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Subject: Re: KRRNKRR win in 290: a new record

Author: Dann Corbit

Date: 19:17:18 10/27/05

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On October 27, 2005 at 22:12:55, Dann Corbit wrote:

>On October 27, 2005 at 07:03:18, Yakov Konoval wrote:
>
>>On October 26, 2005 at 20:27:19, Dann Corbit wrote:
>>
>>>On October 20, 2005 at 10:56:15, Joshua Shriver wrote:
>>>
>>>>Interesting, a thought on compression though. Why not use bz2? It's just as easy
>>>>to implement as zip and has better compression.
>>>
>>>Bzip2 is horribly slow, both for compressing and decompressing.
>>>
>>>The extra compression gained is a small percentage.  Fine for web or ftp sites,
>>>but (I guess) a bad choice for EGTB compression.
>>>
>>
>>I did some experiments with bzip2-library. It's really slow, but gives much
>>better (about 60-80%) compression in comparison with zlib-library.
>>
>>>7-Zip has lots of algorithms implemented (including bzip2.)  The license is a
>>>bit unclear to me.
>>>
>>
>>AFAIK 7-Zip LZMA SDK has a very effective LZMA-algorithm, but using of this
>>library is really unclear. Only 2 functions are needed for EGTB-generator-
>>compression/decompression of 1 block in the RAM, but there are no such fuctions
>>in lzma.dll.
>>
>>>This looks very interesting (although license is only GPL or commercial):
>>>http://www.oberhumer.com/opensource/lzo/
>>>
>>>What is wanted in a case like EGTB is very fast decompression and very good
>>>compression.
>>
>>The main criteria for generation is very fast compression/decompression, but
>>for the final study of generation the best compression is needed.
>
>What I would want from a set of EGTB files is the fastest possible access.
>So if decomression of the block was slower than reading the decompressed block,
>then the compression is literally "a waste of time."
>
>If you need provably the best compression, then look no further:
>http://www.ii.uni.wroc.pl/~inikep/research/pasqda41b.zip
>
>According to this document:
>http://www.maximumcompression.com/data/doc.php
>pasqda41b achieved 1.3552 bits per byte against a large body of inputs.
>
>Comes with source code.  But expect it to be a slow, slow memory hog.

I looked up that program (pasqda41b), and it is designed for text files.  So it
probably won't work for EGTB files.



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