关于极限环判断的一个注记

A Note on the Judgment of Limit Cycles

摘要: 孤立的周期解中的孤立意味着，在它的邻域内既不存在别的周期解，也不存在系统的奇点。文中举例说明了在平面驻定系统右端函数是解析的情形下，环域中的闭轨并不都是极限环。所举的例子中，周期解上存在奇点。

Abstract: Isolation in isolated periodic solutions implies that the system neither exists other periodic solu-tions nor exists singular points of the system in its neighborhood. We give examples to illustrate that the closed trajectories in an annular region are not all limit cycles, although the right-side functions are analytic functions. In our case, there are singular points in the periodic solution.