Title

Analysis Of Orthogonality And Of Orbits In Affine Iterated Function Systems

Keywords

Affine fractal; Attractor; Fourier series; Hilbert space; Spectral measure; Spectrum

Abstract

We introduce a duality for affine iterated function systems (AIFS) which is naturally motivated by group duality in the context of traditional harmonic analysis. Our affine systems yield fractals defined by iteration of contractive affine mappings. We build a duality for such systems by scaling in two directions: fractals in the small by contractive iterations, and fractals in the large by recursion involving iteration of an expansive matrix. By a fractal in the small we mean a compact attractor X supporting Hutchinson's canonical measure μ, and we ask when μ is a spectral measure, i.e., when the Hilbert space L2(μ) has an orthonormal basis (ONB) of exponentials {eΛ |Λ ∈ A}. We further introduce a Fourier duality using a matched pair of such affine systems. Using next certain extreme cycles, and positive powers of the expansive matrix we build fractals in the large which are modeled on lacunary Fourier series and which serve as spectra for X. Our two main results offer simple geometric conditions allowing us to decide when the fractal in the large is a spectrum for X. Our results in turn are illustrated with concrete Sierpinski like fractals in dimensions 2 and 3. © Springer-Verlag 2007.

Publication Date

8-1-2007

Publication Title

Mathematische Zeitschrift

Volume

256

Issue

4

Number of Pages

801-823

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1007/s00209-007-0104-9

Socpus ID

34249054752 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/34249054752

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