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Perturbations of Banach Frames and Atomic Decompositions
Author(s) -
Christensen Oel,
Heil Christopher
Publication year - 1997
Publication title -
mathematische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 50
eISSN - 1522-2616
pISSN - 0025-584X
DOI - 10.1002/mana.3211850104
Subject(s) - mathematics , banach space , hilbert space , perturbation (astronomy) , pure mathematics , basis (linear algebra) , wavelet , stability (learning theory) , stability theorem , atomic system , mathematical analysis , geometry , cauchy distribution , physics , quantum mechanics , artificial intelligence , machine learning , computer science
Banach frames and atomic decompositions are sequences that have basis‐like properties but which need not be bases. In particular, they allow elements of a Banach space to be written as linear combinations of the frame or atomic decomposition elements in a stable manner. In this paper we prove several functional — analytic properties of these decompositions, and show how these properties apply to Gabor and wavelet systems. We first prove that frames and atomic decompositions are stable under small perturbations. This is inspired by corresponding classical perturbation results for bases, including the Paley — Wiener basis stability criteria and the perturbation theorem el kato. We introduce new and weaker conditions which ensure the desired stability. We then prove quality properties of atomic decompositions and consider some consequences for Hilbert frames. Finally, we demonstrate how our results apply in the practical case of Gabor systems in weighted L 2 spaces. Such systems can form atomic decompositions for L 2 w (IR), but cannot form Hilbert frames but L 2 w (IR) unless the weight is trivial.