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arXiv 2202.01446cs.ITmath.IT
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噪声排序容量

Noisy Sorting Capacity

Ziao Wang, Nadim Ghaddar, Banghua Zhu, Lele Wang

AI总结:

针对固定未知错误概率下的成对比较排序问题,论文定义噪声排序容量,并结合插入排序与 Burnashev–Zigangirov 反馈编码算法给出定长和变长下界及容量上界。

摘要:

排序是利用成对比较对 $n$ 个元素进行排列的任务。众所周知,当比较结果在无噪声情况下被观测到时,$m=\Theta(n\log n)$ 次比较既是必要的也是充分的。本文研究当每次比较都以某个固定但未知的概率 $p$ 出错时的排序问题。与文献中旨在通过最小化成对比较次数 $m$ 来达到给定目标错误概率的常见方法不同,我们考虑具有期望查询次数 $\textsf{E}[M]$ 的随机算法,并致力于刻画最大排序速率 $\frac{n\log n}{\textsf{E}[M]}$,使得元素顺序能够在渐近意义下以趋于零的错误概率被估计出来。该最大速率被称为噪声排序容量。在本工作中,我们推导了噪声排序容量的上界和下界。两个下界——一个针对定长算法,另一个针对变长算法——通过将插入排序算法与著名的、用于带反馈信道编码的 Burnashev–Zigangirov 算法相结合而建立。与现有方法相比,所提出算法具有通用性,即它们不需要知道 $p$,同时保持严格为正的排序速率。此外,我们推导了噪声排序容量的一般上界,以及基于插入排序的排序算法所能达到的最大速率的上界。

英文摘要:

Sorting is the task of ordering $n$ elements using pairwise comparisons. It is well known that $m=Θ(n\log n)$ comparisons are both necessary and sufficient when the outcomes of the comparisons are observed with no noise. In this paper, we study the sorting problem when each comparison is incorrect with some fixed yet unknown probability $p$. Unlike the common approach in the literature which aims to minimize the number of pairwise comparisons $m$ to achieve a given desired error probability, we consider randomized algorithms with expected number of queries $\textsf{E}[M]$ and aim at characterizing the maximal sorting rate $\frac{n\log n}{\textsf{E}[M]}$ such that the ordering of the elements can be estimated with a vanishing error probability asymptotically. The maximal rate is referred to as the noisy sorting capacity. In this work, we derive upper and lower bounds on the noisy sorting capacity. The two lower bounds -- one for fixed-length algorithms and one for variable-length algorithms -- are established by combining the insertion sort algorithm with the well-known Burnashev--Zigangirov algorithm for channel coding with feedback. Compared with existing methods, the proposed algorithms are universal in the sense that they do not require the knowledge of $p$, while maintaining a strictly positive sorting rate. Moreover, we derive a general upper bound on the noisy sorting capacity, along with an upper bound on the maximal rate that can be achieved by sorting algorithms that are based on insertion sort.

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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