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ЖУРНАЛЫ // Regular and Chaotic Dynamics // Архив

Regul. Chaotic Dyn., 2025, том 30, выпуск 4, страницы 618–627 (Mi rcd1325)

Special Issue: Celebrating the 75th Birthday of V.V. Kozlov (Issue Editors: Sergey Bolotin, Vladimir Dragović, and Dmitry Treschev)

Functional Invariants in Semilocal Bifurcations

Yulij S. Ilyashenkoab

a IUM, per. Bolshoy Vlasyevskiy 11, 119002 Moscow, Russia
b HSE University, ul. Myasnitskaya 20, 101000 Moscow, Russia

Аннотация: 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.

Ключевые слова: polycycles, semilocal bifurcations, functional invariants

MSC: 37G10, 58K45, 34C23

Поступила в редакцию: 13.05.2025
Принята в печать: 10.07.2025

Язык публикации: английский

DOI: 10.1134/S1560354725040112



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