Nontrivial periodic solutions for delay differential systems via Morse theory Original Research Article

The existence of the nontrivial periodic solutions to the system of delay differential equations equation(1.1) x′(t)=−f(x(t−τ))x′(t)=−f(x(t−τ)) Turn MathJax on is investigated, where View the MathML sourcex∈RN, View the MathML sourcef∈C(RN,RN). We prove several new existence results via Morse theory and the Galerkin methods.