We consider a general periodic system driven by a nonlinear, nonhomogeneous differential operator, with a maximal monotone term which is not defined everywhere. Using a topological approach based on Leray-Schauder alternative principle, we show the existence of a periodic solution.
"Nonlinear periodic system with unilateral constraints." Topol. Methods Nonlinear Anal. 54 (2B) 871 - 885, 2019. https://doi.org/10.12775/TMNA.2019.062