Newsgroups: comp.ai,comp.ai.philosophy,comp.ai.alife
From: stevem@comtch.iea.com (Steve McGrew)
Subject: Re: rand() - implementation ideas [Q]
Organization: New Light Industries, Ltd.
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In article <jqbE05zJw.BAK@netcom.com>, jqb@netcom.com (Jim Balter) wrote:
>>I would go so far as to say ALL large patterns CAN be compressed even when NO
>>global pattern can be found, simply because if you take small enough local
>>sections of the stream, there are bound to be repeating groups;  These
> repeating
>>groups MAY be reverse engineered to create an algorithm.....
>
>There is a fallacy here.  I suggest you check out the comp.compression FAQ.
>The number of sequences that can be expressed in n bits is 2**n.  Any
>algorithm that compresses some to a smaller number of bits will necessarily
>expand others to a greater number of bits.

        The reasoning must be based on the idea that the algorithm has to be 
transmitted along with each sequence.  Otherwise, it seems that you could just 
agree ahead of time that any repeating sequence of the form 1,1,1,--- can be 
represented as 1,n -- and that you will only bother to compress it that way if 
n is longer than, say, ten.  In any long series of sequences, or any long 
sequence, there will probably be some such subsequences and they will end up 
being compressed (slightly).  However, if the decompression algorithm has to 
be transmitted with each sequence there would be a lot of useless baggage 
carried along that would outweigh the slight amount of compression.  If the 
decompression algorithm is only transmitted along with those sequences that 
need to use it, it would need to be bigger (I think); again outweighing the 
slight compression.




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