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2013 | Book

Fractional Fields and Applications

Authors: Serge Cohen, Jacques Istas

Publisher: Springer Berlin Heidelberg

Book Series : Mathématiques et Applications

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About this book

This book focuses mainly on fractional Brownian fields and their extensions. It has been used to teach graduate students at Grenoble and Toulouse's Universities. It is as self-contained as possible and contains numerous exercises, with solutions in an appendix. After a foreword by Stéphane Jaffard, a long first chapter is devoted to classical results from stochastic fields and fractal analysis. A central notion throughout this book is self-similarity, which is dealt with in a second chapter with a particular emphasis on the celebrated Gaussian self-similar fields, called fractional Brownian fields after Mandelbrot and Van Ness's seminal paper. Fundamental properties of fractional Brownian fields are then stated and proved. The second central notion of this book is the so-called local asymptotic self-similarity (in short lass), which is a local version of self-similarity, defined in the third chapter. A lengthy study is devoted to lass fields with finite variance. Among these lass fields, we find both Gaussian fields and non-Gaussian fields, called Lévy fields. The Lévy fields can be viewed as bridges between fractional Brownian fields and stable self-similar fields. A further key issue concerns the identification of fractional parameters. This is the raison d'être of the statistics chapter, where generalized quadratic variations methods are mainly used for estimating fractional parameters. Last but not least, the simulation is addressed in the last chapter. Unlike the previous issues, the simulation of fractional fields is still an area of ongoing research. The algorithms presented in this chapter are efficient but do not claim to close the debate.

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
Fractals everywhere! This is the title of a bestseller, but it is also a reality: Fractals are really everywhere. What a change since the days of Charles Hermite declaring “I turn away with fright and horror of this terrible scourge of continuous functions without derivative”. Historically, the first fractals are the Cantor set, and the Weierstrass function, followed by the famous Brownian motion. In these seminal examples, there were already between the lines the basic properties self-similarity and roughness, we will find throughout this book. But, what does mean this word “fractal”? Or its more or less synonymous “fractional”? There are probably as many definitions as there are people who work on the subject. We follow two tracks in this book.
Serge Cohen, Jacques Istas
Chapter 2. Preliminaries
Abstract
In this chapter we have collected some results that will be used in the sequel of the book. We have divided these results in two parts. In the first one we recall some facts concerning stochastic processes. In the second part some results concerning fractal analysis are given.
Serge Cohen, Jacques Istas
Chapter 3. Self-Similarity
Abstract
Self-similarity is a major part of the mathematics. One can refer to [53] for a general reference. The self-similarity literature is quite confusing for beginners since the statement of very elementary facts may look very similar to deep theorems. On the one hand if you assume that you observe a self-similar phenomenon, then the self-similarity is an invariance property and you expect your phenomenon to be easier to study than general phenomena with no structure. On the other hand if you want to have a complete classification of self-similar fields then we can find in the literature a lot of counter-examples that prevent to draw even an heuristic picture of what is true for every self-similar fields. Following [138] a classical tool to simplify the study of the self-similarity in the stochastic case is to assume that the fields have stationary increments.
Serge Cohen, Jacques Istas
Chapter 4. Asymptotic Self-Similarity
Abstract
Self-similarity, as described in the previous chapter, is a global property, and as such, may be to rigid for some applications. Actually, in many situations the self-similarity parameter H is expected to change with time, and in spatial models, with position.
Serge Cohen, Jacques Istas
Chapter 5. Statistics
Abstract
In this chapter we would like to discuss the use of the models introduced in the previous chapters for Statistics. One of the major question is the estimation of the various parameters in those models. The common framework of this estimation is that we observe only one sample path of the field on a finite set of locations in a compact set. Most of the results will then be asymptotics, when the mesh of the grid of the locations where the fields are observed is decreasing to 0. In short we are doing fill-in statistics.
Serge Cohen, Jacques Istas
Chapter 6. Simulations
Abstract
The aim of this chapter is to give simulations of some of fractional fields introduced in the previous chapters. Our main concern here is algorithmic and heuristic : We would like to provide tools to probabilists and statisticians to show samples of fractional fields to practitioners so that they can decide if the proposed fractional models are useful for their own applications.
Serge Cohen, Jacques Istas
Backmatter
Metadata
Title
Fractional Fields and Applications
Authors
Serge Cohen
Jacques Istas
Copyright Year
2013
Publisher
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-36739-7
Print ISBN
978-3-642-36738-0
DOI
https://doi.org/10.1007/978-3-642-36739-7