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## Re: [Bug-gnubg] Some Questions about rollouts.

 From: Joern Thyssen Subject: Re: [Bug-gnubg] Some Questions about rollouts. Date: Mon, 4 Nov 2002 07:52:42 +0000 User-agent: Mutt/1.4i

```On Sun, Nov 03, 2002 at 04:49:16PM -0800, David Montgomery wrote
>
> > There is still one thing I don't understand, even though I have read the
> code
> > several times: Which seven rolls does it pick? How does it make the
> choice? It
> > doesn't pick random as I understand. And as I understand this it doesn't
> find
> > the order in respect of how good the rolls are either. Please explain.
>
> I haven't looked at this code in a long time, but it came from
> my program, so I think I remember how it works.  My recollection
> is that it rotates among three groups of 7 rolls, so that all 21
> rolls are represented.    That is, 1/3 of the 1-ply continuations
> are evaluated at 2-ply with one set of 7 rolls, another 1/3 are
> evaluated with a *different* 7 rolls, and the remaining 1/3 are
> evaluated with the remaining 7 rolls.
>
> The partitioning of the rolls into three groups was done with some
> effort toward evening up the luck.  For example, I tried to roughly
> balance the number of doublets and the number of individual sixes,
> fives, fours, threes, twos, and ones.
>
> It does not, however, do any analysis of which rolls are likely to
> be good or bad in the current board situation.  You can think of
> it as a "random" sample of the continuations, with a little effort
> to make it better (on average) than a truly random sample.

Do you have code for other reductions, e.g., 66%, 50% or 25%? Also, it
would be very nice to make this work for 3-ply evaluations as well.

Jørn

--
Joern Thyssen, PhD
Vendsysselgade 3, 3., DK-9000 Aalborg, Denmark
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Note: new mobile number!

```