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Subject: Re: new thoughts on verified null move

Author: Omid David Tabibi

Date: 19:14:27 11/23/02

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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.

Even better values do exist. I've been working on them for some time and will
publish them in near future.


>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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