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Subject: Re: What to do when hash table returns a Mate value?

Author: Robert Hyatt

Date: 19:32:41 01/17/03

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On January 17, 2003 at 17:27:22, Dieter Buerssner wrote:

>On January 17, 2003 at 17:08:11, Robert Hyatt wrote:
>
>>Remember that the mate scores in the search are "mate in N from the _root_
>>position."  When you store a mate score in the transposition table, you have to
>>correct it so that it is "mate in N from the current ply".  Once you do that,
>>you
>>can use the scores easily as when you get an EXACT mate score from the table,
>>you know it is mate in N from the current ply, so obviously it is mate in N+
>>something from the root position.  Adjust it correctly and you are done.
>
>I agree - of course.
>
>>You can see how I do this in crafty if you look at hash.c...
>
>Last time I looked, you were just throwing valuable information in this regard
>away. Crafty didn't store mate bounds due to the method you explained above, but
>rather stored all mate bounds as some "Mate in very many moves". I am convinced,
>that the adjustment to a mate score from root cannot be worse, and often will
>ahve advantages (more cutoffs, faster search, ...).
>
>Regards,
>Dieter


You are most likely right.  I did this a long time back when I had a
_different_ bug somewhere, and I never restored the code to adjust the mate
bounds.  Not sure why, but it is on my "to do" list...



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