Search results for "Burrows-Wheeler-Transform"
showing 3 items of 3 documents
Computing the Original eBWT Faster, Simpler, and with Less Memory
2021
Mantaci et al. [TCS 2007] defined the \(\mathrm {eBWT}\) to extend the definition of the \(\mathrm {BWT}\) to a collection of strings. However, since this introduction, it has been used more generally to describe any \(\mathrm {BWT}\) of a collection of strings, and the fundamental property of the original definition (i.e., the independence from the input order) is frequently disregarded. In this paper, we propose a simple linear-time algorithm for the construction of the original \(\mathrm {eBWT}\), which does not require the preprocessing of Bannai et al. [CPM 2021]. As a byproduct, we obtain the first linear-time algorithm for computing the \(\mathrm {BWT}\) of a single string that uses …
Novel Results on the Number of Runs of the Burrows-Wheeler-Transform
2021
The Burrows-Wheeler-Transform (BWT), a reversible string transformation, is one of the fundamental components of many current data structures in string processing. It is central in data compression, as well as in efficient query algorithms for sequence data, such as webpages, genomic and other biological sequences, or indeed any textual data. The BWT lends itself well to compression because its number of equal-letter-runs (usually referred to as $r$) is often considerably lower than that of the original string; in particular, it is well suited for strings with many repeated factors. In fact, much attention has been paid to the $r$ parameter as measure of repetitiveness, especially to evalua…
r-Indexing the eBWT
2021
The extended Burrows Wheeler Transform (\(\mathrm {eBWT}\)) was introduced by Mantaci et al. [TCS 2007] to extend the definition of the \(\mathrm {BWT}\) to a collection of strings. In our prior work [SPIRE 2021], we give a linear-time algorithm for the \(\mathrm {eBWT}\) that preserves the fundamental property of the original definition (i.e., the independence from the input order). The algorithm combines a modification of the Suffix Array Induced Sorting (SAIS) algorithm [IEEE Trans Comput 2011] with Prefix Free Parsing [AMB 2019; JCB 2020]. In this paper, we show how this construction algorithm leads to r-indexing the \(\mathrm {eBWT}\), i.e., run-length encoded \(\mathrm {eBWT}\) and \(…