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Open AccessArticle
Initial Coefficient Behavior of Bi-Univalent Functions Defined Through Bernoulli Polynomial Subordination
by
Mohamed Illafe
Mohamed Illafe 1,2,*
,
Abdulmtalb Hussen
Abdulmtalb Hussen 1,3
and
Feras Yousef
Feras Yousef 4,5
1
School of Engineering, Math & Technology, Navajo Technical University, Crownpoint, NM 87313, USA
2
Department of Mathematics, University of Benghazi, Benghazi 16063, Libya
3
Mathematics Department, College of Education, Al Zintan University, Dirj 00218, Libya
4
Department of Mathematics, The University of Jordan, Amman 11942, Jordan
5
Department of Mathematics, Hampton University, Hampton, VA 23669, USA
*
Author to whom correspondence should be addressed.
Mathematics 2026, 14(10), 1712; https://doi.org/10.3390/math14101712 (registering DOI)
Submission received: 24 March 2026
/
Revised: 5 May 2026
/
Accepted: 14 May 2026
/
Published: 16 May 2026
Abstract
The study of coefficient problems for bi-univalent functions continues to play a central role in geometric function theory due to its analytical depth and wide range of applications. In this paper, we introduce a new subclass of bi-univalent functions defined through subordination to the generating function of Bernoulli polynomials. We derive explicit upper bounds for the initial Taylor–Maclaurin coefficients and establish a corresponding Fekete–Szegö-type inequality for functions in this class. The results obtained provide refined estimates that extend several known findings in the literature and reveal the effectiveness of Bernoulli polynomial subordination as a unifying framework for investigating coefficient problems in the theory of bi-univalent functions. Various special cases are also discussed to demonstrate the scope and applicability of the main results.
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MDPI and ACS Style
Illafe, M.; Hussen, A.; Yousef, F.
Initial Coefficient Behavior of Bi-Univalent Functions Defined Through Bernoulli Polynomial Subordination. Mathematics 2026, 14, 1712.
https://doi.org/10.3390/math14101712
AMA Style
Illafe M, Hussen A, Yousef F.
Initial Coefficient Behavior of Bi-Univalent Functions Defined Through Bernoulli Polynomial Subordination. Mathematics. 2026; 14(10):1712.
https://doi.org/10.3390/math14101712
Chicago/Turabian Style
Illafe, Mohamed, Abdulmtalb Hussen, and Feras Yousef.
2026. "Initial Coefficient Behavior of Bi-Univalent Functions Defined Through Bernoulli Polynomial Subordination" Mathematics 14, no. 10: 1712.
https://doi.org/10.3390/math14101712
APA Style
Illafe, M., Hussen, A., & Yousef, F.
(2026). Initial Coefficient Behavior of Bi-Univalent Functions Defined Through Bernoulli Polynomial Subordination. Mathematics, 14(10), 1712.
https://doi.org/10.3390/math14101712
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