Minimax Theorems

Devoted to minimax theorems and their applications to partial differential equations, this text presents these theorems in a simple and unified way, starting from a quantitative deformation lemma. Many applications are given to problems dealing with lack of compactness, especially problems with critical exponents and existence of solitary waves. There are also recent results and some unpublished material, such as a treatment of the generalized Kadomtsev-Petviashvili equation.