Weighted Approximation with Varying Weight

Weighted Approximation with Varying Weight
Author: Vilmos Totik
Publisher: Springer
Total Pages: 119
Release: 2006-11-15
Genre: Mathematics
ISBN: 3540483233

A new construction is given for approximating a logarithmic potential by a discrete one. This yields a new approach to approximation with weighted polynomials of the form w"n"(" "= uppercase)P"n"(" "= uppercase). The new technique settles several open problems, and it leads to a simple proof for the strong asymptotics on some L p(uppercase) extremal problems on the real line with exponential weights, which, for the case p=2, are equivalent to power- type asymptotics for the leading coefficients of the corresponding orthogonal polynomials. The method is also modified toyield (in a sense) uniformly good approximation on the whole support. This allows one to deduce strong asymptotics in some L p(uppercase) extremal problems with varying weights. Applications are given, relating to fast decreasing polynomials, asymptotic behavior of orthogonal polynomials and multipoint Pade approximation. The approach is potential-theoretic, but the text is self-contained.

Existence Families, Functional Calculi and Evolution Equations

Existence Families, Functional Calculi and Evolution Equations
Author: Ralph DeLaubenfels
Publisher: Springer
Total Pages: 260
Release: 1994-03-28
Genre: Mathematics
ISBN: 9783540577034

This book presents an operator-theoretic approach to ill-posed evolution equations. It presents the basic theory, and the more surprising examples, of generalizations of strongly continuous semigroups known as 'existent families' and 'regularized semigroups'. These families of operators may be used either to produce all initial data for which a solution in the original space exists, or to construct a maximal subspace on which the problem is well-posed. Regularized semigroups are also used to construct functional, or operational, calculi for unbounded operators. The book takes an intuitive and constructive approach by emphasizing the interaction between functional calculus constructions and evolution equations. One thinks of a semigroup generated by A as etA and thinks of a regularized semigroup generated by A as etA g(A), producing solutions of the abstract Cauchy problem for initial data in the image of g(A). Material that is scattered throughout numerous papers is brought together and presented in a fresh, organized way, together with a great deal of new material.

Bounds and Asymptotics for Orthogonal Polynomials for Varying Weights

Bounds and Asymptotics for Orthogonal Polynomials for Varying Weights
Author: Eli Levin
Publisher: Springer
Total Pages: 168
Release: 2018-02-13
Genre: Mathematics
ISBN: 3319729470

This book establishes bounds and asymptotics under almost minimal conditions on the varying weights, and applies them to universality limits and entropy integrals. Orthogonal polynomials associated with varying weights play a key role in analyzing random matrices and other topics. This book will be of use to a wide community of mathematicians, physicists, and statisticians dealing with techniques of potential theory, orthogonal polynomials, approximation theory, as well as random matrices.

Introduction To The Theory Of Weighted Polynomial Approximation

Introduction To The Theory Of Weighted Polynomial Approximation
Author: H N Mhaskar
Publisher: World Scientific
Total Pages: 398
Release: 1997-01-04
Genre: Mathematics
ISBN: 9814518050

In this book, we have attempted to explain a variety of different techniques and ideas which have contributed to this subject in its course of successive refinements during the last 25 years. There are other books and surveys reviewing the ideas from the perspective of either potential theory or orthogonal polynomials. The main thrust of this book is to introduce the subject from an approximation theory point of view. Thus, the main motivation is to study analogues of results from classical trigonometric approximation theory, introducing other ideas as needed. It is not our objective to survey the most recent results, but merely to introduce to the readers the thought processes and ideas as they are developed.This book is intended to be self-contained, although the reader is expected to be familiar with rudimentary real and complex analysis. It will also help to have studied elementary trigonometric approximation theory, and have some exposure to orthogonal polynomials.

