During the last few years the field of nonlinear problems has undergone greatdevelopment. This book consisting of the updated Grundlehren volume 252 by theautho... » 

During the last few years the field of nonlinear problems has undergone greatdevelopment. This book consisting of the updated Grundlehren volume 252 by theauthor and of a newly written part deals with some important geometricproblems that are of interest to many mathematicians and scientists but haveonly recently been partially solved. Each problem is explained uptodateresults are given and proofs are presented. Thus the reader is given accessfor each specific problem to its present status of solution as well as to themost uptodate methods for approaching it. The main objective of the book isto explain some methods and new techniques and to apply them. It deals withsuch important subjects as variational methods the continuity methodparabolic equations on fiber. «