Infinitely Many Solutions of Boundary Value Problems for a Classof Second-Order Ordinary Differential Equations
一类二阶常微分方程边值问题的无穷多个解

By means of variational structure and $Z_2$ group index theory, infinitely many solutions of boundary value problems for second-order ordinary differential equations $$\arraycolsep=1.5pt \left\{\begin{array}{lcl}\displaystyle u'(t)-u(t)+ f(t,u(t))=0,\quad 0-\frac{1}{2}$.