Author:
Publisher: Springer Nature
Total Pages: 598
Release:
Genre:
ISBN: 3031651332

Potential Theory on Infinite Networks

Potential Theory on Infinite Networks
Author: Paolo M. Soardi
Publisher: Springer
Total Pages: 199
Release: 2006-11-15
Genre: Mathematics
ISBN: 3540487980

The aim of the book is to give a unified approach to new developments in discrete potential theory and infinite network theory. The author confines himself to the finite energy case, but this does not result in loss of complexity. On the contrary, the functional analytic machinery may be used in analogy with potential theory on Riemann manifolds. The book is intended for researchers with interdisciplinary interests in one of the following fields: Markov chains, combinatorial graph theory, network theory, Dirichlet spaces, potential theory, abstract harmonic analysis, theory of boundaries.

On Artin's Conjecture for Odd 2-dimensional Representations

On Artin's Conjecture for Odd 2-dimensional Representations
Author: Gerhard Frey
Publisher: Springer
Total Pages: 160
Release: 2006-11-15
Genre: Mathematics
ISBN: 354048681X

The main topic of the volume is to develop efficient algorithms by which one can verify Artin's conjecture for odd two-dimensional representations in a fairly wide range. To do this, one has to determine the number of all representations with given Artin conductor and determinant and to compute the dimension of a corresponding space of cusp forms of weight 1 which is done by exploiting the explicit knowledge of the operation of Hecke operators on modular symbols. It is hoped that the algorithms developed in the volume can be of use for many other problems related to modular forms.

Phase Transitions and Hysteresis

Phase Transitions and Hysteresis
Author: Augusto Visintin
Publisher: Springer
Total Pages: 301
Release: 2006-11-15
Genre: Mathematics
ISBN: 354048678X

1) Phase Transitions, represented by generalizations of the classical Stefan problem. This is studied by Kenmochi and Rodrigues by means of variational techniques. 2) Hysteresis Phenomena. Some alloys exhibit shape memory effects, corresponding to a stress-strain relation which strongly depends on temperature; mathematical physical aspects are treated in Müller's paper. In a general framework, hysteresis can be described by means of hysteresis operators in Banach spaces of time dependent functions; their properties are studied by Brokate. 3) Numerical analysis. Several models of the phenomena above can be formulated in terms of nonlinear parabolic equations. Here Verdi deals with the most updated approximation techniques.

Finsler Metrics - A Global Approach

Finsler Metrics - A Global Approach
Author: Marco Abate
Publisher: Springer
Total Pages: 185
Release: 2006-11-15
Genre: Mathematics
ISBN: 354048812X

Complex Finsler metrics appear naturally in complex analysis. To develop new tools in this area, the book provides a graduate-level introduction to differential geometry of complex Finsler metrics. After reviewing real Finsler geometry stressing global results, complex Finsler geometry is presented introducing connections, Kählerianity, geodesics, curvature. Finally global geometry and complex Monge-Ampère equations are discussed for Finsler manifolds with constant holomorphic curvature, which are important in geometric function theory. Following E. Cartan, S.S. Chern and S. Kobayashi, the global approach carries the full strength of hermitian geometry of vector bundles avoiding cumbersome computations, and thus fosters applications in other fields.

Difference Spaces and Invariant Linear Forms

Difference Spaces and Invariant Linear Forms
Author: Rodney Nillsen
Publisher: Springer
Total Pages: 198
Release: 2006-11-15
Genre: Mathematics
ISBN: 3540486526

Difference spaces arise by taking sums of finite or fractional differences. Linear forms which vanish identically on such a space are invariant in a corresponding sense. The difference spaces of L2 (Rn) are Hilbert spaces whose functions are characterized by the behaviour of their Fourier transforms near, e.g., the origin. One aim is to establish connections between these spaces and differential operators, singular integral operators and wavelets. Another aim is to discuss aspects of these ideas which emphasise invariant linear forms on locally compact groups. The work primarily presents new results, but does so from a clear, accessible and unified viewpoint, which emphasises connections with related work.