Abstract
Given s G R and 1 < p, q < oo the modulation space Mp g (R m ) can be described as follows, using the Gauss-function go,go(x) '•= exp(-x 2 )for the modulation operator.Among these spaces one has the classical potential spaces £2( R m) _ jv/| 2 (R m ) and the remarkable Segal algebra 5 0 (R m ) = Mf^R™).It is the aim of this paper to show that for these spaces an atomic characterization similar to known characterization of Besov spaces can be given (with dilation being replaced by modulation).Our main theorem is the following: Given s G R and some So # 0, go G Mj*j(R m ) (e.g., g G 5(R m ) or g G L 1 with compactly supported Fourier transform) one has:THEOREM .There exist ao > 0 and ßo > 0 such that, for a < a 0 and ß < ßo, there exists C = C(a,ß) > 0 with the following property: f e M^q(R m ) if and only iff = Yin,k a n,kMß n L ak go, for some double sequence of coefficients satisfying [E (El 0 ».*!")*^1 + Wr] 1/9 < c||/|M p yR m )||. n kThe convergence is in the sense of tempered distributions, and in the norm sense for p,q < oo.
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Publication Info
- Year
- 1989
- Type
- article
- Volume
- 19
- Issue
- 1
- Citations
- 141
- Access
- Closed
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Identifiers
- DOI
- 10.1216/rmj-1989-19-1-113