A Chebyshev criterion for at most two non-zero limit cycles in Abel equations

Fuente: arXiv
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Auteurs principaux: Huang, Jianfeng, Tian, Renhao, Zhao, Yulin
Format: Preprint
Publié: 2025
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author Huang, Jianfeng
Tian, Renhao
Zhao, Yulin
author_facet Huang, Jianfeng
Tian, Renhao
Zhao, Yulin
contents In this paper, we investigate the maximum number of limit cycles of the reduced Abel equation $\dot{x}=A(t)x^{3}+B(t)x^{2}$ on an interval $[0,T]$. The Smale-Pugh problem asks whether this maximum number is bounded in terms of a given class of coefficients. We establish for the first time a Chebyshev criterion, providing a positive answer to the problem when this class spanned by an extended Chebyshev system (ET-system) $\mathcal{F}=\{f_{0},f_{1},f_{2}\}$ on $[0,T)$ with $f_{0}\not=0$. As an application, we prove that the equation has at most three limit cycles (including $x=0$) when the coefficients $A$ and $B$ are both linear trigonometric functions or quadratic polynomials. This reestablishes the result of Yu et al. (J. Differ. Equ., 2024) and improves the work of Bravo et al. (Disc. Cont. Dyn. Syst., 2015 \& J. Differ. Equ., 2024). We also obtain the same maximum number of limit cycles for the equation with trinomial coefficients.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14091
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Chebyshev criterion for at most two non-zero limit cycles in Abel equations
Huang, Jianfeng
Tian, Renhao
Zhao, Yulin
Classical Analysis and ODEs
In this paper, we investigate the maximum number of limit cycles of the reduced Abel equation $\dot{x}=A(t)x^{3}+B(t)x^{2}$ on an interval $[0,T]$. The Smale-Pugh problem asks whether this maximum number is bounded in terms of a given class of coefficients. We establish for the first time a Chebyshev criterion, providing a positive answer to the problem when this class spanned by an extended Chebyshev system (ET-system) $\mathcal{F}=\{f_{0},f_{1},f_{2}\}$ on $[0,T)$ with $f_{0}\not=0$. As an application, we prove that the equation has at most three limit cycles (including $x=0$) when the coefficients $A$ and $B$ are both linear trigonometric functions or quadratic polynomials. This reestablishes the result of Yu et al. (J. Differ. Equ., 2024) and improves the work of Bravo et al. (Disc. Cont. Dyn. Syst., 2015 \& J. Differ. Equ., 2024). We also obtain the same maximum number of limit cycles for the equation with trinomial coefficients.
title A Chebyshev criterion for at most two non-zero limit cycles in Abel equations
topic Classical Analysis and ODEs
url https://arxiv.org/abs/2506.14091