Abstract
By using the least action principle and the minimax methods, some existence theorems are obtained for periodic solutions of second-order discrete Hamiltonian systems:
Acknowledgement
This project is partially supported by the NNSF (No. 10771215) of China and supported by the Graduate degree thesis Innovation Foundation of Central South University (No: 3960-71131100014) and supported by the Outstanding Doctor degree thesis Implantation Foundation of Central South University (No: 2008yb032).