The Bifurcation of Limit Cycle for a Class of Cubic System with Two Imaginary Invariant Line
一类具有二虚不变直线的三次系统的极限环与分支

This paper considers the bifurcation of limit cycle of a class of cubic system with two imaginary invariant line, and gives the focus valus of each order at O(0,0). It is proved that the system with δlmn=0 has at most one limit cycle surrounding O. With the bifurcation theory, the authors give the bifurcation curve of homoclinic cycle and semistable cycle. It means that the system has at most two limit cycles surrounding O