On coefficient problems for bounded turning functions associated with a strip domain

Dong Guo; Zongtao Li; Xi Luo; Dong Guo; Zongtao Li; Xi Luo

doi:10.3934/math.20261358

AIMS Mathematics

2026, Volume 11, Issue 10: 34884-34906. doi: 10.3934/math.20261358

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Research article

On coefficient problems for bounded turning functions associated with a strip domain

Dong Guo ^{1
,
,},
Zongtao Li ²,
Xi Luo ^{3
,
,}

1.
School of Mathematical Sciences, Yangzhou Polytechnic University, Yangzhou 225009, China
2.
School of Public Basic Education, Guangzhou Civil Aviation College, Guangzhou 510403, China
3.
School of Mathematics, Jiaying University, Jiaying 514015, China

Received: 28 July 2026 Revised: 13 October 2026 Accepted: 15 October 2026 Published: 26 October 2026
MSC : 30C45, 30C80

In the paper, we investigate the upper bounds of the second and third Hankel determinants for bounded turning functions linked with a strip domain, whose results are sharp. We also obtain the sharp upper bounds of the second-order Hankel determinants of logarithmic coefficients. Finally, we provide the sharp upper bounds of the third-order Hankel determinant of inverse functions, as well as the sharp upper bounds of the second-order Hankel determinants of inverse logarithmic coefficients. All the other results are accurate, except for the estimation of the fourth logarithmic coefficient.
- univalent functions,
- Hankel determinants,
- bounded turning functions,
- logarithmic coefficients,
- inverse functions
Citation: Dong Guo, Zongtao Li, Xi Luo. On coefficient problems for bounded turning functions associated with a strip domain[J]. AIMS Mathematics, 2026, 11(10): 34884-34906. doi: 10.3934/math.20261358

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Abstract

In the paper, we investigate the upper bounds of the second and third Hankel determinants for bounded turning functions linked with a strip domain, whose results are sharp. We also obtain the sharp upper bounds of the second-order Hankel determinants of logarithmic coefficients. Finally, we provide the sharp upper bounds of the third-order Hankel determinant of inverse functions, as well as the sharp upper bounds of the second-order Hankel determinants of inverse logarithmic coefficients. All the other results are accurate, except for the estimation of the fourth logarithmic coefficient.

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