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Introduction to various aspects of degree theory in Banach spaces. (English) Zbl 0597.47040
Mathematical Surveys and Monographs, No. 23. Providence, R.I.: American Mathematical Society (AMS). VI, 242 p. \$ 60.00 (1986).
This book is devoted to some aspects of the theory of degree for different classes of nonlinear mappings in Banach spaces; the choice of results and constructions in this book is determined partly by the fact that the book is written from the point of view of an analyst; partly by the author’s desire to throw light on the theory from various angles, and partly by the author’s taste.
The book contains 9 chapters and 2 applications: function-analytic preliminaries (Banach spaces and different classes of nonlinear mappings, differentiability of mappings, Dugundji’s extension theorem and so on), the Leray-Schauder degree for differentiable maps, the Leray-Schauder degree for not necessarily differentiable maps, the Poincaré-Bohl theorem and some of its applications, the product theorem and some of its consequences (the invariance of the domain and the Jordan-Leray theorem), the finite-dimensional case (simplicial approximations in the degree theory), on spheres (the degree theory for mappings from one sphere $$S_ 1^ n$$ into another $$S_ 2^ n)$$, some extension and homotopy theorems (Hopf-Krasnoselskii extension theorems and some near results), the Borsuk theorem and some of its consequences; appendix 1 contains the proof of the linear homotopic theorem, appendix 2 gives the proof of the Sard- Smale theorem.
This book will be interesting to all analysts that apply geometrical and topological methods in their investigations; it can be used for acquaintance with some problems in the field.
Reviewer: P.Zabrejko

##### MSC:
 47J05 Equations involving nonlinear operators (general) 47-02 Research exposition (monographs, survey articles) pertaining to operator theory 46G05 Derivatives of functions in infinite-dimensional spaces