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arXiv 2404.08085cs.DS
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矩阵乘法归约

Matrix Multiplication Reductions

Ashish Gola, Igor Shinkar, Harsimran Singh

AI总结:

本文研究有限域上矩阵乘法的最坏情况到平均情况归约,分别给出高一致度双边错误、$\mathbb{F}_2$域低一致度单边错误场景下的归约方法,可将平均情况算法转化为高效的最坏情况算法。

摘要:

本文研究有限域上矩阵乘法问题的最坏情况到平均情况的归约。假设我们存在一种高效的平均情况算法,给定两个随机矩阵$A,B$,该算法输出的矩阵与其乘积$A \cdot B$具有非平凡的相关性。我们能否将其转化为一种最坏情况算法,在运行时间无显著开销的前提下,对所有输入都能输出正确结果?本文给出了该方向的两个研究结果。\n (1)高一致度场景下的双边错误:我们首先简要评述针对高一致度算法的归约——这类算法在大部分(例如$>0.9$)元素上与正确输出一致,并证明标准的线性自校正方法可将此类算法转化为适用于最坏情况的算法。\n (2)低一致度场景下的单边错误:针对具有单边错误的平均情况算法,我们证明在$\mathbb{F}_2$域上存在一种归约:该归约接收一个时间复杂度为$O(T)$的平均情况算法(该算法给定随机输入$A,B$时,输出矩阵与$A \cdot B$至少在51%的元素上一致,即仅比平凡算法有微弱优势),并将其转化为时间复杂度为$\widetilde{O}(T)$的最坏情况算法,该算法能以高概率对所有输入输出正确结果。

英文摘要:

In this paper we study a worst case to average case reduction for the problem of matrix multiplication over finite fields. Suppose we have an efficient average case algorithm, that given two random matrices $A,B$ outputs a matrix that has a non-trivial correlation with their product $A \cdot B$. Can we transform it into a worst case algorithm, that outputs the correct answer for all inputs without incurring a significant overhead in the running time? We present two results in this direction. (1) Two-sided error in the high agreement regime: We begin with a brief remark about a reduction for high agreement algorithms, i.e., an algorithm which agrees with the correct output on a large (say $>0.9$) fraction of entries, and show that the standard self-correction of linearity allows us to transform such algorithms into algorithms that work in worst case. (2) One-sided error in the low agreement regime: Focusing on average case algorithms with one-sided error, we show that over $\mathbb{F}_2$ there is a reduction that gets an $O(T)$ time average case algorithm that given a random input $A,B$ outputs a matrix that agrees with $A \cdot B$ on at least $51\%$ of the entries (i.e., has only a slight advantage over the trivial algorithm), and transforms it into an $\widetilde{O}(T)$ time worst case algorithm, that outputs the correct answer for all inputs with high probability.

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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