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Subject: Re: How far can you take pure "brute force"?

Author: Sune Fischer

Date: 00:49:28 11/28/02

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On November 28, 2002 at 03:43:14, scott farrell wrote:

>On November 27, 2002 at 14:02:29, Stan Arts wrote:
>
>>Hello!
>>
>>I am wondering how strong you can go by not using pruning methods like null-move
>>or futilitypruning etc. but basicly just use a minimax-type algorithm with
>>some form of alpha-beta pruning. I mean to keep the "full-width" (depth before
>>going into Q-search) depth 100% sound.
>>
>>How well would the strong programs of today do when they dis-able (in theory,
>>might not be possible ofcourse) all types of pruning except alpha-beta? (keeping
>>their Q-search and move-ordening as it is now)
>>
>>Would be interesting to find out, I mean to see the effect of very good move-
>>ordening of advanced programs etc. Also it would probably show which programs
>>depend most heavelly on their Q-search that probably makes a lot of difference
>>in strength in this case too?
>>
>>PS. Are there any strong engines/programs that do NOT use null-move, or a whole
>>lot of futility-pruning/razoring etc? And if so, which ones?
>>
>>Thanks!
>>
>>Stan
>
>Read my recent post titled "pruning vs extensions vs qsearch - are these all
>effectively the same?"
>
>My argument is that you dont need to forward prune at all, if you extend enough,
>it is virtually the same thing.
>
>Are you aware that deep blue did NOT forward prune OR null move ??? just lots
>and lots of brute force and extensions.

I don't think it is the same entirely.
One difference is that with pruning you can "undo" the extension you did
earlier. Ie. in a long variant you may extend at ply 2, but at ply 3 there are
some moves with should be pruned rather than extended.

I see no way of doing this only with (positive) extensions.

-S.



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