On the Morse critical groups for indefinite sublinear elliptic problems Original Research Article

We consider the Dirichlet problem for the equation −Δu=αu+m(x)u|u|q−2+g(x,u), where q∈(1,2) and m changes sign. We prove that the Morse critical groups at zero of the energy functional of the problem are trivial. As a consequence, existence and bifurcation of nontrivial solutions of the problem are established.