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Subject: Re: Extensions and Hashing

Author: Bas Hamstra

Date: 06:13:13 10/18/00

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On October 18, 2000 at 08:06:23, David Rasmussen wrote:

>I was wondering about a potential "bug" or at least "unwanted feature" of the
>way hashing and extensions affect eachother in, say, Crafty.
>
>The problem is basically this:
>
>In Crafty, whenever depth is used for other purposes than searching (that is
>hashing and nullmove), the extension factor isn't included. That means that a
>search that essentially asked for a depth=5 + extensions=3 == 8 ply search, will
>return with success from the hashprobe if the draft is just 6 or 7. Shouldn't
>the depth parameter ALWAYS be used with relevant extensions for the search to be
>(at least more) theoretically correct ?
>
>Am I making sense?

I think I know what you mean. I store always as draft the depth that is actually
searched below this node. So if I normally would search 5 ply, but there is 1
extension, this node is searched at 6 ply. So store draft=6.

Now when the search asked for a 6 ply depth, and there was no extension, the
hashrecord with draft=6 could theoretically be returned.

I believe Crafty does something different, that I too don't understand.


Regards,
Bas Hamstra.














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