一类二阶中立型泛函微分方程周期解的个数估计

A Estimate for Number Multiple Periodic Solutions to a Class Neutral Differential Equations

本文通过变分原理和Z_2不变群指标,得出下述二阶中立型泛函微分方程(cx(t)+x(t-T)+cx(t-2T))"-x(t-T)+λf(t,x(t),x(t-T),x(t-2T))=0周期解个数的下界估计.

By means of variational structure and Z2 group index theory, we obtain a estimate for number of multiple periodic solutions to second-order neutral functional differential equations （cx（t）＋x（t-τ）＋cx（t-2τ））＂-x（t-τ）＋λf（t,x（t）,x（t-τ）,x（t-2τ））=0.