具有星形奇点或中心的二次系统不存在极限环的新证明

The proof of non-existence of the limit cycle for RQDS haviug a stellar node or a centre

本文用无切线段和Dulac函数,以极少的篇幅,将标题所述的定理给出新的证明。

In this paper, using the without contact technique and Dulac functions, We give a short proof of the theorems showing in the article.