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    • Keywords


      Upper solution; lower solution; order interval; truncation function; pseudomonotone operator; coercive operator; extremal solution; Yosida approximation; nonsmooth Palais-Smale condition; critical point; eigenvalue problem

    • Abstract


      In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all ℝ. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of ℝ. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).

    • Author Affiliations


      Antonella Fiacca1 Nikolaos Matzakos2 Nikolaos S Papageorgiou2 Raffaella Servadei1

      1. Department of Mathematics, University of Perugia, Via Vanvitelli 1, Perugia - 06123, Italy
      2. Department of Mathematics, National Technical University, Zografou Campus, Athens - 15780, Greece
    • Dates

  • Proceedings – Mathematical Sciences | News

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