On the cyclicity of Kolmogorov polycycles
Marín Pérez, David (Universitat Autònoma de Barcelona. Departament de Matemàtiques)
Villadelprat Yagüe, Jordi (Universitat Autònoma de Barcelona. Departament de Matemàtiques)
Centre de Recerca Matemàtica

Date:	2022
Abstract:	In this paper we study planar polynomial Kolmogorov's differential systems Xμ{x˙=f(x,y;μ),y˙=g(x,y;μ), with the parameter μ varying in an open subset Λ⊂RN. Compactifying Xμ to the Poincaré disc, the boundary of the first quadrant is an invariant triangle Γ, that we assume to be a hyperbolic polycycle with exactly three saddle points at its vertices for all μ∈Λ. We are interested in the cyclicity of Γ inside the family {Xμ}μ∈Λ, i. e. , the number of limit cycles that bifurcate from Γ as we perturb μ. In our main result we define three functions that play the same role for the cyclicity of the polycycle as the first three Lyapunov quantities for the cyclicity of a focus. As an application we study two cubic Kolmogorov families, with N=3 and N=5, and in both cases we are able to determine the cyclicity of the polycycle for all μ∈Λ, including those parameters for which the return map along Γ is the identity.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca
Subject:	Limit cycle ; Polycycle ; Cyclicity ; Asymptotic expansion
Published in:	Electronic Journal of Qualitative Theory of Differential Equations, Vol. 35 (2022) , p. 1-31, ISSN 1417-3875

DOI: 10.14232/ejqtde.2022.1.35

31 p, 607.7 KB

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