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2002 | Buch

Introduction to Tensor Products of Banach Spaces

verfasst von: Raymond A. Ryan

Verlag: Springer London

Buchreihe : Springer Monographs in Mathematics

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Über dieses Buch

This book is intended as an introduction to the theory of tensor products of Banach spaces. The prerequisites for reading the book are a first course in Functional Analysis and in Measure Theory, as far as the Radon-Nikodym theorem. The book is entirely self-contained and two appendices give addi­ tional material on Banach Spaces and Measure Theory that may be unfamil­ iar to the beginner. No knowledge of tensor products is assumed. Our viewpoint is that tensor products are a natural and productive way to understand many of the themes of modern Banach space theory and that "tensorial thinking" yields insights into many otherwise mysterious phenom­ ena. We hope to convince the reader of the validity of this belief. We begin in Chapter 1 with a treatment of the purely algebraic theory of tensor products of vector spaces. We emphasize the use of the tensor product as a linearizing tool and we explain the use of tensor products in the duality theory of spaces of operators in finite dimensions. The ideas developed here, though simple, are fundamental for the rest of the book.

Inhaltsverzeichnis

Frontmatter
1. Tensor Products
Abstract
In this chapter we study tensor products from a purely algebraic viewpoint. Our approach is to define tensors as functionals that act on bilinear forms. We explain how the tensor product can be seen as a “linearizing space” for bilinear mappings. Tensors can also be viewed as bilinear forms, or as linear mappings and we explore the connections between these ideas. In finite dimensions, tensor products provide a means of understanding the duality of spaces of linear mappings or bilinear forms, either through “tensor duality” or the equivalent “trace duality”. Finally, we look at some examples of tensor products.
Raymond A. Ryan
2. The Projective Tensor Product
Abstract
In this chapter we investigate the simplest way to norm the tensor product of two Banach spaces. The projective tensor product linearizes bounded bilinear mappings just as the algebraic tensor product linearizes bilinear mappings. The projective tensor product derives its name from the fact that it behaves well with respect to quotient space constructions. The projective tensor product of ℓ1 with X gives a representation of the space of absolutely summable sequences in X and projective tensor products with L(µ)lead to a study of the Bochner integral for Banach space valued functions. We also introduce the class of ℒ-spaces, whose finite dimensional structure is like that of ℓ1. We study some techniques that make use of the Rademacher functions, including the Khinchine inequality. Finally, interpreting the elements of a projective tensor product as bilinear forms or operators leads to the introduction of the concept of nuclearity.
Raymond A. Ryan
3. The Injective Tensor Product
Abstract
In this chapter we study the injective norm for tensor products. The injective tensor product gives a representation of Banach spaces of continuous vector valued functions and injective tensor products with L 1 (μ) spaces provide an introduction to the Pettis integral. The duality theory of injective tensor products leads to the introduction of the important classes of integral bilinear forms and operators.
Raymond A. Ryan
4. The Approximation Property
Abstract
In this chapter we introduce the approximation property for Banach spaces. The possession of this property leads to the resolution of several outstanding issues concerning projective and injective tensor products. We then consider the following question: when are the projective or injective tensor products of reflexive spaces themselves reflexive? A satisfactory answer requires the use of the approximation property. Finally, we study tensor products of Banach spaces with Schauder bases.
Raymond A. Ryan
5. The Radon-Nikodým Property
Abstract
In this chapter we introduce the Radon-Nikodým property for Banach spaces. We begin with a study of vector measures, that is, measures with values in a Banach space. Those spaces for which the classical Radon—Nikodým Theorem extends to vector valued measures are said to have the Radon—Nikodým property. The identification of injective and projective tensor products of spaces of scalar measures in terms of spaces of vector measures sheds some light on this property. We then examine the representability of various types of operators on C(K) and L 1(μ) spaces and we uncover some classes of Banach spaces, such as the reflexive spaces and the separable dual spaces, that possess the Radon-;Nikodým property. We also relate the possession of this property to the coincidence of the integral and nuclear operators Finally, we give some applications of the Radon-Nikodým property, including the Principle of Local Reflexivity.
Raymond A. Ryan
6. The Chevet-Saphar Tensor Products
Abstract
In this chapter we begin a general study of tensor norms. Taking the projective and injective norms as our models, we formulate the appropriate definition of a tensor norm. We then investigate the Chevet-Saphar tensor norms, g p and d p . The dual spaces of the corresponding tensor products lead us to the definition of the p-summing operators. We conclude with the fundamental Grothendieck Inequality and some of its applications.
Raymond A. Ryan
7. Tensor Norms
Abstract
In this chapter, we study the basic properties of tensor norms. We begin with the dual norm and this leads naturally to the vital concept of accessibility, which can be thought of as an analogue for tensor norms of the approximation property for spaces. We then meet the various injective and projective norms that can be associated with a tensor norm. Next, we turn our attention to the identification of the duals of the Chevet—Saphar tensor norms in terms of the classes of p-integral operators. In the final section, we meet the Hilbertian tensor norm, which plays a central role in the theory. Grothendieck’s Inequality can now be interpreted as the statement that the Hilbertian tensor norm and the largest injective norm are equivalent. Two new classes of operators emerge: the Hilbertian and the 2-dominated operators. We conclude with Grothendieck’s classification of the natural tensor norms.
Raymond A. Ryan
8. Operator Ideals
Abstract
In this chapter we study the spaces of bilinear forms and operators that can be generated from a tensor norm. For each tensor norm α, we have the α-integral and the α-nuclear forms or operators. We introduce the concept of a Banach operator ideal and we develop just enough of the theory to explain the relationship between tensor norms and operator ideals. In particular, we see that the α-integral and α-nuclear classes constitute the maximal and minimal ideals respectively.
Raymond A. Ryan
Backmatter
Metadaten
Titel
Introduction to Tensor Products of Banach Spaces
verfasst von
Raymond A. Ryan
Copyright-Jahr
2002
Verlag
Springer London
Electronic ISBN
978-1-4471-3903-4
Print ISBN
978-1-84996-872-0
DOI
https://doi.org/10.1007/978-1-4471-3903-4