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	LZ77 and LZ78 (algorithms) - Wikipedia, the free encyclopedia
		LZ77 and LZ78 are the names for the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978.
		Though initially popular, the popularity of LZ78 later dampened, possibly because for the first few decades after it was introduced, parts of LZ78 were patent encumbered in the United States.
		The most popular form of LZ78 compression was the LZW algorithm, a modification of the LZ78 algorithm made by Terry Welch.
	en.wikipedia.org /wiki/LZ78 (1042 words)

	Lossless Data Compression: LZ78
		Under LZ78, the dictionary is a potentially unlimited collection of previously seen phrases.
		LZ78-based schemes work by entering phrases into a ‘dictionary’ and then, when a repeat occurrence of that particular phrase is found, outputting a token that consists of the dictionary index instead of the phrase, as well as a single character that follows that phrase.
		Since 256 cannot be represent by the standard 8-bit byte, this would require 9 bits – nevertheless, it is still a great improvement on the standard 40-bit ASCII encoding.
	cse.stanford.edu /class/sophomore-college/projects-00/data-compression/lossless/lz78/concept.htm (362 words)

	[No title] (Site not responding. Last check: 2007-10-10)
		In LZ78 a parsing tree is built by the "compressor", which will also be regenerated by the "decompressor" at the time of decoding.
		LZ78 was improved upon in 1984 by a man named Welch, thus giving us the LZW Algorithm.
		LZ78 was the algorithm that was used in Unix Compress, which is still available on many systems.
	www.eecis.udel.edu /~staiano/ELEG867/lz78.html (299 words)

	LZ78 (Site not responding. Last check: 2007-10-10)
		LZ77 and LZ78 are the names for the two lossless data compression algorithms published inpapers by Abraham Lempel and Jacob Ziv in 1977 and 1978.
		LZ77 isthe "sliding window" compression algorithm, which was later shown to be equivalent to the explicit dictionary technique firstgiven in LZ78.
		LZ78 never became as popular as LZ77 because for the first few decades after it was introduced, LZ78 was somewhat of a patent minefield in the UnitedStates, while LZ77 is not patented.
	www.therfcc.org /lz78-195096.html (358 words)

	Class notes CS251B -- Winter 1997
		The highly innovative LZ77 and LZ78 methods, although usually referred to as the singular Lempel-Ziv (LZ) or Ziv-Lempel method, are in fact considerably different.
		In both cases, encoding proceeds "on the fly," so that as symbols are read in, more and more phrases are stored (in that respect, the LZ compression techniques are a bit like a suffix trie).
		Lempel and Ziv's compression techniques of '77 and '78 gave rise to a series of variants which form part of the LZ family.
	www.cs.mcgill.ca /~cs251/OldCourses/1997/topic23 (1472 words)

	[No title] (Site not responding. Last check: 2007-10-10)
		Prediction Using Incremental Parsing — The LZ78 Algorithm An important result that is derived in (Feder, Merhav and Gutman 1992) is that a sub-class of the class of FS predictors, the class of Markov Predictors, performs asymptotically as well as any FSM.
		The LZ78 data compression algorithm as suggested by Lempel and Ziv (Ziv and Lempel 1978), is an incremental parsing algorithm that introduces exactly such a method for gradually changing the Markov order at the appropriate rate.
		LZ78 is a dictionary-based text compression algorithm that performs incremental parsing of an input sequence.
	mavhome.uta.edu /publications/karthikflairs03.doc (2810 words)

	LZ78 (Site not responding. Last check: 2007-10-10)
		Since the string did have a match in the dictionary until the last character was read in, the current string is defined as that last match with one new character added on.
		LZ78 takes this process one step further by adding this new phrase, consisting of the dictionary match and the new character, to the dictionary.
		The output of LZ78 algorithm will be in the form , where i is the index corresponding to the dictionary entry that has the longest match to the input and c the codeword of the character that broke up the match.
	www.msci.memphis.edu /~giri/7717/s99/compression/lz78.html (292 words)

	Hacking Data Compression - Lesson 8
		LZ78 outputs two symbols each time, the longest matching phrase and the first character that didn't match.
		With LZ78, we would've output the 0 followed by the second 'a'.
		There are LZ78 variants which actually combine the last two phrases to form new phrases; this causes the phrase table to expand much more quickly.
	www.fadden.com /techmisc/hdc/lesson08.htm (3158 words)

	Overview (Site not responding. Last check: 2007-10-10)
		LZ78 is part of the family of LZ dictionary algorithms, which work by caching in on repetition of small lexical units and larger phrases in data files.
		LZ78 was invented by Lempel and Ziv in 1978.
		A significant improvement to this algorithm was implemented by Welch in 1984 and patented by Unisys.
	www2.hawaii.edu /~luoma/Overview.html (190 words)

