Multiple solutions for nonlinear Sturm-Liouville differential equations with possibly negative variable coefficients (Q2096687)

In this paper, the authors studied the multiplicity of solutions for a parameter-dependent boundary value problem with a Sturm-Liouville second order differential equation and Dirichlet conditions. By requiring a suitable behavior on the nonlinearity, they determined an interval of parameter \(\lambda\) for which the problem admits three or infinitely many solutions. The main novelty of this paper is that they applied results of multiple critical points to complete Sturm-Liouville equations where you can have also negative coefficients.