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arXiv 2009.01699math.PRcs.NAmath.NA
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离散噪声最小奇异值的光滑分析

On the smoothed analysis of the smallest singular value with discrete noise

Vishesh Jain, Ashwin Sah, Mehtaab Sawhney

摘要:

令$A$是$n\times n$实矩阵,并且令$M$是$n\times n$随机矩阵,其条目是具有均值$0$和方差$1$的i.i.d亚高斯随机变量。本文对$A+M$的最小奇异值$s_n(A+M)$的研究做了两方面的贡献。(1)我们表明,对于所有的$ε\geq 0$,$$\mathbb{P}[s_n(A + M) \leq ε] = O(ε\sqrt{n}) + 2e^{-Ω(n)},$$只提供$A$有$Ω(n)$奇异值是$O(\sqrt{n})$。这扩展了Rudelson和Vershynin的一个著名结果,该结果要求$A$的所有奇异值都是$O(\sqrt{n})$。(2)证明了任何形式为$$\sup_{\|{A}\|\leq n^{C_1}}\mathbb{P}[s_n(A+M)\leq n^{-C_3}] \leq n^{-C_2}$$的界必有$C_3 = Ω(C_1 \sqrt{C_2})$ .这补充了Tao和Vu的结果,他们证明了这样一个与$C_3 = O(C_1C_2 + C_1 + 1)$的结合,并反驳了他们可能采取$C_3 = O(C_1 + C_2)$的猜测。

英文摘要:

Let $A$ be an $n\times n$ real matrix, and let $M$ be an $n\times n$ random matrix whose entries are i.i.d sub-Gaussian random variables with mean $0$ and variance $1$. We make two contributions to the study of $s_n(A+M)$, the smallest singular value of $A+M$. (1) We show that for all $ε\geq 0$, $$\mathbb{P}[s_n(A + M) \leq ε] = O(ε\sqrt{n}) + 2e^{-Ω(n)},$$ provided only that $A$ has $Ω(n)$ singular values which are $O(\sqrt{n})$. This extends a well-known result of Rudelson and Vershynin, which requires all singular values of $A$ to be $O(\sqrt{n})$. (2) We show that any bound of the form $$\sup_{\|{A}\|\leq n^{C_1}}\mathbb{P}[s_n(A+M)\leq n^{-C_3}] \leq n^{-C_2}$$ must have $C_3 = Ω(C_1 \sqrt{C_2})$. This complements a result of Tao and Vu, who proved such a bound with $C_3 = O(C_1C_2 + C_1 + 1)$, and counters their speculation of possibly taking $C_3 = O(C_1 + C_2)$.

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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