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Subject: Re: when to store nullmove failure in hashtable?

Author: Pallav Nawani

Date: 00:30:59 09/28/04

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On September 27, 2004 at 15:32:05, martin fierz wrote:

>aloha!
>
>i just tried the following in my program:
>
>if a nullmove was tried and it failed, i saved a "nonull"-flag in my hashtable.
>when i got a hash hit, i checked whether nonull was set or not, if it was not
>set i did not attempt a nullmove.
>
>this seemed rather sensible to me - but it ended up searching about 5% more
>nodes on a fixed depth test suite.
>
>where did i go wrong? should i only hash nonull if i detect a mate threat??
>

Yes. When you detect a mate threat, hash the threat. When you revisit that
position again, Don't NULL move, but you may wish to extend.

Regards,
Pallav




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