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[dsfjdssdfsd] Any plans for drafts or discussions on here? (fwd)



From: J.A. Terranson <[email protected]>

Interesting thread going on at [email protected]. Forwarded for our 
collective interest and amusement.

---------- Forwarded message ----------
Date: Thu, 23 Jan 2014 23:38:07 +0100
From: Krisztián Pintér <[email protected]>
To: Michael Hammer <[email protected]>
Cc: "[email protected]" <[email protected]>,
    "[email protected]" <[email protected]>
Subject: Re: [dsfjdssdfsd] Any plans for drafts or discussions on here?
Michael Hammer (at Thursday, January 23, 2014, 9:49:32 PM):
>> This may get off-topic, but are there good software tools for testing
>> entropy, 
>> that could help applications determine if the underlying system is giving
>> them good input?

>disclaimer: i'm no expert, it is just what i gathered. (i'm pretty
>much interested in randomness.)
>short answer: no
>long answer: in some situations yes. if you are handed a bunch of
>data, all you can do is to try different techniques to put an upper
>limit on the entropy. for example you can calculate the shannon
>entropy assuming independent bits. then you can hypothesize some
>interdependence, and see if you can compress the data. you can apply
>different lossless compression methods. the better compression you
>find puts an upper limit on the entropy. but never a lower limit.

Consider this:  Suppose I handed you the digits of pi, the digits from the millionth digit to the two-millionth digit, and I asked you to determine if they are 'random'.  By many tests, you'd conclude that they are random.  (Or, at least 'normal' http://en.wikipedia.org/wiki/Normal_numbers ; )   But, in reality they are highly non-random, precisely because they are a million sequential digits of pi.  But you wouldn't know that, if you didn't know that.

         Jim Bell
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