Flat solutions of some non-Lipschitz autonomous semilinear equations may be stable for $N\ge 3$

Abstract

We prove that flat ground state solutions ($i.e.$ minimizing the energy and with gradient vanishing on the boundary of the domain) of the Dirichlet problem associated to some semilinear autonomous elliptic equations with a strong absorption term given by a non-Lipschitz function are unstable for dimensions $N=1,2$ and they can be stable for $N\ge 3$ for suitable values of the involved exponents.

30 pages, 3 figures