Partial Differential Equations And The Calculus of Variations

Since the birth of the calculus of variations, researchers have discovered that variational methods, when they apply, can obtain better results than most other methods. Moreover, they apply in a very large number of situations. It was realized many years ago that the solutions of a great number of problems are in effect critical points of functionals. Critical Point Theory and Its Applications presents some of the latest research in the area of critical point theory. Researchers have obtained many new results recently using this approach, and in most cases comparable results have not been obtained with other methods. This book describes the methods and presents the newest applications.

Cet ouvrage est issu d’un cours de Master 2 enseigné à l’UPMC entre 2004 et 2007. Nous y présentons une sélection de techniques mathématiques orientées vers la résolution des équations aux dérivées partielles elliptiques semi-linéaires et quasi-linéaires.

Cet ouvrage est issu d’un cours de Master 2 enseigné à l’UPMC entre 2004 et 2007. Nous y présentons une sélection de techniques mathématiques orientées vers la résolution des équations aux dérivées partielles elliptiques semi-linéaires et quasi-linéaires.

Problems linking the shape of a domain or the coefficients of an elliptic operator to the sequence of its eigenvalues are among the most fascinating of mathematical analysis. In this book, we focus on extremal problems. For instance, we look for a domain which minimizes or maximizes a given eigenvalue of the Laplace operator with various boundary conditions and various geometric constraints. We also consider the case of functions of eigenvalues. We investigate similar questions for other elliptic operators, such as the Schrödinger operator, non homogeneous membranes, or the bi-Laplacian, and we look at optimal composites and optimal insulation problems in terms of eigenvalues.