random

[Tage Stabell-Kulo]

"Tim Peters" <tim.one at home.com> writes:

>[Darren New]
>> how random is the binary string "1001010010011100100"? How
>> random is the binary string "0000000000000000000"? Such questions
>> don't make any sense.

>BTW, you can find attempts to answer such questions in Knuth, Vol 2.  The
>questions not only make sense, but finding non-trivial answers is important
>in real life:  even if you have a theoretically perfect physical RNG, how
>can you have confidence in a specific real implementation?  


Knuth answers a different question.  His question is "Algorthm X
produced these bits: 010101.  Based on them, can we detect some
patterns that should refrain us from relying on this algorithm as a
source of (pseudo)random bits?"  In other words, he is analysing
sources of randomness, not whether some string is random.  An
important difference.

Randomness is interesting only for the next bit, not the ones you
already have.  Because you have them, they are not random.  Thus, the
bits 1001010010011100100 or 0000000000000000000 are not random, although 
they might have been.


 [TaSK]


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