A minimax inequality and its applications to ordinary differential equations

The aim of this paper is to investigate the minimax inequality which plays a fundamental role in the critical points theorem of B. Ricceri below. Equivalent formulations are shown, and characterization is proved in particular for a special class of functionals. As an application, a multiplicity result for an ordinary Dirichlet problem is emphasized.  2002 Elsevier Science (USA). All rights reserved