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Subject: Re: Checks in the Qsearch

Author: Omid David

Date: 20:42:03 07/07/02

Go up one level in this thread


On July 07, 2002 at 21:43:47, Robert Hyatt wrote:

>On July 07, 2002 at 16:47:33, Omid David wrote:
>
>>On July 07, 2002 at 16:36:57, Robert Hyatt wrote:
>>
>>>On July 07, 2002 at 11:48:27, Omid David wrote:
>>>
>>>>On July 06, 2002 at 23:23:28, Robert Hyatt wrote:
>>>>
>>>>>On July 06, 2002 at 22:29:44, Omid David wrote:
>>>>>
>>>>>>On July 06, 2002 at 10:20:17, Robert Hyatt wrote:
>>>>>>
>>>>>>>On July 06, 2002 at 01:07:36, Ricardo Gibert wrote:
>>>>>>>
>>>>>>>>
>>>>>>>>Okay, but so what?
>>>>>>>>
>>>>>>>>>
>>>>>>>>>So perhaps the idea of "forward pruning" is foreign to us as well...
>>>>>>>>
>>>>>>>>I see no logical difference between deciding which moves are interesting and
>>>>>>>>worth looking at and deciding which moves are not interesting and not worth
>>>>>>>>looking at. It looks to me like 2 sides of the same coin, so your speculation
>>>>>>>>that "perhaps the idea of "forward pruning" is foreign to us as well..." does
>>>>>>>>not seem to be of any consequence.
>>>>>>>>
>>>>>>>
>>>>>>>However, that has been _the point_ of this entire thread:  Is DB's search
>>>>>>>inferior because it does lots of extensions, but no forward pruning.  I
>>>>>>>simply said "no, the two can be 100% equivalent".
>>>>>>
>>>>>>Just a quick point: The last winner of WCCC which *didn't* use forward pruning
>>>>>>was Deep Thought in 1989. Since then, forward pruning programs won all WCCC
>>>>>>championships...
>>>>>
>>>>>
>>>>>In 1992 no "supercomputer" played.  In 1995 deep thought had bad luck and lost
>>>>>a game it probably wouldn't have lost had it been replayed 20 times.   No
>>>>>"supercomputer" (those are the programs that likely relied more on extensions
>>>>>than on forward pruning due to the hardware horsepower they had) has played
>>>>>since 1995...
>>>>>
>>>>>I'm not sure that means a lot, however.  IE I don't think that in 1995 fritz
>>>>>was a wild forward pruner either unless you include null move.  Then you
>>>>>would have to include a bunch of supercomputer programs including Cray Blitz
>>>>>as almost all of us used null-move...
>>>>
>>>>I personally consider null-move pruning a form of forward pruning, at least with
>>>>R > 1. I believe Cray Blitz used R = 1 at that time, right?
>>>
>>>
>>>I believe that at that point (1989) everybody was using null-move with R=1.
>>>It is certainly a form of forward pruning, by effect.
>>
>>Yes, and today most programs use at least R=2... The fact is that new ideas in
>>null-move pruning didn't cause this change of attitude, just programmers
>>accepted taking more risks!
>
>
>I think it is more hardware related.  Murray Campbell mentioned R=2 in the
>first null-move paper I ever read.  He tested with R=1, but mentioned that
>R=2 "needs to be tested".  I think R=2 at 1980's speeds would absolutely
>kill micros.  It might even kill some supercomputers.  Once the raw depth
>with R=2 hits 11-12 plies minimum, the errors begin to disappear and it starts
>to play reasonably.  But at 5-6-7 plies, forget about it.

So using a fixed R=3 seems to be possible in near future with faster hardware,
doesn't it?



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