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JOURNALS // Moscow Mathematical Journal // Archive

Mosc. Math. J., 2020 Volume 20, Number 2, Pages 375–404 (Mi mmj769)

Orbital Chen theorem for germs of $\mathcal{C}^{\infty}$ vector fields with degenerate singularity

Jessica Jaurez Rosas, Laura Ortiz-Bobadilla

Instituto de Matemáticas, Universidad Nacional Autónoma de México (UNAM), Área de la Investigación Científica, Circuito exterior, Ciudad Universitaria, 04510, Ciudad de México, México

Abstract: We consider germs of $\mathcal{C}^{\infty}$ vector fields in $(\mathbb{R}^2, 0)$ with degenerate non-dicritic singularity (having ($n-1$)-jet zero and non-zero $n$-jet) and their corresponding foliations. Under some natural hypothesis we prove that the orbital formal equivalence of any two such vector fields implies their orbital $\mathcal{C}^{\infty}$ equivalence (and thus the $\mathcal{C}^{\infty}$ equivalence of the corresponding foliations). This result generalizes Chen Theorem for foliations defined by generic $\mathcal{C}^{\infty}$ germs of vector fields in $(\mathbb{R}^2, 0)$ having hyperbolic singularity.

Key words and phrases: formal normal forms, foliations, flat vector fields, rigidity.

MSC: 34C07, 34C05, 34C08

Language: English

DOI: 10.17323/1609-4514-2020-20-2-375-404



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© Steklov Math. Inst. of RAS, 2025