Versal deformations of $D_q$-invariant 2-parameter families of planar vector fields
Tom 62 / 1995
Annales Polonici Mathematici 62 (1995), 265-281 DOI: 10.4064/ap-62-3-265-281
The paper deals with 2-parameter families of planar vector fields which are invariant under the group $D_q$ for q ≥ 3. The germs at z = 0 of such families are studied and versal families are found. We also give the phase portraits of the versal families.