New solutions of the Poincaré Center Problem in degree 3
Hans-Christian von Bothmer
TL;DR
This work advances the Poincaré center problem for planar polynomial vector fields by integrating Darboux integrability with the inverse problem for plane curves. It introduces an invariant based on singularity data, enabling a quasi-homogeneous–based criterion to certify Darboux integrability and construct first principal components of the degree $3$ center variety. Through equi-singular curve configurations and careful dimension counts, the authors produce several explicit $9$-dimensional families that form new codimension $9$ components, some of which extend known Steiner ideals and Żoła̧dek’s families. The combination of theoretical framework and computer-assisted constructions significantly deepens the understanding and classification of centers in degree $3$, offering both new tools and concrete examples for broader center-variety analysis.
Abstract
Let $ω$ be a plane autonomous system and C its configuration of algebraic integral curves. If the singularities of C are quasi-homogeneous we we present new criteria that guarantee Darboux integrability. We use this to construct previously unknown components of the center variety in degree 3.
