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Subject: Re: A test position for chess programs(importance of tablebases)

Author: Dieter Buerssner

Date: 11:13:24 01/19/01

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>I have nothing to tell you I'm afraid, but I would like you to tell *me*
>something :) My program slows to a crawl in a soup of tablebase accesses!
>Yours seems to be pretty speedy even though you said it also slows down.
>Mine approaches 10 kN/s iso the usual 200 kN/s if I remember correctly ...
>
>What's the trick? My program goes recursively down the tree, and the first
>thing it does at every ply is check the tb's if there are 5 pieces or less.
>If that succeeds it returns with the proper score. Otherwise it goes on
>with the usual hash lookup etc.
>
>Is there anything you can help me with (other than 'look at the source' :)?
>I'd like to see the mate 39/40 too :)

I do store EGTB scores in the hash tables. They are specially flagged
and stored as exact scores. I first probe the hash table, and then EGTBs.
This will avoid many disk accesses. Also, I ignore the depth stored
in the hash, for EGTB positions, because the information will be valid
for any depth.

Nevertheless, sometimes I only get about 20% of the normal speed, when
very many TB accesses are done.

Good luck,
Dieter




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