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Subject: Re: Silly question

Author: Albert Bertilsson

Date: 11:05:51 12/12/03

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On December 12, 2003 at 13:47:20, Jaime Benito de Valle Ruiz wrote:

>Does your program use hash tables in perft to store just nodes for a given
>depth?
>
When doing perft if depth to search is larger than two, it looks in the hash
table if has already been calculated.

When a calculation for a certain depth is done, the result is written in the
hash table if depth is larger than two. If the position is already used I
overwrite only if nodes of the new calculation is larger than the existing item,
that way I make sure not to overwrite positions that it has taken long time to
calculate with fast calculated positions.

I store the key, nodes and depth for each position.

>Maybe for low depths using hash tables does not compensate for the extra
>processor cicles, but maybe for higher depths is ok considering all the
>transpositions that will occur in the tree.
>
>Ok, I'm probably re-descovering the gunpowder again and maybe everybody knows
>this already... but the perft in my program does NOT use the hash tables
>(although it update them with every "make"); it just verifies the correctness of
>the move generator and the make/unmake functions.
>
>I guess that using more hash memory in Sharper reduces the analysis time so
>much... otherwise it makes no sense.
>
>Just wondering,
>
>  Jaime



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