Operator-Valued Measures, Dilations, and the Theory of Frames
Operator-Valued Measures, Dilations, and the Theory of Frames

Author: Deguang Han

Publisher: American Mathematical Soc.

Published: 2014-04-07

Total Pages: 98

ISBN-13: 0821891723

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The authors develop elements of a general dilation theory for operator-valued measures. Hilbert space operator-valued measures are closely related to bounded linear maps on abelian von Neumann algebras, and some of their results include new dilation results for bounded linear maps that are not necessarily completely bounded, and from domain algebras that are not necessarily abelian. In the non-cb case the dilation space often needs to be a Banach space. They give applications to both the discrete and the continuous frame theory. There are natural associations between the theory of frames (including continuous frames and framings), the theory of operator-valued measures on sigma-algebras of sets, and the theory of continuous linear maps between -algebras. In this connection frame theory itself is identified with the special case in which the domain algebra for the maps is an abelian von Neumann algebra and the map is normal (i.e. ultraweakly, or weakly, or w*) continuous.

Operator-valued Measures, Dilations, and the Theory of Frames
Operator-valued Measures, Dilations, and the Theory of Frames

Author: Deguang Han

Publisher:

Published: 2014

Total Pages: 0

ISBN-13: 9781470415297

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Our methods extend to some cases where the domain algebra need not be commutative, leading to new dilation results for maps of general von Neumann algebras. This paper was motivated by some recent results in frame theory and the observation that there is a close connection between the analysis of dual pairs of frames (both the discrete and the continuous theory) and the theory of operator-valued measures.

Operator Methods in Wavelets, Tilings, and Frames
Operator Methods in Wavelets, Tilings, and Frames

Author: Keri A. Kornelson

Publisher: American Mathematical Soc.

Published: 2014-10-20

Total Pages: 192

ISBN-13: 1470410400

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This volume contains the proceedings of the AMS Special Session on Harmonic Analysis of Frames, Wavelets, and Tilings, held April 13-14, 2013, in Boulder, Colorado. Frames were first introduced by Duffin and Schaeffer in 1952 in the context of nonharmonic Fourier series but have enjoyed widespread interest in recent years, particularly as a unifying concept. Indeed, mathematicians with backgrounds as diverse as classical and modern harmonic analysis, Banach space theory, operator algebras, and complex analysis have recently worked in frame theory. Frame theory appears in the context of wavelets, spectra and tilings, sampling theory, and more. The papers in this volume touch on a wide variety of topics, including: convex geometry, direct integral decompositions, Beurling density, operator-valued measures, and splines. These varied topics arise naturally in the study of frames in finite and infinite dimensions. In nearly all of the papers, techniques from operator theory serve as crucial tools to solving problems in frame theory. This volume will be of interest not only to researchers in frame theory but also to those in approximation theory, representation theory, functional analysis, and harmonic analysis.

Integral Representation
Integral Representation

Author: Walter Roth

Publisher: Walter de Gruyter GmbH & Co KG

Published: 2023-10-04

Total Pages: 266

ISBN-13: 3111315479

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This book presents a wide-ranging approach to operator-valued measures and integrals of both vector-valued and set-valued functions. It covers convergence theorems and an integral representation for linear operators on spaces of continuous vector-valued functions on a locally compact space. These are used to extend Choquet theory, which was originally formulated for linear functionals on spaces of real-valued functions, to operators of this type.

Dilations, Linear Matrix Inequalities, the Matrix Cube Problem and Beta Distributions
Dilations, Linear Matrix Inequalities, the Matrix Cube Problem and Beta Distributions

Author: J. William Helton

Publisher: American Mathematical Soc.

Published: 2019-02-21

Total Pages: 118

ISBN-13: 1470434555

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An operator C on a Hilbert space H dilates to an operator T on a Hilbert space K if there is an isometry V:H→K such that C=V∗TV. A main result of this paper is, for a positive integer d, the simultaneous dilation, up to a sharp factor ϑ(d), expressed as a ratio of Γ functions for d even, of all d×d symmetric matrices of operator norm at most one to a collection of commuting self-adjoint contraction operators on a Hilbert space.

Special Values of Automorphic Cohomology Classes
Special Values of Automorphic Cohomology Classes

Author: Mark Green

Publisher: American Mathematical Soc.

Published: 2014-08-12

Total Pages: 158

ISBN-13: 0821898574

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The authors study the complex geometry and coherent cohomology of nonclassical Mumford-Tate domains and their quotients by discrete groups. Their focus throughout is on the domains which occur as open -orbits in the flag varieties for and , regarded as classifying spaces for Hodge structures of weight three. In the context provided by these basic examples, the authors formulate and illustrate the general method by which correspondence spaces give rise to Penrose transforms between the cohomologies of distinct such orbits with coefficients in homogeneous line bundles.

A Geometric Theory for Hypergraph Matching
A Geometric Theory for Hypergraph Matching

Author: Peter Keevash

Publisher: American Mathematical Soc.

Published: 2014-12-20

Total Pages: 108

ISBN-13: 1470409658

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The authors develop a theory for the existence of perfect matchings in hypergraphs under quite general conditions. Informally speaking, the obstructions to perfect matchings are geometric, and are of two distinct types: `space barriers' from convex geometry, and `divisibility barriers' from arithmetic lattice-based constructions. To formulate precise results, they introduce the setting of simplicial complexes with minimum degree sequences, which is a generalisation of the usual minimum degree condition. They determine the essentially best possible minimum degree sequence for finding an almost perfect matching. Furthermore, their main result establishes the stability property: under the same degree assumption, if there is no perfect matching then there must be a space or divisibility barrier. This allows the use of the stability method in proving exact results. Besides recovering previous results, the authors apply our theory to the solution of two open problems on hypergraph packings: the minimum degree threshold for packing tetrahedra in -graphs, and Fischer's conjecture on a multipartite form of the Hajnal-Szemerédi Theorem. Here they prove the exact result for tetrahedra and the asymptotic result for Fischer's conjecture; since the exact result for the latter is technical they defer it to a subsequent paper.

A Homology Theory for Smale Spaces
A Homology Theory for Smale Spaces

Author: Ian F. Putnam

Publisher: American Mathematical Soc.

Published: 2014-09-29

Total Pages: 136

ISBN-13: 1470409097

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The author develops a homology theory for Smale spaces, which include the basics sets for an Axiom A diffeomorphism. It is based on two ingredients. The first is an improved version of Bowen's result that every such system is the image of a shift of finite type under a finite-to-one factor map. The second is Krieger's dimension group invariant for shifts of finite type. He proves a Lefschetz formula which relates the number of periodic points of the system for a given period to trace data from the action of the dynamics on the homology groups. The existence of such a theory was proposed by Bowen in the 1970s.

Local Entropy Theory of a Random Dynamical System
Local Entropy Theory of a Random Dynamical System

Author: Anthony H. Dooley

Publisher: American Mathematical Soc.

Published: 2014-12-20

Total Pages: 118

ISBN-13: 1470410559

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In this paper the authors extend the notion of a continuous bundle random dynamical system to the setting where the action of R or N is replaced by the action of an infinite countable discrete amenable group. Given such a system, and a monotone sub-additive invariant family of random continuous functions, they introduce the concept of local fiber topological pressure and establish an associated variational principle, relating it to measure-theoretic entropy. They also discuss some variants of this variational principle. The authors introduce both topological and measure-theoretic entropy tuples for continuous bundle random dynamical systems, and apply variational principles to obtain a relationship between these of entropy tuples. Finally, they give applications of these results to general topological dynamical systems, recovering and extending many recent results in local entropy theory.