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Subject: Re: negative extensions

Author: Miguel A. Ballicora

Date: 08:49:58 01/26/01

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On January 26, 2001 at 10:55:21, Severi Salminen wrote:

>
>>Inspired by the thread on extensions, I was wondering whether the idea of
>>negative extensions or reductions could be a good one.
>>
>>I mean, maybe many of the "unsound" pruning methods would be sounder if, instead
>>of just pruning, they just adjusted the resulting depth down. In that way, a
>>line would still be examined, only later.
>
>Have you tried limited razoring as described by Ernst Heinz? So, if we are at
>D=3 (distance to horizon) and material_balance+RAZOR_MARGIN<=alpha decrease
>depth to 2:
>
>if((material()+MARGIN)<=alpha)
>     depth=2;
>
>Heinz suggests values of Queen - Queen+1 to be used as MARGIN.

I have some questions:
- Where do you perform this test? at the beginning of search?
- Does this transform to a futility pruning case when you at at D=1?
- In what cases this will be reducing the tree size that null-move did not
reduced already?

Regards,
Miguel



>
>Severi



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