Sign Changing Critical Points for Locally Lipschitz Functionals

In this paper, some existence results for sign-changing critical points of locally Lipschitz functionals in real Banach space are obtained by the method combining the invariant sets of descending ow method with a quantitative deformation. First we assume the locally Lipschitz functionals to be outwardly directed on the the boundary of some closed convex sets of the real Banach space. By using the relation between the critical points on the Banach space and those of the closed convex sets, we construct a quantitative deformation lemma, and then we obtain some linking type of critical points theorems. These theoretical results can be applied to the study of the existence of sign-changing solutions for differential inclusion problems. In contrast with the related results in the literatures, the main results of this paper relax the requirement that the functional being of C1 continuous to locally Lipschitz.