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Re: lynx-dev Options, V.Links, random

From: Doug Kaufman
Subject: Re: lynx-dev Options, V.Links, random
Date: Thu, 16 Dec 1999 19:30:10 -0800 (PST)

On Thu, 16 Dec 1999, Philip Webb wrote:

> 991215 Klaus Weide calculated: 
> > Let's say there are 20 temp files existing & kept track of by Lynx
> > at any one time, realistic with source_cache, UI pages, downloads.
> > What are the chances that, among 20 filenames drawn out of 10000
> > (with repetition),  >= 2 are the same?  I get: approximately 190/10000.
> > (Can anyone confirm, or is my math just way off? :) )
> not "approximately", exactly (grin): 1 + 2 + ... + 19 .

I am not sure which algorithm you are using to approximate this. The
exact probability is:

1 - (9999! / (9980! * 10E76))

I am not set up to evaluate the exact expression, but probably someone
on the list can give us a good approximation of its value. I suspect
that it is smaller than the above estimates. Please let me know if you
think that this is the wrong value for the probability. (This assumes
that the second draw has 9999/10000 chance of being different from the
first, the third draw has 9998/10000 chance of being different from
the first two, ..., and the twentieth draw has a 9980/10000 chance of
being different from the first 19.)
Doug Kaufman
Internet: address@hidden

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