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arXiv 0705.0274math.STstat.TH
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反问题估计的Needlet算法

Needlet algorithms for estimation in inverse problems

Gérard Kerkyacharian, Pencho Petrushev, Dominique Picard, Thomas Willer

摘要:

我们提供了一种新的算法,它结合了传统的SVD反演与适当的阈值技术在一个良好的选择新的基础上的反问题的治疗。我们的目标是设计一个反演程序,它具有本地化和多尺度分析的小波表示的优点,而不会失去SVD分解的稳定性和可计算性。为此,我们利用本地化的框架(称为“针”)的SVD基础上建立的建设。我们考虑两种不同的情况:“小波”的情况下,needlets被假定为表现类似于真正的小波,和“雅可比型”的情况下,我们假设的框架的属性真正取决于手头的SVD基础(因此对运营商)。为了说明每种情况下,我们分别应用估计算法的反卷积问题和Wicksell问题。在后一种情况下,当SVD基是雅可比多项式基时,我们证明了我们的方案能够达到在$L_2$情况下最优的收敛速度,我们得到了其他新的$L_p$范数的有趣的收敛速度(据我们所知)在文献中,仿真结果表明NEED-D估计器在几乎所有情况下都优于其他标准算法。

英文摘要:

We provide a new algorithm for the treatment of inverse problems which combines the traditional SVD inversion with an appropriate thresholding technique in a well chosen new basis. Our goal is to devise an inversion procedure which has the advantages of localization and multiscale analysis of wavelet representations without losing the stability and computability of the SVD decompositions. To this end we utilize the construction of localized frames (termed "needlets") built upon the SVD bases. We consider two different situations: the "wavelet" scenario, where the needlets are assumed to behave similarly to true wavelets, and the "Jacobi-type" scenario, where we assume that the properties of the frame truly depend on the SVD basis at hand (hence on the operator). To illustrate each situation, we apply the estimation algorithm respectively to the deconvolution problem and to the Wicksell problem. In the latter case, where the SVD basis is a Jacobi polynomial basis, we show that our scheme is capable of achieving rates of convergence which are optimal in the $L_2$ case, we obtain interesting rates of convergence for other $L_p$ norms which are new (to the best of our knowledge) in the literature, and we also give a simulation study showing that the NEED-D estimator outperforms other standard algorithms in almost all situations.

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