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Subject: Re: Hashing is a complicated affair ?

Author: Sune Fischer

Date: 16:25:33 04/05/04

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On April 05, 2004 at 19:10:59, rasjid chan wrote:

>On April 05, 2004 at 18:58:57, Andrew Wagner wrote:
>
>This is what I learn, maybe from a cursory read of crafty's commentary
>(not source) and off I go... for Everest. It seems others are saying
>MUCH MORE.
>
>Rasjid

You need the following information in the hash:
depth - to the leaves (called draft)
score - the value returned from the node
flag - was the node (hence score) a beta, alpha or pv(exact) node?

Now when you probe from the search you have:
current_depth - to the leaves
alpha - lower window value
beta - upper window value

So you can see there are a lot of combinations, each combination
must be handled.
For instance if the hash indicates:

if (
depth>=current_depth && // draft is usable
flag == BETA &&         // it was a fail-high (lower bound)
score >= beta)       // the score is at least higher than beta, we fail-high
return beta;

-S.





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