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A First Course in Functional Analysis

A First Course in Functional Analysis

Rabindranath Sen

(2013)

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Book Details

Abstract

This book provides the reader with a comprehensive introduction to functional analysis. Topics include normed linear and Hilbert spaces, the Hahn-Banach theorem, the closed graph theorem, the open mapping theorem, linear operator theory, the spectral theory, and a brief introduction to the Lebesgue measure. The book explains the motivation for the development of these theories, and applications that illustrate the theories in action. Applications in optimal control theory, variational problems, wavelet analysis and dynamical systems are also highlighted. ‘A First Course in Functional Analysis’ will serve as a ready reference to students not only of mathematics, but also of allied subjects in applied mathematics, physics, statistics and engineering.


Rabindranath Sen is a retired professor and former head of the Department of Applied Mathematics at the University of Calcutta.


‘A First Course in Functional Analysis: Theory and Applications’ provides a comprehensive introduction to functional analysis, beginning with the fundamentals and extending into theory and applications. The volume starts with an introduction to sets and metric spaces and the notions of convergence, completeness and compactness, and continues to a detailed treatment of normed linear spaces and Hilbert spaces. The reader is then introduced to linear operators and functionals, the Hahn-Banach theorem on linear bounded functionals, conjugate spaces and adjoint operators, and the space of linear bounded functionals. Further topics include the closed graph theorem, the open mapping theorem, linear operator theory including unbounded operators, spectral theory, and a brief introduction to the Lebesgue measure. The cornerstone of the book lies in the motivation for the development of these theories, and applications that illustrate the theories in action.

One of the many strengths of this book is its detailed discussion of the theory of compact linear operators and their relationship to singular operators. Applications in optimal control theory, variational problems, wavelet analysis and dynamical systems are highlighted.

This volume strikes an ideal balance between concision of mathematical exposition and offering complete explanatory materials and careful step-by-step instructions. It will serve as a ready reference not only for students of mathematics, but also students of physics, applied mathematics, statistics and engineering.One of the many strengths of the book is the detailed discussion of the theory of compact linear operators and their relationship to singular operators. Applications in optimal control theory, variational problems, wavelet analysis, and dynamical systems are highlighted.

This volume strikes the ideal balance between concision of mathematical exposition, and complete explanatory material accompanied by careful step-by-step instructions intended to serve as a ready reference not only for students of mathematics, but also students of physics, applied mathematics, statistics and engineering.

