Functional Invariants in Semilocal Bifurcations

In [7] an open set of structurally unstable families of vector fields on a sphere was constructed. More precisely, a vector field with a degeneracy of codimension three was discovered whose bifurcation in a generic three-parameter family has a numeric invariant. This vector field has a polycycle and two saddles, one inside and one outside this polycycle; one separatrix of the outside saddle winds towards the polycycle and one separatrix of the inside saddle winds from it. Families with functional invariants were constructed also. In [2] a hyperbolic polycycle with five vertices and no saddles outside it was constructed whose bifurcations in its arbitrary narrow neighborhood (semilocal bifurcations in other words) have a numeric invariant and thus are structurally unstable. This paper deals with semilocal bifurcations. A hyperbolic polycycle with nine edges is constructed whose semilocal bifurcation in an open set of nine-parameter families has a functional invariant.

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Journal
Regular and Chaotic Dynamics
Published
2025-08-01
DOI
https://doi.org/10.1134/s1560354725040112
Primary Topic
Advanced Differential Equations and Dynamical Systems
Type
article
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Functional Invariants in Semilocal Bifurcations

Yu. Ilyashenko
Regular and Chaotic Dynamics
Advanced Differential Equations and Dynamical Systems
article

Functional Invariants in Semilocal Bifurcations

Yu. Ilyashenko
article en

Abstract

In [7] an open set of structurally unstable families of vector fields on a sphere was constructed. More precisely, a vector field with a degeneracy of codimension three was discovered whose bifurcation in a generic three-parameter family has a numeric invariant. This vector field has a polycycle and two saddles, one inside and one outside this polycycle; one separatrix of the outside saddle winds towards the polycycle and one separatrix of the inside saddle winds from it. Families with functional invariants were constructed also. In [2] a hyperbolic polycycle with five vertices and no saddles outside it was constructed whose bifurcations in its arbitrary narrow neighborhood (semilocal bifurcations in other words) have a numeric invariant and thus are structurally unstable. This paper deals with semilocal bifurcations. A hyperbolic polycycle with nine edges is constructed whose semilocal bifurcation in an open set of nine-parameter families has a functional invariant.

Regular and Chaotic DynamicsVol. 30(4)
National Research University Higher School of Economics (RU), Independent University of Moscow (RU)
Openalex Percentile: Top 74%
Advanced Differential Equations and Dynamical Systems
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