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Subject: Re: Chess and 2bit EGTBs (win/loss/draw info only)

Author: Robert Hyatt

Date: 21:50:04 08/08/02

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On August 08, 2002 at 14:43:32, Alvaro Jose Povoa Cardoso wrote:

>If I wanted to play with EGTBs with only win/loss/draw information and no
>DTM/DTC information where would I place the probe code in the search routine?
>Taking crafty as an example it has the TB probe code placed next to the hash
>table probe code and if the current position is in a TB file it returns
>immediately because is has perfect/complete information. But with 2bit/entry
>EGTBs it just doesn't seem right to place the code there. It seems logic to me
>to place the TB probe code in the evaluation function and if a leaf node is in a
>2bit/entry TB file give it a bonus. Another possibility would be to place the TB
>probe code before calling the qsearch.
>Could someone tell me if I'm thinking correctly?
>


No.  You should probe _exactly_ where I do.  The only difference will be
the "score".  You won't be able to return a mate in N, so you will have
to doctor the score to some value that says "mate in N where N is large and
unknown."

If you probe in the eval, you will probe a million times too often.  You
should probe when you drop into a 5 piece (or smaller) ending, which only
happens infrequently and immediately after a capture only...  If you do it
at endpoints, you will get killed tactically because your search depth will
drop off _several_ plies...



>Best regards,
>Alvaro Cardoso



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