On the Existence of Periodic Solutions for Nonlinear Ordinary Di erential Equations


1 Department of Mathematical Sciences,Sharif University of Technology

2 Department of Mathematics,Sharif University of Technology


In this paper, the existence of periodic solutions of autonomous ordinary di erential equations of
a 4th and 5th order is investigated. The method used is based on the Brower's degree theorem
using the homotopy invariant a property of a topological degree.