	LZ77 compression - Definition of LZ77 compression by Webster's Online Dictionary (Site not responding. Last check: 2007-10-10)
		The sliding window approach automatically creates the LRU effect which must be done explicitly in LZ78 schemes.
		An algorithm was developed which combines the ideas behind LZ77 and LZ78 to produce a hybrid called LZFG.
		LZFG uses the standard sliding window, but stores the data in a modified trie data structure and produces as output the position of the text in the trie.
	www.webster-dictionary.org /definition/LZ77%20compression (401 words)

	Towards Analytical Information Theory: Recent Results on Lempel-Ziv Data Compression Schemes
		Each internal node of the tree is associated with such a segment seen in the past and insertion takes place at an external node, which corresponds to extending a previously encountered segment.
		Consider an execution of the LZ78 algorithm when n characters of the text have been scanned, assuming that a new segment starts at position (n+1).
		It is now possible to return to the LZ78 algorithm.
	pauillac.inria.fr /algo/seminars/sem96-97/szpankowski.html (2207 words)

	Hacking Data Compression - Lesson 7
		They are known as LZ77 and LZ78, referring to the papers published by Ziv and Lempel in 1977 and 1978, respectively (the transposition of 'L' and 'Z' was made early and propagated widely).
		Instead of treating the input as a big wad of text, LZ78 breaks the input into "phrases", where each phrase is the longest matching previously seen phrase plus the first character that didn't match.
		By assigning probabilities to the branches of the tree and to future events, it can be shown that LZ78 does poorly near the start of the input when it has no information in the tree.
	www.fadden.com /fadden.com/techmisc/hdc/lesson07.htm (3137 words)

	Copmression (not definitive but a guide to some forms) - Below Top Secret General Discussion
		The LZ78 algorithm is so called, because it was derived from the initials and year the mathematicians, Abraham Lempel and Jacob Ziv officially released it in 1978.
		In order to argue the statement “LZ78 was the best lossless data compression algorithm at its conception” we must examine other techniques used at the time and those under development.
		LZ78 was not designed to be operated independently, but in combination with other algorithms.
	www.belowtopsecret.com /thread169283/pglastpost (3046 words)

	LZ
		A substitutional compression scheme which works by entering phrases into a dictionary and then, when a reoccurrence of that particular phrase is found, outputting the dictionary index instead of the phrase.
		Nearby terms: LZ77 compression « LZ78 compression « LZ compression « lzexe » lzh » LZH compression » LZW compression
		Nearby terms: LZ78 compression « LZ compression « lzexe « lzh » LZH compression » LZW compression » M
	www.linuxguruz.com /foldoc/foldoc.php?LZ (552 words)

	PowerBasic Crypto Archives - LZ78
		DESCRIPTION: LZ78, like LZ77, has slow compression but very fast decompression.
		LZ78 is faster than LZ77 but doesn't always achieve as high a compression ratio as LZ77.
		NOTES: The biggest advantage LZ78 has over the LZ77 algorithm is the reduced number of string comparisons in each encoding step.
	www.pbcrypto.com /view.php?algorithm=lz78 (296 words)

	LZ77 (Site not responding. Last check: 2007-10-10)
		As of 2004 the most popular LZ77 based compression is called DEFLATE ; it combines LZ77 with Huffman coding.
		LZ78 never became as popular as LZ77 for the first few decades after it introduced LZ78 was somewhat of a patent minefield in the United States while LZ77 is not patented.
		The popular form of LZ78 compression was the LZW algorithm a modification of the LZ78 made by Terry Welch which proved to a patent minefield.
	www.freeglossary.com /Data_compression/LZ77_78 (346 words)

	RFC 3051 (rfc3051) - IP Payload Compression Using ITU-T V.44 Packet Method (Site not responding. Last check: 2007-10-10)
		1.2 Background of LZJH Data Compression LZJH is similar to the algorithm described in [LZ78] although it also has aspects which are similar to the algorithm described in [LZ77].
		As such, it provides the execution speed and low memory requirements of [LZ78] with compression ratios that are better than [LZ77].
		A typical [LZ78] compression algorithm, such as V.42bis, is not suitable for an IPComp application since it takes too long to build up its dictionary, resulting in poor compression ratios on IP datagrams that are compressed independently.
	www.faqs.org /rfcs/rfc3051.html (1714 words)

	Citations: Some Asymptotic Properties of the Entropy of a Stationary Ergodic Data Source with Applications to Data ... (Site not responding. Last check: 2007-10-10)
		LZ78 grows a tree, while observing the incoming source strings, in a way that ensures that, asymptotically, most code words are typical sequences for the source.
		....the past two decades, and is now relatively well understood [26, 17] LZ78 grows a tree, while observing the incoming source strings, in a way that ensures that, asymptotically, most code words are typical sequences for the source.
		LZ78 grows a tree, while observing the incoming source strings, in a way that ensures that, asymptotically, most codewords are typical sequences for the source.
	citeseer.ist.psu.edu /context/92508/0 (3458 words)

