Title
Refining the r-index
Abstract
Gagie, Navarro and Prezza's r-index (SODA, 2018) promises to speed up DNA alignment and variation calling by allowing us to index entire genomic databases, provided certain obstacles can be overcome. In this paper we first strengthen and simplify Policriti and Prezza's Toehold Lemma (DCC '16; Algorithmica, 2017), which inspired the r-index and plays an important role in its implementation. We then show how to update the r-index efficiently after adding a new genome to the database, which is likely to be vital in practice. As a by-product of this result, we obtain an online version of Policriti and Prezza's algorithm for constructing the LZ77 parse from a run-length compressed Burrows-Wheeler Transform. Our experiments demonstrate the practicality of all three of these results. Finally, we show how to augment the r-index such that, given a new genome and fast random access to the database, we can quickly compute the matching statistics and maximal exact matches of the new genome with respect to the database.
Year
DOI
Venue
2020
10.1016/j.tcs.2019.08.005
Theoretical Computer Science
Keywords
DocType
Volume
Burrow-Wheeler transform,FM-index,r-index,Dynamic indexing,LZ77 parsing,Matching statistics
Journal
812
ISSN
Citations 
PageRank 
0304-3975
2
0.38
References 
Authors
0
3
Name
Order
Citations
PageRank
Hideo Bannai162079.87
Travis Gagie264363.61
Tomohiro I314822.06