A simpler analysis of burrows-wheeler based compression

Haim Kaplan*, Shir Landau, Elad Verbin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this paper we present a new technique for worst-case analysis of compression algorithms which are based on the Burrows-Wheeler Transform. We deal mainly with the algorithm purposed by Burrows and Wheeler in their first paper on the subject [6], called Bw0. This algorithm consists of the following three steps: 1) Compute the Burrows-Wheeler transform of the text, 2) Convert the transform into a sequence of integers using the move-to-front algorithm, 3) Encode the integers using Arithmetic code or any order-0 encoding (possibly with run-length encoding). We prove a strong upper bound on the worst-case compression ratio of this algorithm. This bound is significantly better than bounds known to date and is obtained via simple analytical techniques. Specifically, we show that for any input string s, and μ > 1, the length of the compressed string is bounded by μ · |s|Hk(s) + log(ζ(μ)) · |s| + 9k where Hk is the k-th order empirical entropy, gk is a constant depending only on k and on the size of the alphabet, and ζ(μ) = 1/1μ + 1/2μ +... is the standard zeta function. As part of the analysis we prove a result on the compressibility of integer sequences, which is of independent interest. Finally, we apply our techniques to prove a worst-case bound on the compression ratio of a compression algorithm based on the Burrows-Wheeler transform followed by distance coding, for which worst-case guarantees have never been given. We prove that the length of the compressed string is bounded by 1.7286 · |s|Hk(s) + gk. This bound is better than the bound we give for BW0.

Original languageEnglish
Title of host publicationCombinatorial Pattern Matching - 17th Annual Symposium, CPM 2006, Proceedings
PublisherSpringer Verlag
Pages282-293
Number of pages12
ISBN (Print)3540354557, 9783540354550
DOIs
StatePublished - 2006
Event17th Annual Symposium on Combinatorial Pattern Matching, CPM 2006 - Barcelona, Spain
Duration: 5 Jul 20067 Jul 2006

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4009 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference17th Annual Symposium on Combinatorial Pattern Matching, CPM 2006
Country/TerritorySpain
CityBarcelona
Period5/07/067/07/06

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