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From: UC445...@umcvmb.missouri.edu (John M. Kelsey)
Newsgroups: comp.compression
Subject: Yabba, Y-coding?
Message-ID: <1991Jul15.052659.29594@mont.cs.missouri.edu>
Date: 15 Jul 91 05:25:04 GMT
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   What is Y-coding?  (Any book references?)

   Is yabba's source code available via anonymous FTP?  Or is it a for-profit
product?  (I don't recall ever seeing anything either way.)

   Thanks.
   --John Kelsey, uc445...@umcvmb.missouri.edu

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From: brns...@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.compression
Subject: Re: Yabba, Y-coding?
Message-ID: <26273.Jul1518.28.4791@kramden.acf.nyu.edu>
Date: 15 Jul 91 18:28:47 GMT
References: <1991Jul15.052659.29594@mont.cs.missouri.edu>
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In article <1991Jul15.052659.29...@mont.cs.missouri.edu> UC445...@umcvmb.missouri.edu 
(John M. Kelsey) writes:
>    What is Y-coding?  (Any book references?)

It's a ``fourth corner'' to the LZW, MW, AP triangle, and like AP it
produces somewhat better results than LZW on practically all files. I
discovered it December 26 last year. Unlike LZW, MW, and AP, Y coding is
not patented.

>    Is yabba's source code available via anonymous FTP?

Yes. Look for yabbawhap in your local comp.sources.unix archive site,
volume 24. The package includes whap, an implementation of AP coding;
whap runs at similar speed to compress and produces better results in
the same amount of memory, but unfortunately it's patented. Y coding is
somewhat more complex and runs somewhat more slowly. The package
includes draft 4b of my ``Introduction to Y coding,'' which runs through
LZW, MW, AP, and Y, and presents results for all the methods on the text
corpus.

yabba and whap have been run on lots of BSD and AT&T UNIX systems, the
Acorn system, the Amiga, MS-DOS, and a few others. All the code is
public-domain.

---Dan