CBMS Regional Conference Series in Mathematics 1986; 100 pp; softcover Number: 65 Reprint/Revision History: reprinted with corrections 1988 ISBN10: 0821807153 ISBN13: 9780821807156 List Price: US$25 Member Price: US$20 All Individuals: US$20 Order Code: CBMS/65
 The book provides an introduction to minimax methods in critical point theory and shows their use in existence questions for nonlinear differential equations. An expanded version of the author's 1984 CBMS lectures, this volume is the first monograph devoted solely to these topics. Among the abstract questions considered are the following: the mountain pass and saddle point theorems, multiple critical points for functionals invariant under a group of symmetries, perturbations from symmetry, and variational methods in bifurcation theory. The book requires some background in functional analysis and differential equations, especially elliptic partial differential equations. It is addressed to mathematicians interested in differential equations and/or nonlinear functional analysis, particularly critical point theory. Table of Contents  An overview
 The mountain pass theorem and some applications
 Some variants of the mountain pass theorem
 The saddle point theorem
 Some generalizations of the mountain pass theorem
 Applications to Hamiltonian systems
 Functionals with symmetries and index theorems
 Multiple critical points of symmetric functionals: problems with constraints
 Multiple critical points of symmetric functionals: the unconstrained case
 Pertubations from symmetry
 Variational methods in bifurcation theory
