Analytic classification of resonant saddles and foci. (English) Zbl 0596.34021

Singularities and dynamical systems, Proc. Int. Conf., Heraklion/Greece 1983, North-Holland Math. Stud. 103, 109-135 (1985).
[For the entire collection see Zbl 0547.00033.]
The authors classify, up to local analytic transformation of \({\mathbb{R}}^ 2\), the phase portraits near zero of the differential systems: (1) Saddles: \(\dot x=qx+...,\quad \dot y=-py+... ;\) (2) Foci: \(\dot x=y+...,\quad \dot y=-x+...,\) where p, q are relatively prime positive integers and, in both cases, the dots denote convergent series of order at least two. Some results from formal classification of resonant differential forms are recalled. The basic admission to the classification problem in question consists in the complexification of the real resonant system.
Reviewer: A.Klič


34C20 Transformation and reduction of ordinary differential equations and systems, normal forms
34C05 Topological structure of integral curves, singular points, limit cycles of ordinary differential equations
37C85 Dynamics induced by group actions other than \(\mathbb{Z}\) and \(\mathbb{R}\), and \(\mathbb{C}\)
34M99 Ordinary differential equations in the complex domain


Zbl 0547.00033