Electronic Journal of Differential Equations,
Conference 09 (2002), pp. 93-106.

Title: Existence and multiplicity of nontrivial solutions for double resonance
  semilinear elliptic problems.

Authors: Abdel R. El Amrouss (Faculty of sciences Oujda, Morocco)
 
Abstract: 
  We consider resonance problems at an arbitrary eigenvalue of the
  Laplacien. We prove the existence of nontrivial solutions for some
  semilinear elliptic Dirichlet boundary values problems. We also
  obtain two nontrivial solutions by using Morse theory.

Published December 28, 2002.
Math Subject Classifications: 58E05, 35J65, 56J20.
Key Words: Variational elliptic problem; resonance; critical group;
  Morse theory; minimax method.