Re: Compression of random binary data

From	Sylvia Else <sylvia@not.at.this.address>
Newsgroups	sci.physics
Subject	Re: Compression of random binary data
Date	2016-07-13 16:29 +1000
Message-ID	<dum5f5FrdhhU2@mid.individual.net> (permalink)
References	<87b8a1c6-e14c-47f7-9647-52f4ab874054@googlegroups.com> <dujd1nF7366U1@mid.individual.net> <6fce807e-6f42-4836-990c-76f44add2f2a@googlegroups.com>

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On 13/07/2016 6:29 AM, Double-A wrote:
> On Monday, July 11, 2016 at 10:20:58 PM UTC-7, Sylvia Else wrote:
>> On 12/07/2016 3:50 AM, jonas.thornvall@gmail.com wrote:
>>> What kind of statistic law or mathematical conjecture  or is it even a physical law is violated by compression of random binary data?
>>>
>>> I only know that Shanon theorised it could not be done, but were there any proof?
>>>
>>> What is to say that you can not do it if the symbolic representation is richer than the symbolic represenatation of the dataset.
>>>
>>> Isn't it a fact that the set of squareroots actually depict numbers in a shorter way than their actual representation.
>>>
>>> Now the inpretator or program must know the rules. And i have very good rules to make it happen.
>>>
>>
>> If you consider n bits of data, then there are 2^n different
>> combinations. If your compression of the data is to be reversible, then
>> your compression has to produce 2^n different bit sequences (of varying
>> lengths, typically). If your compression produces some sequences that
>> are shorter than n bits, then it has to produce others that are longer
>> than n bits, otherwise it's impossible to have 2^n different sequences.
>>
>> If some combinations are much more frequent than others, then you can
>> make an overall gain by using shorter sequences for them, at the expense
>> of longer sequences for the rarer combinations.
>>
>> For random data, where each possible combination is equally likely,
>> you're not going to come out ahead.
>>
>> Sylvia.
>
>
> This is true of truly random binary data.  However if any information is being transmitted, then there is a strong likelihood that some combinations will be more frequent that others, and thus compression could be effective.
>
> Double-A
>

The OP expressly identified the data as being random, so that won't be 
the case.

Sylvia.

Thread

Compression of random binary data jonas.thornvall@gmail.com - 2016-07-11 10:50 -0700
  Re: Compression of random binary data xxein1@att.net - 2016-07-11 13:12 -0700
  Re: Compression of random binary data Sergio <invalid@invalid.com> - 2016-07-11 15:42 -0500
  Re: Compression of random binary data Double-A <double-a3@hush.com> - 2016-07-11 13:58 -0700
    Re: Compression of random binary data Poutnik <poutnik4nntp@gmail.com> - 2016-07-11 23:12 +0200
  Re: Compression of random binary data "nuny@bid.nes" <Alien8752@gmail.com> - 2016-07-11 15:20 -0700
    Re: Compression of random binary data Sergio <invalid@invalid.com> - 2016-07-11 21:29 -0500
  Re: Compression of random binary data Lofty Goat <rlwatkins@gmail.com> - 2016-07-11 17:48 -0500
  Re: Compression of random binary data Fabian Russell <fb@zen.info> - 2016-07-11 23:39 +0000
    Re: One _never_ knows if data is truly random or not. Fabian Russell <fb@zen.info> - 2016-07-12 14:33 +0000
      Re: One _never_ knows if data is truly random or not. Poutnik <poutnik4nntp@gmail.com> - 2016-07-12 18:37 +0200
    Re: One _never_ knows if data is truly random or not. benj <benj@nobody.net> - 2016-07-12 19:26 -0400
  Re: Compression of random binary data Sylvia Else <sylvia@not.at.this.address> - 2016-07-12 15:20 +1000
    Re: Compression of random binary data Double-A <double-a3@hush.com> - 2016-07-12 13:29 -0700
      Re: Compression of random binary data Sylvia Else <sylvia@not.at.this.address> - 2016-07-13 16:29 +1000
  Re: Compression of random binary data Michael J. Strickland <michael06582@comcast.net> - 2016-07-14 00:54 -0400

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