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Subject: Re: new thoughts on verified null move

Author: Tony Werten

Date: 19:25:02 11/23/02

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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 )

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

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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