that any rotationally homogeneous polynomial functional J(f)=∑|α|=n0NCm1,…,msam1αm1…amsαms with |α|=αm1+⋯+αms≥3,2<am1<⋯<ams<∞, depending on the distinguished finitely many coefficients amj, is maximized on S by Koebe’s function κθ(z)=z/(1−eiθz)2 with θ∈[−π,π]. This includes, in particular, the well-known Bieberbach and Zalcman conjectures and covers many other coefficient estimates for univalent functions. As an application, the main theorem provides the solution of the generalized Zalcman conjecture posed by Ma.

AxiomsVol. 15(3)
Bar-Ilan University (IL), University of Virginia (US)
Openalex Percentile: Top 16%
Analytic and geometric function theory
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