Abstract
This volume is dedicated to the memory of Gaetano Fichera as a sign of recognition for his outstanding research in the field of Italian and international mathematics. Gaetano Fichera was one of the great Italian masters of mathematics following in the wake of such others as Enrico Betti, Eugenio Beltrami, Vito Volterra, Eugenio Elia Levi, Tullio Tricomi, Renato Caccioppoli, who have contributed to render the field of Italian mathematics as one of the most brilliant and creative in the world