Table of Contents

Section Title Page Action Price
FRONT MATTER\r i
Half Title i
Title iii
Copyright\r iv
Preface vii
Contents xiii
Introduction xvii
CHAPTER 1 PRELIMINARIES xix
1.1 Set xix
1.2 Function, Mapping 3
1.3 Linear Space 4
1.4 Metric Spaces 10
1.5 Topological Spaces 43
1.6 Continuity, Compactness 50
CHAPTER 2 NORMED LINEAR SPACES 57
2.1 Definitions and Elementary Properties 57
2.2 Subspace, Closed Subspace 72
2.3 Finite Dimensional Normed Linear Spaces and Subspaces 75
2.4 Quotient Spaces 84
2.5 Completion of Normed Spaces\r 87
CHAPTER 3 HILBERT SPACE 90
3.1 Inner Product Space, Hilbert Space 90
3.2 Cauchy-Bunyakovsky-Schwartz (CBS) Inequality 93
3.3 Parallelogram Law 94
3.4 Orthogonality 99
3.5 Orthogonal Projection Theorem 101
3.6 Orthogonal Complements, Direct Sum 106
3.7 Orthogonal System 110
3.8 Complete Orthonormal System 121
3.9 Isomorphism between Separable Hilbert Spaces 127
CHAPTER 4 LINEAR OPERATORS 129
4.1 Definition: Linear Operator 129
4.2 Linear Operators in Normed Linear Spaces 135
4.3 Linear Functionals 146
4.4 The Space of Bounded Linear Operators 149
4.5 Uniform Boundedness Principle 153
4.6 Some Applications 158
4.7 Inverse Operators 163
4.8 Banach Space with a Basis 174
CHAPTER 5 LINEAR FUNCTIONALS 178
5.1 Hahn-Banach Theorem 178
5.2 Hahn-Banach Theorem for Complex Vector and Normed Linear Space 185
5.3 Application to Bounded Linear Functionals on C([a, b]) 193
5.4 The General Form of Linear Functionals in Certain Functional Spaces 199
5.5 The General Form of Linear Functionals in Hilbert Spaces 203
5.6 Conjugate Spaces and Adjoint Operators 205
CHAPTER 6 SPACE OF BOUNDED LINEAR FUNCTIONALS 220
6.1 Conjugates (Duals) and Transposes (Adjoints) 220
6.2 Conjugates (Duals) of Lp([a, b]) and C([a, b]) 227
6.3 Weak∗ and Weak Convergence 239
6.4 Reflexivity 251
6.5 Best Approximation in Reflexive Spaces 260
CHAPTER 7 CLOSED GRAPH THEOREM AND ITS CONSEQUENCES 266
7.1 Closed Graph Theorem 266
7.2 Open Mapping Theorem 271
7.3 Bounded Inverse Theorem 275
7.4 Applications of the Open Mapping Theorem 279
CHAPTER 8 COMPACT OPERATORS ON NORMED LINEAR SPACES 281
8.1 Compact Linear Operators 281
8.2 Spectrum of a Compact Operator 289
8.3 Fredholm Alternative 300
8.4 Approximate Solutions 310
CHAPTER 9 ELEMENTS OF SPECTRAL THEORY OF SELF-ADJOINT OPERATORS IN HILBERT SPACES 322
9.1 Adjoint Operators 322
9.2 Self-Adjoint Operators 324
9.3 Quadratic Form 326
9.4 Unitary Operators, Projection Operators 328
9.5 Positive Operators, Square Roots of a Positive Operator 333
9.6 Spectrum of Self-Adjoint Operators 340
9.7 Invariant Subspaces 344
9.8 Continuous Spectra and Point Spectra 346
CHAPTER 10 MEASURE AND INTEGRATION IN Lp SPACES 353
10.1 The Lebesgue Measure on R 353
10.2 Measurable and Simple Functions 359
10.3 Calculus with the Lebesgue Measure 366
10.4 The Fundamental Theorem for Riemann Integration 367
10.5 The Fundamental Theory for Lebesgue Integration 368
10.6 Lp Spaces and Completeness 369
10.7 Lp Convergence of Fourier Series 377
CHAPTER 11 UNBOUNDED LINEAR OPERATORS 380
11.1 Definition: An Unbounded Linear Operator 381
11.2 States of a Linear Operator 381
11.3 Definition: Strictly Singular Operators 385
11.4 Relationship between Singular and Compact Operators 388
11.5 Perturbation by Bounded Operators 389
11.6 Perturbation by Strictly Singular Operators 392
CHAPTER 12 THE HAHN-BANACH THEOREM AND OPTIMIZATION PROBLEMS 399
12.1 The Separation of a Convex Set 399
12.2 Minimum Norm Problem and the Duality Theory 401
12.3 Application to Chebyshev Approximation 405
12.4 Application to Optimal Control Problems 406
CHAPTER 13 VARIATIONAL PROBLEMS 409
13.1 Minimization of Functionals in a Normed Linear Space 409
13.2 Gateaux Derivative \r 409
13.3 Frechet Derivative\r 416
13.4 Equivalence of the Minimizing Problem for Solving Variational Inequality 419
13.5 Distributions 423
13.6 Sobolev Space 424
CHAPTER 14 THE WAVELET ANALYSIS 429
14.1 An Introduction to Wavelet Analysis 429
14.2 The Scalable Structure of Information 430
14.3 Algebra and Geometry of Wavelet Matrices 432
14.4 One-Dimensional Wavelet Systems 438
CHAPTER 15 DYNAMICAL SYSTEMS 442
15.1 A Dynamical System and Its Properties 442
15.2 Homeomorphism, Diffeomorphism, Riemannian Manifold 446
15.3 Stable Points, Periodic Points and Critical Points 448
15.4 Existence, Uniqueness and Topological Consequences 450
15.5 Bifurcation Points and Some Results 451
END MATTER\r 453
List of Symbols 453
Abbreviations 457
Bibliography 458
Index 462