Notes on Multiple Periodic Solutions for Second-order Discrete Hamiltonian System

Liang Ding, Jinlong Wei

By a new orthogonal direct sum decomposition $E_M=Y\oplus Z$, which $Z$ is related to $\hat{I}”u_i(i=1,2,3,....,M)$, and a new functional $I(u)$, the method in [2] is improved to ob…