Stability and bifurcations of limit cycles of the equator in a class of cubic polynomial systems.
After a short summary of the theory of real planar polynomial systems of autonomous differential equations, the authors consider a special class of cubic systems with an equilibrium of focal type at infinity. The recursive calculation of focal values (partly by MATHEMATICA) allows to create an example with 6 limit cycles in a neighborhood of infinity.
scientific article; zbMATH DE number 2017122