Critical Point Theory and Its Applications

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.

The topics covered in the book include extrema, even valued functionals, weak and double linking, sign changing solutions, Morse inequalities, and cohomology groups. The applications described include Hamiltonian systems, Schrödinger equations and systems, jumping nonlinearities, elliptic equations and systems, superlinear problems and beam equations. Many minimax theorems are established without the use of the (PS) compactness condition.

• Cohomology group
• Homoclinic orbits
• Linking
• Minimum
• Schrödinger equations
• Sign-changing solutions
• calculus
• compactness
• extrema
• partial differential equations
• ordinary differential equations

"Many, often difficult and advanced, examples included into the text form an excellent review of a frontline of actual research in the area. ... In conclusion, the reviewer may recommend the book of Zou and Schechter as an excellent reference for those seeking new as well as well-established techniques in the critical point theory approach to differential equations."

—Zentralblatt Math

"In many variational problems, the functional Phi is strongly indefinite and does not satisfy the Palais-Smale condition. In this book, the authors present some of the latest work which has been done to overcome these difficulties and prove the existence of critical points. They also show how the abstract results can be applied to many problems in ordinary and partial differential equations."

—Mathematical Reviews

• Tsinghua University, Beijing, China

  Wenming Zou

• University of California, Irvine, USA

  Martin Schechter

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