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arXiv 2005.07678cs.DS
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编辑近线性时间中的距离:它是一个常数

Edit Distance in Near-Linear Time: it's a Constant Factor

Alexandr Andoni, Negev Shekel Nosatzki

摘要:

我们提出了一个算法,用于近似的编辑距离两个字符串的长度$n$在时间$n^{1+\varepsilon}$到一个常数的因素,任何$\varepsilon>0$。我们的结果完成了最近的突破性论文[Chakraborty-Das-Goldenberg-Koucky-Saks,FOCS '18]中提出的研究方向,该论文显示了具有(强)次二次运行时间的第一个常数因子近似算法。[Koucky-Saks,STOC '20]和[Brakensiek-Rubinstein,STOC' 20]的最新结果显示了近线性时间算法,该算法在$n$中获得了近线性的加法近似(等效地,当编辑距离值接近$n$时,为常数因子近似)。相比之下,我们的算法获得了一个常数因子近似在近线性时间的任何输入字符串。与以前的算法相比,这主要是递归较小的子串,我们的算法逐渐平滑的本地贡献的编辑距离逐渐变大的子串。为了实现这一点,我们迭代地构造一个距离oracle数据结构,用于输入字符串的所有子串上的编辑距离的度量,长度为$i=0,1,\ldots,1/\varepsilon$的$n^{i\varepsilon}$。距离oracle在某种平均意义上近似于这些子字符串上的编辑距离,刚好足以估计整体编辑距离。

英文摘要:

We present an algorithm for approximating the edit distance between two strings of length $n$ in time $n^{1+\varepsilon}$ up to a constant factor, for any $\varepsilon>0$. Our result completes a research direction set forth in the recent breakthrough paper [Chakraborty-Das-Goldenberg-Koucky-Saks, FOCS'18], which showed the first constant-factor approximation algorithm with a (strongly) sub-quadratic running time. The recent results of [Koucky-Saks, STOC'20] and [Brakensiek-Rubinstein, STOC'20] have shown near-linear time algorithms that obtain an additive approximation, near-linear in $n$ (equivalently, constant-factor approximation when the edit distance value is close to $n$). In contrast, our algorithm obtains a constant-factor approximation in near-linear time for any input strings. In contrast to prior algorithms, which are mostly recursing over smaller substrings, our algorithm gradually smoothes out the local contribution to the edit distance over progressively larger substrings. To accomplish this, we iteratively construct a distance oracle data structure for the metric of edit distance on all substrings of input strings, of length $n^{i\varepsilon}$ for $i=0,1,\ldots,1/\varepsilon$. The distance oracle approximates the edit distance over these substrings in a certain average sense, just enough to estimate the overall edit distance.

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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