Monotonicity of the period map of a non-Hamiltonian center
The authors prove that the periodic map of \(\ddot x- ax\dot x+ x^ 3= 0\) with \(a^ 2< 8\), is monotonically decreasing. As an application, it is obtained that the respective Dirichlet boundary value problem for two points has either a unique solution or no solution at all while the Neumann boundary value problem has a unique solution.
scientific article; zbMATH DE number 724156