Martin Väth – författare

This monograph aims to give a self-contained introduction into the whole field of topological analysis: Requiring essentially only basic knowledge of elementary calculus and linear algebra, it provides all required background from topology, analysis, linear and nonlinear functional analysis, and multivalued maps, containing even basic topics like separation axioms, inverse and implicit function theorems, the Hahn-Banach theorem, Banach manifolds, or the most important concepts of continuity of multivalued maps. Thus, it can be used as additional material in basic courses on such topics. The main intention, however, is to provide also additional information on some fine points which are usually not discussed in such introductory courses.The selection of the topics is mainly motivated by the requirements for degree theory which is presented in various variants, starting from the elementary Brouwer degree (in Euclidean spaces and on manifolds) with several of its famous classical consequences, up to a general degree theory for function triples which applies for a large class of problems in a natural manner. Although it has been known to specialists that, in principle, such a general degree theory must exist, this is the first monograph in which the corresponding theory is developed in detail.

Dieses Lehrbuch gibt eine Einführung in Theorie, Methoden und Anwendungen der Funktionalanalysis. Im Unterschied zur Analysis in den Anfängervorlesungen arbeitet man in der Funktionalanalysis vor allem in unendIichdimensionalen Räumen. Dort treten viele überraschende Phänomene auf, die im Endlichdimensionalen "verborgen" bleiben. Eine herausragende Rolle spielt der Begriff der Kompaktheit, der in vielen Anwendungen auf Differentialgleichungen, Integralgleichungen und Fixpunktprobleme von Wichtigkeit ist und sozusagen eine "Brücke" zwischen dem Endlichen und Unendlichen bildet.Dies ist das erste Buch, das eine elementare Einführung sowohl in die Lineare als auch in die Nichtlineare Funktionalanalysis 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 Überlegungen.

Ideal spaces are a very general class of normed spaces of measurable functions, which includes e.g. Lebesgue and Orlicz spaces. Their most important application is in functional analysis in the theory of (usual and partial) integral and integro-differential equations. The book is a rather complete and self-contained introduction into the general theory of ideal spaces. Some emphasis is put on spaces of vector-valued functions and on the constructive viewpoint of the theory (without the axiom of choice). The reader should have basic knowledge in functional analysis and measure theory.