Messages in this thread | | | Subject | Re: How can Emacs get a unique ID per Linux reboot? | Date | Thu, 03 Jun 1999 10:43:55 -0700 | From | "G. Allen Morris III" <> |
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>>>Tim Smith said: > On Tue, 1 Jun 1999, G. Allen Morris III wrote: > > How about generating a 32bit random number at boot time. There > > is a 1 in 2**32 of getting the same number after a reboot, but > > that should not be a large problem. > > That 1 in 2**32 is the chance of duplicating any specific number in the > sequence. The chances of *some* member of the sequence being a duplicate > is much higher. This is called the "birthday paradox" because if you > pick ~30 people at random, it is highly likely that two of them will > have the same birthday.
There is no `birthday paradox' in this case. There would be a birthday paradox if the question was what is the chance of having two random numbers that are the same after picking _n_ random numbers. In this case instead of have a n/2**32 chance of a collision there would be an (n(n-1)/2)/2**32 chance of a collision. But in this case we have a single random number, and we want to know if it is the same as a single previous random number, so the odds of a collision are 1/2**32.
Allen
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