Advances in Difference Equations 
Volume 2008 (2008), Article ID 247071, 11 pages
doi:10.1155/2008/247071
Research Article

Existence Theorems of Periodic Solutions for Second-Order Nonlinear Difference Equations

Xiaochun Cai1 and Jianshe Yu2

 1College of Statistics, Hunan University, Changsha, Hunan 410079, China
2College of Mathematics and Information Science, Guangzhou University, Guangzhou 510405, China
Received 14 August 2007; Accepted 14 November 2007

Recommended by Patricia J. Y. Wong

Abstract

The authors consider the second-order nonlinear difference equation of the type Δ(pn(Δxn−1)δ)+qnxnδ=f(n,xn),n∈ℤ, using critical point theory, and they obtain some new results on the existence of periodic solutions.