Boundary Value Problems
Volume 2006 (2006), Article ID 25104, 9 pages
doi:10.1155/BVP/2006/25104
Periodic solutions of second-order nonautonomous dynamical systems
Department of Mathematics, University of California, Irvine 92697-3875, CA, USA
Received 13 March 2006; Revised 10 May 2006; Accepted 15 May 2006
Copyright © 2006 Martin Schechter. 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
We study the existence of periodic solutions for second-order
nonautonomous dynamical systems. We give four sets of hypotheses
which guarantee the existence of solutions. We were able to weaken
the hypotheses considerably from those used previously for such
systems. We employ a new saddle point theorem using linking
methods.