A generalized vector-valued variational principle in Fréchet spaces

Abstract

In the framework of Frechet spaces, we give a generalized vector-valued Ekeland’s variational principle, where the perturbation involves the subadditive functions of countable generating semi-norms. By modifying and developing the method of Cammaroto and Chinni, we obtain a density theorem on extremal points of the vector-valued variational principle, which extends and improves the related known results.