Jurgen Appell – författare

A self-contained account of integro-differential equations of the Barbashin type and partial integral operators. It presents the basic theory of Barbashin equations in spaces of continuous or measurable functions, including existence, uniqueness, stability and perturbation results. The theory and applications of partial integral operators and linear and nonlinear equations is discussed. Topics range from abstract functional-analytic approaches to specific uses in continuum mechanics and engineering.

The book contains a collection of 21 original research papers which report on recent developments in various fields of nonlinear analysis. The collection covers a large variety of topics ranging from abstract fields such as algebraic topology, functional analysis, operator theory, spectral theory, analysis on manifolds, partial differential equations, boundary value problems, geometry of Banach spaces, measure theory, variational calculus, and integral equations, to more application-oriented fields like control theory, numerical analysis, mathematical physics, mathematical economy, and financial mathematics. The book is addressed to all specialists interested in nonlinear functional analysis and its applications, but also to postgraduate students who want to get in touch with this important field of modern analysis. It is dedicated to Alfonso Vignoli who has essentially contributed to the field, on the occasion of his sixtieth birthday.

In view of the eminent importance of spectral theory of linear operators in many fields of mathematics and physics, it is not surprising that various attempts have been made to define and study spectra also for nonlinear operators. This book provides a comprehensive and self-contained treatment of the theory, methods, and applications of nonlinear spectral theory. The first chapter briefly recalls the definition and properties of the spectrum and several subspectra for bounded linear operators. Then some numerical characteristics for nonlinear operators are introduced which are useful for describing those classes of operators for which there exists a spectral theory. Since spectral values are closely related to solvability results for operator equations, various conditions for the local or global invertibility of a nonlinear operator are collected in the third chapter. The following two chapters are concerned with spectra for certain classes of continuous, Lipschitz continuous, or differentiable operators. These spectra, however, simply adapt the corresponding definitions from the linear theory which somehow restricts their applicability. Other spectra which are defined in a completely different way, but seem to have useful applications, are defined and studied in the following four chapters. The remaining three chapters are more application-oriented and deal with nonlinear eigenvalue problems, numerical ranges, and selected applications to nonlinear problems. The only prerequisite for understanding this book is a modest background in functional analysis and operator theory. It is addressed to non-specialists who want to get an idea of the development of spectral theory for nonlinear operators in the last 30 years, as well as a glimpse of the diversity of the directions in which current research is moving.

The authors present a completely new and highly application-oriented field of nonlinear analysis. The work covers the theory of non-smooth input-output systems and presents various methods to non-standard applications in mathematics and physics. A particular focus lies on hysteresis and relay phenomena, electric circuits with diode nonlinearities, and biological systems with constraints.

Dies ist das erste Lehrbuch, das eine elementare Einfuhrung sowohl in die Lineare als auch in die Nichtlineare Analysis gibt und viele Wechselwirkungen zwischen beiden diskutiert. Ein besonderer Vorteil des Buches liegt auch darin, dass es oft von Beispielen und Gegenbeispielen ausgeht, nicht von abstrakten Uberlegungen.

Das Buch gibt in sechs Kapiteln eine Einführung in die Theorie der reellen Funktionen einer und mehrerer Variabler. Hierbei stehen nicht so sehr abstrakte Ergebnisse im Vordergrund, sondern es werden besonders viele Beispiele und Gegenbeispiele präsentiert, anhand derer man die Bedeutung mathematischer Sätze besonders gut erkennen kann.In den ersten drei Kapiteln werden die wesentlichen Ergebnisse über stetige, differenzierbare und integrierbare Funktionen zusammengestellt. Das vierte Kapitel geht etwas über den üblichen Analysisstoff hinaus und ist "merkwürdigen" Teilmengen der reellen Achse und zugehörigen Funktionen gewidmet. Funktionen mehrerer Variabler werden im fünften und sechsten Kapitel behandelt.Über die starke Betonung von Beispielen hinaus ist ein weiteres Merkmal des Buches die große Anzahl von Übungsaufgaben am Ende jedes Kapitels. Es ist daher auch sehr gut als Aufgabensammlung zur Prüfungsvorbereitung geeignet.

This volume contains a collection of 21 original research papers which report on developments in various fields of nonlinear analysis. The collection covers a large variety of topics ranging from abstract fields such as algebraic topology, functional analysis, operator theory, spectral theory, analysis on manifolds, partial differential equations, boundary value problems, geometry of Banach spaces, measure theory, variational calculus, and integral equations, to more application-oriented fields.