How to solve partial differential systems by completing the square. This could well have been the title of this monograph as it grew into a project to develop a s- tematic approach for associating suitable nonnegative energy functionals to a large class of partial differential equations (PDEs) and evolutionary systems. The minima of these functionals are to be the solutions we seek, not because they are critical points (i. e. , from the corresponding Euler-Lagrange equations) but from also - ing zeros of these functionals. The approach can be traced back to Bogomolnyi's trick of "completing squares" in the basic equations of quantum eld theory (e. g. , Yang-Mills, Seiberg-Witten, Ginzburg-Landau, etc. ,), which allows for the deri- tion of the so-called self (or antiself) dual version of these equations. In reality, the "self-dual Lagrangians" we consider here were inspired by a variational - proach proposed - over 30 years ago - by Brezis ' and Ekeland for the heat equation and other gradient ows of convex energies. It is based on Fenchel-Legendre - ality and can be used on any convex functional - not just quadratic ones - making them applicable in a wide range of problems. In retrospect, we realized that the "- ergy identities" satis ed by Leray's solutions for the Navier-Stokes equations are also another manifestation of the concept of self-duality in the context of evolution equations.
Reviews

"The subject of this monograph is related to the relationship between large classes of partial differential equations or evolutionary systems and energy functionals associated with them. Examples include transport equations, porous media equations, and Navier-Stokes evolution equations. ... This well-written book contains a large amount of material. It can be useful for graduate students and researchers interested in modern aspects of the calculus of variations with powerful applications to the qualitative analysis of partial differential equations." (Vicentiu D. Radulescu, zbMATH 1357.49004, 2017)

"The subject of this monograph is related to the relationship between large classes of partial differential equations or evolutionary systems and energy functionals associated with them. ... This well-written book contains alarge amount of material. It can be useful for graduate students and researchers interested in modern aspects of the calculus of variations with powerful applications to the qualitative analysis of partial differential equations." (Vicentiu Radulescu, Mathematical Reviews, Issue 2010 c)



Book Information
ISBN 9780387848969
Author Nassif Ghoussoub
Format Hardback
Page Count 354
Imprint Springer-Verlag New York Inc.
Publisher Springer-Verlag New York Inc.