Boundary Value Problems
Volume 2006 (2006), Article ID 25104, 9 pages

Periodic solutions of second-order nonautonomous dynamical systems

Martin Schechter

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.


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.