From: Andrew Wagner <wagner.andrew@...>
Date: 2010-08-18T00:01:57+09:00
Subject: Re: can i do this in ruby? a simulation process

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Ah, I see your point. Very interesting indeed. Is it reasonable to guess
that it would take a very, very long time in this case?

On Tue, Aug 17, 2010 at 10:41 AM, Jean-Julien Fleck <
jeanjulien.fleck@gmail.com> wrote:

> 2010/8/17 Andrew Wagner <wagner.andrew@gmail.com>:
> > Well, it may be interesting, but not in terms of the question originall=
y
> > asked. Actually, I'm not sure what you could ask to make it interesting
> if
> > buses are going in both directions, as I would expect the average resul=
t
> to
> > be no change in the number of people currently in either city.
>
> Don't be fooled by the apparent simplicity of the question :o)
> Random walks have many many interesting behaviors, one of which is
> that they can go as far as you like from the origin in a time you can
> estimate (from a probabilistic viewpoint).
>
> The most simple realisation is the 1D random walk:
> - choose an origin
> - flip a coin to decide if you should go right or left
> - go there
> - flip a coin...
> - etc.
>
> For sure, as the problem is symetrical on right and left, the mean
> value of the displacement is 0. But if you rather ask yourself the
> question: "how far can I go from the origin" (either on the right or
> on the left), then you can estimate how much time you need to achieve
> this goal within a given probability.
>
> In the OP problem, it would read: how much time do you need to
> transfer 500 people either from A to B or from B to A with the given
> set of rules.
>
> Cheers,
>
> --
> JJ Fleck
> PCSI1 Lyc=C3=A9e Kl=C3=A9ber
>
>

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