Re: Random data cannot be compressed

In article <p743t3dt5ac32bjhfvqld6st12fb739dr0@[EMAIL PROTECTED]
>,
 Steve Schafer <steve@[EMAIL PROTECTED]
> wrote:

> On Thu, 06 Mar 2008 19:08:02 -0800, Ron Garret <rNOSPAMon@[EMAIL PROTECTED]
>
> wrote:
> 
> >Sure.  But if D is random then the length of the decompression
algorithm 
> >plus the data will be at least as long as D.
> 
> You persist in answering questions that were never asked, and refuting
> assertions that were never made.

The statement that started this sub-thread was:

> When they [scientists] say stupid things (e.g. ... "random data
> cannot be compressed"), I am likely to re*****s their credibility.

And somewhere downstream you wrote:

> WHEREAS: You're completely missing the point. This isn't about
> compressing random data IN GENERAL. This is about compressing a SPECIFIC
> data set, which happens to have been created using a random process.
> 
> In the following, D is a constant that has exactly the same value as the
> "plain text" that we wish to compress. Given any plain text (randomly
> generated or not), we can obviously create a constant D that has that
> plain text as its value.
> 
> Here is the algorithm (pseudocode) to compress it to one bit:
> 
>  IF plainText = D THEN
>    return 1
>  ELSE
>    return 0
>  ENDIF
> 
> And here's the associated decompression algorithm:
> 
>  IF compressedData = 1 THEN
>    return D
>  ELSE
>    return ""
>  ENDIF
> 
> Do you get it now? For every SPECIFIC data set, we create a new pair of
> SPECIFIC compression and decompression algorithms. 

So not only was the assertion made, you yourself made it.  You 
specifically claimed that any data D can be compressed down to one bit.  
But the way you did it was cheating.  All you did was to relabel D from 
"data" to "code".  The reason this is cheating is that there is no 
actual distinction between data and code.  The total number of bits that 
you need to actually reconstruct D using your method is more than the 
number of bits in D.  So you have not actually compressed D at all.

rg