DocumentCode :
610068
Title :
The Rightmost Equal-Cost Position Problem
Author :
Crochemore, M. ; Langiu, A. ; Mignosi, F.
Author_Institution :
King´s Coll. London, London, UK
fYear :
2013
fDate :
20-22 March 2013
Firstpage :
421
Lastpage :
430
Abstract :
LZ77-based compression schemes compress the input text by replacing factors in the text with an encoded reference to a previous occurrence formed by the couple (length, offset). For a given factor, the smallest is the offset, the smallest is the resulting compression ratio. This is optimally achieved by using the rightmost occurrence of a factor in the previous text. Given a cost function, for instance the minimum number of bits used to represent an integer, we define the Rightmost Equal-Cost Position (REP) problem as the problem of finding one of the occurrences of a factor whose cost is equal to the cost of the rightmost one. We present the Multi-Layer Suffix Tree data structure that, for a text of length n, at any time i, it provides REP(LPF) in constant time, where LPF is the longest previous factor, i.e. the greedy phrase, a reference to the list of REP({set of prefixes of LPF}) in constant time and REP(p) in time O(|p| log log n) for any given pattern p.
Keywords :
data compression; encoding; LPF; LZ77-based compression scheme; REP; cost function; encoded reference; greedy phrase; integer representation; multilayer suffix tree data structure; rightmost equal-cost position problem; Cost function; Data compression; Data structures; Dictionaries; Encoding; Indexes; Nonhomogeneous media; LZ77 compression; data compression; dictionary text compression; full text index; text compression;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Data Compression Conference (DCC), 2013
Conference_Location :
Snowbird, UT
ISSN :
1068-0314
Print_ISBN :
978-1-4673-6037-1
Type :
conf
DOI :
10.1109/DCC.2013.50
Filename :
6543078
Link To Document :
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