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Documents authored by Masillo, Francesco


Document
Matching Statistics Speed up BWT Construction

Authors: Francesco Masillo

Published in: LIPIcs, Volume 274, 31st Annual European Symposium on Algorithms (ESA 2023)


Abstract
Due to the exponential growth of genomic data, constructing dedicated data structures has become the principal bottleneck in common bioinformatics applications. In particular, the Burrows-Wheeler Transform (BWT) is the basis of some of the most popular self-indexes for genomic data, due to its known favourable behaviour on repetitive data. Some tools that exploit the intrinsic repetitiveness of biological data have risen in popularity, due to their speed and low space consumption. We introduce a new algorithm for computing the BWT, which takes advantage of the redundancy of the data through a compressed version of matching statistics, the CMS of [Lipták et al., WABI 2022]. We show that it suffices to sort a small subset of suffixes, lowering both computation time and space. Our result is due to a new insight which links the so-called insert-heads of [Lipták et al., WABI 2022] to the well-known run boundaries of the BWT. We give two implementations of our algorithm, called CMS-BWT, both competitive in our experimental validation on highly repetitive real-life datasets. In most cases, they outperform other tools w.r.t. running time, trading off a higher memory footprint, which, however, is still considerably smaller than the total size of the input data.

Cite as

Francesco Masillo. Matching Statistics Speed up BWT Construction. In 31st Annual European Symposium on Algorithms (ESA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 274, pp. 83:1-83:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{masillo:LIPIcs.ESA.2023.83,
  author =	{Masillo, Francesco},
  title =	{{Matching Statistics Speed up BWT Construction}},
  booktitle =	{31st Annual European Symposium on Algorithms (ESA 2023)},
  pages =	{83:1--83:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-295-2},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{274},
  editor =	{G{\o}rtz, Inge Li and Farach-Colton, Martin and Puglisi, Simon J. and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2023.83},
  URN =		{urn:nbn:de:0030-drops-187360},
  doi =		{10.4230/LIPIcs.ESA.2023.83},
  annote =	{Keywords: Burrows-Wheeler Transform, matching statistics, string collections, compressed representation, data structures, efficient algorithms}
}
Document
Suffix Sorting via Matching Statistics

Authors: Zsuzsanna Lipták, Francesco Masillo, and Simon J. Puglisi

Published in: LIPIcs, Volume 242, 22nd International Workshop on Algorithms in Bioinformatics (WABI 2022)


Abstract
We introduce a new algorithm for constructing the generalized suffix array of a collection of highly similar strings. As a first step, we construct a compressed representation of the matching statistics of the collection with respect to a reference string. We then use this data structure to distribute suffixes into a partial order, and subsequently to speed up suffix comparisons to complete the generalized suffix array. Our experimental evidence with a prototype implementation (a tool we call sacamats) shows that on string collections with highly similar strings we can construct the suffix array in time competitive with or faster than the fastest available methods. Along the way, we describe a heuristic for fast computation of the matching statistics of two strings, which may be of independent interest.

Cite as

Zsuzsanna Lipták, Francesco Masillo, and Simon J. Puglisi. Suffix Sorting via Matching Statistics. In 22nd International Workshop on Algorithms in Bioinformatics (WABI 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 242, pp. 20:1-20:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{liptak_et_al:LIPIcs.WABI.2022.20,
  author =	{Lipt\'{a}k, Zsuzsanna and Masillo, Francesco and Puglisi, Simon J.},
  title =	{{Suffix Sorting via Matching Statistics}},
  booktitle =	{22nd International Workshop on Algorithms in Bioinformatics (WABI 2022)},
  pages =	{20:1--20:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-243-3},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{242},
  editor =	{Boucher, Christina and Rahmann, Sven},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.WABI.2022.20},
  URN =		{urn:nbn:de:0030-drops-170545},
  doi =		{10.4230/LIPIcs.WABI.2022.20},
  annote =	{Keywords: Generalized suffix array, matching statistics, string collections, compressed representation, data structures, efficient algorithms}
}
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