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Subject: Re: new thoughts on verified null move

Author: Omid David Tabibi

Date: 20:14:52 11/23/02

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On November 23, 2002 at 22:25:02, Tony Werten wrote:

>On November 23, 2002 at 22:14:27, Omid David Tabibi wrote:
>
>>On November 23, 2002 at 21:50:01, Tony Werten wrote:
>>
>>>On November 23, 2002 at 21:24:08, Omid David Tabibi wrote:
>>>
>>>>On November 23, 2002 at 21:09:36, Tony Werten wrote:
>>>>
>>>>>On November 23, 2002 at 20:52:01, Omid David Tabibi wrote:
>>>>>
>>>>>>On November 23, 2002 at 20:00:15, Tony Werten wrote:
>>>>>>
>>>>>>>On November 23, 2002 at 11:11:16, Christophe Theron wrote:
>>>>>>>
>>>>>>>>On November 23, 2002 at 09:22:37, jefkaan wrote:
>>>>>>>>
>>>>>>>>>oops, wasn't finished yet..
>>>>>>>>>
>>>>>>>>>>are done by using the results of the positional eval
>>>>>>>>>>to prune the q-search,
>>>>>>>>>and there using only material eval
>>>>>>>>> (haven't tried it out yet, and wouldn't
>>>>>>>>>know how to do it, but it's only an idea,
>>>>>>>>>you know.. to explore options of
>>>>>>>>>more effective branch factor reducements
>>>>>>>>>and efficient programming (besides
>>>>>>>>>lousy solutions as inline assembler
>>>>>>>>>and bitboards..
>>>>>>>>>:)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>Yes Chess Tiger does much more pruning than known (published) techniques.
>>>>>>>>
>>>>>>>>I think other top programs do it also.
>>>>>>>>
>>>>>>>>I still fail to see why the efficiency of an algorithm depends on what your
>>>>>>>>QSearch does.
>>>>>>>>
>>>>>>>>If your pruning algorithm is good, it will increase the strength of the program
>>>>>>>>regardless on how good your QSearch is.
>>>>>>>>
>>>>>>>>If your QSearch is smart, then it will increase the strength even more.
>>>>>>>>
>>>>>>>>I don't like the idea that some algorithms that have almost nothing to do with
>>>>>>>>each other would have such an influence on each other. It is indeed possible and
>>>>>>>>it probably happens all the time, but it's hard to work with such hypothesis in
>>>>>>>>mind.
>>>>>>>>
>>>>>>>>I think it's better to first assume that the kind of QSearch you do will not
>>>>>>>>interfere with the quality of the pruning algorithm used before the QSearch.
>>>>>>>>
>>>>>>>>If your QSearch sucks, it's not because you are doing a lot of pruning in the
>>>>>>>>"full width" part of the search. It's because it sucks.
>>>>>>>
>>>>>>>The paper does prove that the more your (q)search sucks, the better your pruning
>>>>>>>algoritm seems. But that's not really news.
>>>>>>>
>>>>>>
>>>>>>Does it prove that?! No, it's just my impression based on the data gathered so
>>>>>>far. Maybe a reduction of 2 (instead of 1) in case of fail-high report, will
>>>>>>work better in programs with heavy extensions and quiescence.
>>>>>
>>>>>A reduction of 20% seems to be working best in XiniX ( heavy qsearch).
>>>>
>>>>What do you mean by 20%? (you used a reduction of 1 or 2 in case of fail-high
>>>>report?)
>>>
>>>In case of a fail high I reduce the depth with 20%. ( doesn't work in your silly
>>>program :)
>>>
>>
>>Anyway, no matter what the reduction is, you are using verified null-move
>>pruning, which is good :-) In my paper I just gave a new null-move pruning
>>framework; feel free to play with the values that best fit your program.
>
>It's a no brainer to implement. If it's not bad then it's worth investigating.
>
>>
>>Even better values do exist. I've been working on them for some time and will
>>publish them in near future.
>
>If I might give an advice. For first reviews, send them it to some active
>chessprogrammers, and not to academic has beens. It will save you a lot of
>typework. ( you have been quite active on this forum lately )
>

I will. However, after posting a new method, several days of "heavy presence"
will always be needed to clear things up and answer the questions...


>BTW last time we mailed I concluded your last name was David, were does the
>Tabibi come from ?
>

My full name has always been Omid David Tabibi. But I usually use just David as
my last name in informal occasions. After ICGA put my name as "O.D. Tabibi" on
their cover, I thought it would be a good idea to use my full name here to avoid
confusion.


>Tony
>
>>
>>
>>>In XiniX I have partial extensions (PLY is 32).
>>>The addition to your idea is to give big reductions when there is still a lot of
>>>searchdepth remaining. So fe when there is 12 ply left I give more reduction
>>>than when there's 6 ply left (with a minimum of 1 ply ) That's 6*0,2 is 1,2 ply
>>>more. For XiniX that seems to make the difference between a good and a bad new
>>>idea.
>>>
>>>Tony
>>>
>>>>
>>>>
>>>>>I'm
>>>>>interessed in your idea. It's commented out in my program now, but not deleted.
>>>>>I still have to play with it some more.
>>>>>
>>>>>Despite of the negative comments you had, I don't think it's a bad idea. I'm
>>>>>just not convinced yet it's a good one.
>>>>>
>>>>
>>>>It took me several months of experiments to get convinced. After a little more
>>>>tuning and playing with different reduction values (1 or 2), I believe you will
>>>>be convinced too ;-)
>>>>
>>>>
>>>>>Tony
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>>>Tony
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>    Christophe



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