Аннотация:
We classify the family of planar quadratic differential systems with a center of symmetry and two invariant straight lines according to the topology of their phase portraits. The case of the existence of simple infinite singular points is only considered. For each of the obtained distinct topological classes we give necessary and sufficient conditions in terms of algebraic invariants and comitants. The program was implemented for computer calculations.
Ключевые слова и фразы:quadratic differential system, invariant line, phase portrait, limit cycle.