Message-ID:	<332B9F32.79F2@pobox.oleane.com>
Date:	Sun, 16 Mar 1997 08:20:18 +0100
From:	Francois Charton <deef AT pobox DOT oleane DOT com>
Organization:	CCMSA
MIME-Version:	1.0
To:	Benjamin D Chambers <chambersb AT juno DOT com>
CC:	djgpp AT delorie DOT com
Subject:	Re: Problems using allegro
References:	<19970312 DOT 054752 DOT 7495 DOT 0 DOT fwec AT juno DOT com> <19970315 DOT 101544 DOT 7423 DOT 14 DOT fwec AT juno DOT com>
	<332B58A4 DOT 60 AT pobox DOT oleane DOT com> <19970315 DOT 211912 DOT 7879 DOT 7 DOT chambersb AT juno DOT com>

Benjamin D Chambers wrote:
> 
> Wasn't LZW Lempel-Ziv-Welsh?  (I can never remember their names, but at
> least I know what they start with :)
> 

Yes, LZW is based on a algorithm nicknamed LZ78. It has been described in 
the article "Compression of individual sequences via variable 
rate coding", by Lempel and Ziv (IEEE transactions on Information Theory, 
vol.24 Nr 5, pp 530-536). 

Terry Welsh was the one who discovered a practical implementation of this 
algorithm (which uses a stack structure for creating the coding 
dictionnary). He published his results in 1984 in "A technique for high 
performance data compression", (IEEE Computer, Vol.17, nr6, pp8-19).

The patent for LZW was applied for by Welsh, who worked at the time for 
the Sperry Research Center, now part from Unisys.

Francois

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