On nonsmooth multivalent guiding functions (Q1776222)

The method of guiding functions developed by Krasnosel'skii, Perov, Bobylev, and others is one of the most efficient tools for establishing the existence of periodic oscillations. In the framework of this method, the guiding potentials are usually assumed to be continuously differentiable, which is restrictive for application in many cases. The paper shows a generalization of the method of multivalent vector guiding functions to the nonsmooth case.