In this paper, we investigate the existence of solution for differential systems involving a Laplacian operator which incorporates as a special case the well-known Laplacian operator. In this purpose, we use a variational method which relies on Szulkin’s critical point theory. We obtain the existence of solution when the corresponding Euler–Lagrange functional is coercive.
"A Variational Method for Multivalued Boundary Value Problems." Abstr. Appl. Anal. 2020 1 - 8, 2020. https://doi.org/10.1155/2020/8463263