包围多个奇点的极限环的不存在性与唯二性

EXISTENCE OF AT MOST TWO LIMIT CYCLES SURROUNDING MULTIPLE SINGULAR POINTS

本文给出一类非线性方程没有及至多有两个包围三个奇点的极限环的若干条件。

In this paper sufficient conditions for a nonlinear equation to have at most two limit cycles surrounding three singular points are given. As an application, bifurcations of limit cycles of several polynomial systems are studied.