[aklug] Re: [OT] Re: random bits vs random Hex

On Wed, May 29, 2013 12:26 pm, Arthur Corliss wrote:
> On Wed, 29 May 2013, bryanm@acsalaska.net wrote:
>
>> I don't know enough to address entropy, but I can say that changing
>> from binary triplets to decimal digits leaves some of the pattern space
>> unused (i.e. 8 and 9). In other words, the same data takes up more space,
>> leaving open the possibility for an algorithm to compress it back to close
>> to its original size.
>
> If this were true that we'd be able to get great compression on any data,
> random or not. By your logic, compressing binary data should be awesome,
> since there's only two choices: 1 or 0.

That's not what I'm saying at all. I'm talking about unused pattern space.
As an extreme example, imagine representing binary data by letting each
*byte* represent either a 0 or a 1. Obviously, there would be tremendous
opportunity for compression. The same thing happens (to a lesser degree)
in my binary triplet -> decimal digit conversion. In each case, there
are some possible values for each data element that will *never* be used.

I'm speaking mathematically, and don't claim to know how to implement an
algorithm to take advantage of this property.

> You can't cheat around the basic problem of pattern recognition by changing
> how the same data is presented. Choosing to evaluate smaller chunks of data
> is a zero sum game because you either have to inflate your translation maps
> or look for longer pattern strings than you would in larger chunks. In the
> end, it's the repeatability of data chunks, regardless of presentation,
> which will determine compressability.

The idea of pattern recognition for the purpose of data compression
intrigues me, though I've never fully researched the details.

--
Bryan Medsker
bryanm@acsalaska.net
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