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arXiv 1707.06374cs.DS
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关于保证性能的重复收款的文档列表

Document Listing on Repetitive Collections with Guaranteed Performance

Gonzalo Navarro

摘要:

我们考虑在字符串集合上列出文档,即查找给定模式出现在哪些字符串中。特别是,我们专注于重复的集合:一个集合的大小$N$在字母表$[1,σ]$是由$n$大小的字符串的$D$副本,$s$编辑应用于范围内的副本。我们引入了第一个文档列表索引,其大小为$\tilde{O}(n+s)$,确切地说是$O((n\logσ+s\log^2 N)\log D)$位,并且具有有用的最坏情况时间保证:给定长度为$m$的模式,对于任何恒定的$ε>0$,索引报告$\ndoc>0$字符串在时间上出现的位置$O(m\log^{1+ε} N \cdot \ndoc)$(并且如果$\ndoc=0$,则在时间上告诉$O(m\log N)$)。我们的技术是增加一个范围数据结构,这是常用的基于语法的索引,所以,而不是检索所有的模式出现,它计算有用的摘要。我们的想法有独立的兴趣:我们引入了第一个基于语法的索引,在文本$T[1,N]$与语法的大小$r$,使用$O(r\log N)$位和计数的出现次数的模式$P[1,m]$在时间$O(m^2 + m\log^{2+ε} r)$,任何常数$ε>0$。我们还使用$O(z\log(N/z)\log N)$位给出了第一个索引,其中$T$由Lempel-Ziv解析为$z$短语,计算时间上出现的次数$O(m\log^{2+ε} N)$。

英文摘要:

We consider document listing on string collections, that is, finding in which strings a given pattern appears. In particular, we focus on repetitive collections: a collection of size $N$ over alphabet $[1,σ]$ is composed of $D$ copies of a string of size $n$, and $s$ edits are applied on ranges of copies. We introduce the first document listing index with size $\tilde{O}(n+s)$, precisely $O((n\logσ+s\log^2 N)\log D)$ bits, and with useful worst-case time guarantees: Given a pattern of length $m$, the index reports the $\ndoc>0$ strings where it appears in time $O(m\log^{1+ε} N \cdot \ndoc)$, for any constant $ε>0$ (and tells in time $O(m\log N)$ if $\ndoc=0$). Our technique is to augment a range data structure that is commonly used on grammar-based indexes, so that instead of retrieving all the pattern occurrences, it computes useful summaries on them. We show that the idea has independent interest: we introduce the first grammar-based index that, on a text $T[1,N]$ with a grammar of size $r$, uses $O(r\log N)$ bits and counts the number of occurrences of a pattern $P[1,m]$ in time $O(m^2 + m\log^{2+ε} r)$, for any constant $ε>0$. We also give the first index using $O(z\log(N/z)\log N)$ bits, where $T$ is parsed by Lempel-Ziv into $z$ phrases, counting occurrences in time $O(m\log^{2+ε} N)$.

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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