	LZW coding algorithm
		LZW is a so-called commercial version of LZ78.
		The LZW algorithm uses the same principles and ideas as LZ78 does, while adding several technical improvements over LZ78.
		As it can be seen from the demonstrated examples of compression using LZ78 and LZW, these algorithms achieve maximal efficiency when the length of the input string is of infinitely long size.
	www.cs.technion.ac.il /Labs/Isl/Project/Projects_done/VisionClasses/DIP/Lossless_Compression/node18.html (634 words)

	Interactive LZW Compression (Site not responding. Last check: 2007-10-10)
		In 1977, they published a paper on "sliding-window" compression, and followed it with another paper in 1978 on "dictionary" based compression.
		These algorithms were named LZ77 and LZ78, respectively.
		made a modification to LZ78 which became very popular and was dubbed LZW (guess why).
	www.cs.sfu.ca /cs/CC/365/li/squeeze/LZW.html (573 words)

	Recenze: Slovníkové algoritmy komprese (2/1) (Site not responding. Last check: 2007-10-10)
		Dále se pak již zabýval jenom slovníkovými metodami komprese a to konkrétně LZ77 a LZ78.
		LZ78 byl vysvětlen ve dvou variantách - běžné a zpožděné.
		V běžném LZ78 se na výstup posílají dvojice - index do slovníku na nejdelší shodující se úsek a následující znak, přičemž přitom se do slovníku přidá (jako nová položka) onen úsek rozšířený o ten následující znak.
	artax.karlin.mff.cuni.cz /~zajio1am/texts/practics/review2.html (322 words)

	comp.compression Frequently Asked Questions (part 1/3)
		(Y coding, a variant of LZ78) ftp://wuarchive.wustl.edu/usenet/comp.sources.unix/volume24/yabbawhap/part*.Z ftp://ftp.inria.fr/system/arch-compr/yabba.tar.Z Contact: Dan Bernstein .Z: compress for Unix ('the' LZW algorithm) It is likely that your Unix system has 'compress' already.
		Claims 4 and 12 are very general and could be interpreted as applying to any LZ algorithm using hashing (including all variants of LZ78): 4.
		(c) LZ78 - One form of the original LZ78 algorithm was patented (4,464,650) by its authors Lempel, Ziv, Cohn and Eastman.
	www.uni-giessen.de /faq/archiv/compression-faq.part1-3/msg00000.html (12484 words)

	LZ78 coding algorithm
		The LZ78 coding algorithm also referred to as dictionary-based coding algorithm.
		Hence for infinitely long input string the position (and therefore the binary representation of it) of that maximal substring is unbound, thus complicating coding.
		If the input string is relatively small, the algorithm doesn't have time to build sufficiently large dictionary for efficient coding.
	www.cs.technion.ac.il /Labs/Isl/Project/Projects_done/VisionClasses/DIP/Lossless_Compression/node17.html (578 words)

	Citations: A general practical approach to pattern matching over Ziv-Lempel compressed text - Navarro, Raffinot ...
		Along these lines, string search in compressed text was developed for the compression paradigm of LZ78 [52] and its subsequent variant LZW [50] as described in [30] 44] A more challenging problem is that of fully compressed pattern matching when both the pattern and text strings are....
		Along these lines, string search in compressed text was developed for the compression paradigm of LZ78 [45] and its subsequent variant LZW [43] as described in [23] 35] A more challenging problem is that of fully compressed pattern matching when both the pattern and text strings are....
		....of the former work to multipattern searching on LZ78 LZW was later presented [KTS 98] Based on Aho Corasick [AC75] they achieve O(m 2 n R) time and O(m 2 n) space to find all the occurrences of the patterns, where this time m is the total length of all the patterns.
	citeseer.ist.psu.edu /context/413649/245073 (3791 words)

	FactorSequence (Java Excecises from 5th and 6th Semester) (Site not responding. Last check: 2007-10-10)
		The numbers of factors generated by the LZ78 parsing of the sequence.
		Returns the number of factors produced by the LZ78 parsing of the text.
		Each factor is printed out in a separate line, in the order they appear in the text, with its serial number, its ancestor's serial number, its new character, length and a string representation of the factor itself.
	wanda.fh-aargau.ch /i/ia02gers/java3/doc/neobio/alignment/FactorSequence.html (639 words)

	DataCompression.info - LZ78/LZW and derivatives (Site not responding. Last check: 2007-10-10)
		This topic encompasses the LZ78 algorithm and its descendant, LZW.
		LZ78 is one of two seminal compression algorithms developed in the late 1970s.
		The seminal LZ78 paper which spawned LZW, GIF, and an entire academic industry.
	datacompression.info /LZW.shtml (1257 words)

	Sad day... GIF patent dead at 20
		This is not the same as LZ78 or LZW, but many people confuse it as such.
		However, the derivative of LZ78 called LZW is popular, for reasons that will soon be clear.
		[LZ78] Abraham Lempel, Jacob Ziv; Compression of Individual Sequences Via Variable-Rate Coding, IEEE Transactions on Information Theory September 1978.
	www.kyz.uklinux.net /giflzw.php (1535 words)

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