Heinz Werner Engl – författare

Driven by the needs of applications both in sciences and in industry, the field of inverse problems has become a growing area in applied mathematics. This book starts with an overview over some classes of inverse problems of practical interest. Inverse problems typically lead to mathematical models that are ill-posed in the sense of Hadamard. Especially, their solution is unstable under data perturbations, so that special numerical methods that can cope with these instabilities, so-called regularization methods, have to be developed. This book is devoted to the mathematical theory of regularization methods and is intended to give an up-to-date account of the currently available results about regularization methods both for linear and for nonlinear ill-posed problems. Both continuous and iterative regularization methods are considered in detail with special emphasis on the development of parameter choice and stopping rules which lead to optimal convergence rates.

In the last two decades, the field of inverse problems has certainly been one of the fastest growing areas in applied mathematics. This growth has largely been driven by the needs of applications both in other sciences and in industry. In Chapter 1, we will give a short overview over some classes of inverse problems of practical interest. Like everything in this book, this overview is far from being complete and quite subjective. As will be shown, inverse problems typically lead to mathematical models that are not well-posed in the sense of Hadamard, i.e., to ill-posed problems. This means especially that their solution is unstable under data perturbations. Numerical meth­ ods that can cope with this problem are the so-called regularization methods. This book is devoted to the mathematical theory of regularization methods. For linear problems, this theory can be considered to be relatively complete and will be de­ scribed in Chapters 2 - 8. For nonlinear problems, the theory is so far developed to a much lesser extent. We give an account of some of the currently available results, as far as they might be of lasting value, in Chapters 10 and 11. Although the main emphasis of the book is on a functional analytic treatment in the context of operator equations, we include, for linear problems, also some information on numerical aspects in Chapter 9.

Dieses Lehrbuch behandelt zunächst den klassischen Stoff wie Riesz- und Fredholmtheorie in funktionalanalytischer Darstellung. Ein Schwerpunkt ist die Anwendung von Methoden und Ergebnissen aus der Theorie der Integralgleichungen auf gewöhnliche und partielle Differentialgleichungen. Neben der Behandlung der analytischen Aspekte wird auch auf die numerische Lösung von Integralgleichungen eingegangen. Spezifisch für das Buch sind eine ausführliche Behandlung von Integralgleichungen 1. Art, wie sie bei der Modellierung inverser Probleme auftreten, und ein Kapitel über nichtlineare Integralgleichungen, das bis zu den Grundlagen der Verzweigungstheorie vordringt. Auch stark singuläre Gleichungen werden behandelt. Das Lehrbuch wendet sich an Studenten, die die grundlegende Analysis-Ausbildung, inklusive der Grundlagen der linearen Funktionalanalysis, absolviert haben.