Abstract and Applied Analysis
Volume 2010 (2010), Article ID 620438, 10 pages
doi:10.1155/2010/620438
Research Article

Infinitely Many Periodic Solutions for Nonautonomous Sublinear Second-Order Hamiltonian Systems

Peng Zhang1 and Chun-Lei Tang2

1Department of Mathematics, ZunYi Normal College, ZunYi 563002, China
2Department of Mathematics, School of Mathematics and Statistics, Southwest University, Chongqing 400715, China

Received 6 February 2010; Accepted 7 June 2010

Academic Editor: Jean Mawhin

Copyright © 2010 Peng Zhang and Chun-Lei Tang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Two sequences of distinct periodic solutions for second-order Hamiltonian systems with sublinear nonlinearity are obtained by using the minimax methods. One sequence of solutions is local minimum points of functional, and the other is minimax type critical points of functional. We do not assume any symmetry condition on nonlinearity.