On certain subclasses of bounded univalent functions

J. Fuka; Z. J. Jakubowski

Annales Polonici Mathematici (1991)

  • Volume: 55, Issue: 1, page 109-115
  • ISSN: 0066-2216

Abstract

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Let = z ∈ ℂ; |z| < 1, T = z ∈ ℂ; |z|=1. Denote by S the class of functions f of the form f(z) = z + a₂z² + ... holomorphic and univalent in , and by S(M), M > 1, the subclass of functions f of the family S such that |f(z)| < M in . We introduce (and investigate the basic properties of) the class S(M,m;α), 0 < m ≤ M < ∞, 0 ≤ α ≤ 1, of bounded functions f of the family S for which there exists an open a r c I α = I α ( f ) T of length 2πα such that l i m ¯ z z , z | f ( z ) | M for every z I α and l i m ¯ z z , z | f ( z ) | m for every z T Ī α .

How to cite

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J. Fuka, and Z. J. Jakubowski. "On certain subclasses of bounded univalent functions." Annales Polonici Mathematici 55.1 (1991): 109-115. <http://eudml.org/doc/262312>.

@article{J1991,
abstract = {Let = z ∈ ℂ; |z| < 1, T = z ∈ ℂ; |z|=1. Denote by S the class of functions f of the form f(z) = z + a₂z² + ... holomorphic and univalent in , and by S(M), M > 1, the subclass of functions f of the family S such that |f(z)| < M in . We introduce (and investigate the basic properties of) the class S(M,m;α), 0 < m ≤ M < ∞, 0 ≤ α ≤ 1, of bounded functions f of the family S for which there exists an open $arc I_α = I_α(f) ⊂ T$ of length 2πα such that $\overline\{lim\}_\{z→ z₀, z ∈ \} |f(z)| ≤ M$ for every $z₀ ∈ I_α$ and $\overline\{lim\}_\{z→ z₀,z∈ \} |f(z)|≤ m$ for every $z₀ ∈ T \ Ī_α$.},
author = {J. Fuka, Z. J. Jakubowski},
journal = {Annales Polonici Mathematici},
keywords = {two constant theorem; harmonic measure; univalent; bounded functions; Pick's function; Koebe function; compactness; topology of uniform convergence},
language = {eng},
number = {1},
pages = {109-115},
title = {On certain subclasses of bounded univalent functions},
url = {http://eudml.org/doc/262312},
volume = {55},
year = {1991},
}

TY - JOUR
AU - J. Fuka
AU - Z. J. Jakubowski
TI - On certain subclasses of bounded univalent functions
JO - Annales Polonici Mathematici
PY - 1991
VL - 55
IS - 1
SP - 109
EP - 115
AB - Let = z ∈ ℂ; |z| < 1, T = z ∈ ℂ; |z|=1. Denote by S the class of functions f of the form f(z) = z + a₂z² + ... holomorphic and univalent in , and by S(M), M > 1, the subclass of functions f of the family S such that |f(z)| < M in . We introduce (and investigate the basic properties of) the class S(M,m;α), 0 < m ≤ M < ∞, 0 ≤ α ≤ 1, of bounded functions f of the family S for which there exists an open $arc I_α = I_α(f) ⊂ T$ of length 2πα such that $\overline{lim}_{z→ z₀, z ∈ } |f(z)| ≤ M$ for every $z₀ ∈ I_α$ and $\overline{lim}_{z→ z₀,z∈ } |f(z)|≤ m$ for every $z₀ ∈ T \ Ī_α$.
LA - eng
KW - two constant theorem; harmonic measure; univalent; bounded functions; Pick's function; Koebe function; compactness; topology of uniform convergence
UR - http://eudml.org/doc/262312
ER -

References

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  1. [1] J. Fuka and Z. Jakubowski, On certain subclasses of bounded univalent functions, in: Proc. of the XI-th Instructional Conference on the Theory of Extremal Problems, Łódź, 1990, 20-27 (in Polish). Zbl0755.30023
  2. [2] A. I. Markushevich, Theory of Analytic Functions, Vol. 2, Nauka, Moscow 1968 (in Russian). Zbl0506.01013
  3. [3] P. T. Mocanu, Une propriété de convexité généralisée dans la théorie de la représentation conforme, Mathematica (Cluj) 11 (1969), 127-133. Zbl0195.36401
  4. [4] G. Pick, Über die konforme Abbildung eines Kreises auf ein schlichtes und zugleich beschränktes Gebiet, Sitzungsber. Akad. Wiss. Wien 126 (1917), 247-263. Zbl46.0553.01
  5. [5] K. Skalska, Certain subclasses of the class of typically real functions, Ann. Polon. Math. 38 (1980), 141-152. Zbl0465.30012

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