当中心邻域的闭轨周期为常数时,该中心称为等时中心.解决等时中心问题的主要难点在于横截交换系统的计算.为了减少计算量,对于时间可逆的解析微分系统,给出了系统具有等时中心的两个充要条件,为建立等时中心条件推导的直接方法作理论上的准备.
A center is called an isochronous center if those periodic orbits in some neighbourhood have the same period. The main difficulty in proving isochronicity is to find corresponding transversal commuting system. To reduce the computations, this paper gives two necessary and sufficient conditions for isoehronicity of time-reversible systems. These two conditions are theoretically helpful for constructing isochronicity in a direct way.