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Greedy Approximation [Kõva köide]

(University of South Carolina)
Teised raamatud teemal:
Teised raamatud teemal:
"An introduction to two hot topics in numerical mathematics: learning theory and compressed sensing. This book possesses features of both a survey paper and a textbook. The majority of results are given with proofs. However,some important results with technically involved proofs are presented without proof. We included proofs of the most important and typical results; and we tried to include those proofs which demonstrate different ideas and are based on different techniques. In this sense the book has afeature of a survey - it tries to cover broad material. On the other hand, we limit ourselves to a systematic treatment of a specific topic rather than trying to give an overview of all related topics. In this sense the book is close to a textbook. Thereare many papers on theoretical and computational aspects of greedy approximation, learning theory and compressed sensing. We have chosen to cover the mathematical foundations of greedy approximation, learning theory and compressed sensing. The book is addressed to researchers working in numerical mathematics, analysis, functional analysis and statistics. It quickly takes the reader from classical results to the frontier of the unknown, but is written at the level of a graduate course and does not requirea broad background in order to understand the topics"--

"This first book on greedy approximation gives a systematic presentation of the fundamental results. It also contains an introduction to two hot topics in numerical mathematics: learning theory and compressed sensing. Nonlinear approximation is becoming increasingly important, especially since two types are frequently employed in applications: adaptive methods are used in PDE solvers, while m-term approximation is used in image/signal/data processing, as well as in the design of neural networks. The fundamental question of nonlinear approximation is how to devise good constructive methods (algorithms) and recent results have established that greedy type algorithms may be the solution. The author has drawn on his own teaching experience to write a book ideally suited to graduate courses. The reader does not require a broad background to understand the material. Important open problems are included to give students and professionals alike ideas for further research"--

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Arvustused

'The author is the leading expert on greedy approximation and this book offers a guided tour through the state of the art of the subject. Temlyakov's book is an excellent mathematical monograph and a valuable reference for researchers not only in approximation theory, but also in numerical mathematics, analysis, functional analysis, and statistics. The book is addressed mainly to researchers interested in greedy approximation and related areas. However, it is written at a level that is approachable for graduate students interested in the aforementioned areas, and it could be used for designing graduate courses in greedy approximation, learning theory and compressed sensing. As an added bonus, the author has included an extensive list of open problems in the area that can serve as inspiration for future research papers and dissertations.' Morten Nielsen, SIAM News

Muu info

Provides the theoretical foundations for algorithms widely used in numerical mathematics. Includes classical results, as well as the latest advances.
Preface ix
1 Greedy approximation with regard to bases
1(76)
1.1 Introduction
1(5)
1.2 Schauder bases in Banach spaces
6(9)
1.3 Greedy bases
15(18)
1.4 Quasi-greedy and almost greedy bases
33(6)
1.5 Weak Greedy Algorithms with respect to bases
39(4)
1.6 Thresholding and minimal systems
43(4)
1.7 Greedy approximation with respect to the trigonometric system
47(11)
1.8 Greedy-type bases; direct and inverse theorems
58(5)
1.9 Some further results
63(5)
1.10 Systems Lp-equivalent to the Haar basis
68(8)
1.11 Open problems
76(1)
2 Greedy approximation with respect to dictionaries: Hilbert spaces
77(66)
2.1 Introduction
77(7)
2.2 Convergence
84(5)
2.3 Rate of convergence
89(8)
2.4 Greedy algorithms for systems that are not dictionaries
97(4)
2.5 Greedy approximation with respect to λ-quasi-orthogonal dictionaries
101(10)
2.6 Lebesgue-type inequalities for greedy approximation
111(11)
2.7 Saturation property of greedy-type algorithms
122(13)
2.8 Some further remarks
135(6)
2.9 Open problems
141(2)
3 Entropy
143(40)
3.1 Introduction: definitions and some simple properties
143(1)
3.2 Finite dimensional spaces
144(7)
3.3 Trigonometric polynomials and volume estimates
151(14)
3.4 The function classes
165(3)
3.5 General inequalities
168(7)
3.6 Some further remarks
175(7)
3.7 Open problems
182(1)
4 Approximation in learning theory
183(94)
4.1 Introduction
183(6)
4.2 Some basic concepts of probability theory
189(17)
4.3 Improper function learning; upper estimates
206(29)
4.4 Proper function learning; upper estimates
235(18)
4.5 The lower estimates
253(17)
4.6 Application of greedy algorithms in learning theory
270(7)
5 Approximation in compressed sensing
277(57)
5.1 Introduction
277(6)
5.2 Equivalence of three approximation properties of the compressed sensing matrix
283(4)
5.3 Construction of a good matrix
287(7)
5.4 Dealing with noisy data
294(4)
5.5 First results on exact recovery of sparse signals; the Orthogonal Greedy Algorithm
298(7)
5.6 Exact recovery of sparse signals; the Subspace Pursuit Algorithm
305(9)
5.7 On the size of incoherent systems
314(13)
5.8 Restricted Isometry Property for random matrices
327(3)
5.9 Some further remarks
330(2)
5.10 Open problems
332(2)
6 Greedy approximation with respect to dictionaries: Banach spaces
334(71)
6.1 Introduction
334(6)
6.2 The Weak Chebyshev Greedy Algorithm
340(7)
6.3 Relaxation; co-convex approximation
347(3)
6.4 Free relaxation
350(4)
6.5 Fixed relaxation
354(5)
6.6 Thresholding algorithms
359(4)
6.7 Greedy expansions
363(15)
6.8 Relaxation; X-greedy algorithms
378(3)
6.9 Incoherent dictionaries and exact recovery
381(4)
6.10 Greedy algorithms with approximate evaluations and restricted search
385(5)
6.11 An application of greedy algorithms for the discrepancy estimates
390(14)
6.12 Open problems
404(1)
References 405(10)
Index 415
Vladimir Temlyakov is Carolina Distinguished Professor in the Department of Mathematics at the University of South Carolina.