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Subject: Re: question about futility pruning and positional evaluation

Author: Vincent Diepeveen

Date: 03:26:04 12/08/00

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On December 07, 2000 at 14:11:43, Robert Hyatt wrote:

>On December 07, 2000 at 13:56:31, Bert van den Akker wrote:
>
>>In a previous question about Futility pruning Vincent Diepeveen mentioned:
>>
>>>Futility pruning is very dubious. It sure speeds you up, but it's
>>>dubious and tends to give you slight positional
>>>differences that make a program play positional
>>>a lot weaker.
>>
>>Can sombody explain me why Futility pruning tends to give slight positional
>>differences?
>>
>>BvdA
>
>Same thing happens with null move and any other sort of pruning that discards
>a branch here and there.  If you discard a branch that somehow contributes to
>the PV score, then the PV score will change.  Anything that perturbs the shape/
>size of the tree will potentially change the PV score...

The positional effect of nullmove and futility can be best described
as the effect on the landscape of a handgun and an atomic bomb.





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