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arXiv math/0011232math.FAmath.APmath.PR
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$l_2^n$中线性算子的坐标限制

Coordinate restrictions of linear operators in $l_2^n$

R. Vershynin

摘要:

本文讨论了将$l_2^n$中的线性算子u限制在坐标子空间上以改善其性质的问题。我们讨论了如何通过一个随机坐标约束来降低u的范数,如何用一个具有小“坐标”秩的随机算子来近似u,如何找到u是同构的坐标子空间。第一个问题是Kashin和Tzafriri的一个抑制定理的概率扩展,第二个问题是Rudelson关于随机向量在各向同性位置的一个新结果,最后一个问题是Bourgain-Tzafriri可逆性原理的最近推广。主要的一点是,所有的结果都与n无关,而这种情况是由u的Hilbert-Schmidt范数控制的。作为应用,我们提供了一个几乎最优解,在调和分析的谐波密度的问题,并解决了重建问题的通信网络,提供数据的随机损失。

英文摘要:

This paper addresses the problem of improving properties of a linear operator u in $l_2^n$ by restricting it onto coordinate subspaces. We discuss how to reduce the norm of u by a random coordinate restriction, how to approximate u by a random operator with small "coordinate" rank, how to find coordinate subspaces where u is an isomorphism. The first problem in this list provides a probabilistic extension of a suppression theorem of Kashin and Tzafriri, the second one is a new look at a result of Rudelson on the random vectors in the isotropic position, the last one is the recent generalization of the Bourgain-Tzafriri's invertibility principle. The main point is that all the results are independent of n, the situation is instead controlled by the Hilbert-Schmidt norm of u. As an application, we provide an almost optimal solution to the problem of harmonic density in harmonic analysis, and a solution to the reconstruction problem for communication networks which deliver data with random losses.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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