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Groups > comp.compression > #679

Re: a friend wants proof...

From pfraser <pete_fraser@comcast.net>
Newsgroups comp.compression
Subject Re: a friend wants proof...
Date 2012-01-02 15:03 -0800
Organization A noiseless patient Spider
Message-ID <jdtd37$daq$1@dont-email.me> (permalink)
References <18152e33-2a79-49e0-a2f6-5544d735ef5d@g21g2000pri.googlegroups.com>

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Einstein wrote:
> Ok so I know this is a silly question, so do not hit me on the head
> please.
>
> What is the highest percentage of compression on RAND data achieved?
>
> What links can you provide to show that compression on them is not
> possible?
>
> And what rewards exist (as proof of inability) for compressing RAND?
>
>
> Be kind... just act like a 10 year old is asking the question, k?

I think the counting argument is good and simple.
A random source can generate any sequence.
Some of these sequences will be compressible.

However, there's no way that you can, on average, compress
all sequences from a random source.
Imagine that you could do that.
Inevitably more than one source sequence would compress
to the same output sequence (because the output sequences
are, on average, shorter than the source sequences,
so there are fewer of them. You then have no way of knowing
which of the (two or more) distinct source sequences resulted in
the compressed sequence. So you can't decompress.

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Thread

a friend wants proof... Einstein <michaelhh@gmail.com> - 2012-01-02 12:57 -0800
  Re: a friend wants proof... pfraser <pete_fraser@comcast.net> - 2012-01-02 15:03 -0800
    Re: a friend wants proof... Michael <michaelhh@gmail.com> - 2012-01-02 23:04 -0800
  Re: a friend wants proof... Jim Leonard <mobygamer@gmail.com> - 2012-01-03 08:17 -0800
    Re: a friend wants proof... Jim Leonard <mobygamer@gmail.com> - 2012-01-03 08:18 -0800
  Re: a friend wants proof... Sebastian <s.gesemann@gmail.com> - 2012-01-08 04:52 -0800
    Re: a friend wants proof... Sebastian <s.gesemann@gmail.com> - 2012-01-08 05:03 -0800
      Re: a friend wants proof... Jim Leonard <mobygamer@gmail.com> - 2012-01-09 08:29 -0800
    Re: a friend wants proof... Alex Mizrahi <alex.mizrahi@gmail.com> - 2012-01-09 20:03 +0200
      Re: a friend wants proof... Sebastian <s.gesemann@gmail.com> - 2012-01-09 15:10 -0800

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