Existence of non-collision periodic solutions for second order singular dynamical systems
The author studies the existence of periodic solutions for a system of the type \[ \ddot x + a(t) x = f(t,x) + e(t) \] when the nonlinearity has a singularity of repulsive type in the origin. The assumptions in the main theorem are rather involved, but some interesting examples of applications are given.
scientific article; zbMATH DE number 5794102