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Subject: Re: Verified Null-Move Pruning, ICGA 25(3)

Author: Robert Hyatt

Date: 21:12:19 11/26/02

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On November 26, 2002 at 21:47:00, Omid David Tabibi wrote:

>On November 26, 2002 at 20:02:06, Robert Hyatt wrote:
>>On November 26, 2002 at 16:21:00, Omid David Tabibi wrote:
>>>On November 26, 2002 at 15:58:06, Gian-Carlo Pascutto wrote:
>>>>On November 26, 2002 at 15:55:56, Omid David Tabibi wrote:
>>>>>So it is reasonable that on every program starting from a certain depth >adaptive null-move pruning will always construct a smaller search tree.
>>>>Don't you mean the other way around?
>>>Yes :-)
>>>Starting from a certain depth, verified null-move pruning will always construct
>>>a smaller search tree than the adaptive one.
>> I am doing some testing now.  First thing I noticed is that for WAC, the
>>measurement went down very significantly for your algorithm.  And I have not
>>anything such as turning null-move off when low material happens, since your
>>idea will
>>catch the zug problems.
>>I am playing a match between old and new, and at the moment the result is
>>5 wins, 2 losses, 13 draws, new version is ahead.  Not enough games, but it is
>>More as I get more info...
>Definitely interesting...
>BTW, since Crafty has strong extensions, I suggest that you also try reducing
>the depth by 2 plies (instead of 1) on fail-high reports. In the "Conclusions"
>section I reported that in this case the tactical strength was lower than std
>R=2 on occasions; but considering the fact that its search tree was also far
>smaller, it is still an interesting option.
>In the paper, my goal was to present an algorithm tactically stronger than std
>R=2, and with smaller search tree. In practice however, other values might work
>even better.

Intuition tells me that 1 or 2 is wrong.  That is should be some sort of
proportional value insteadk.  I've been fiddling with the adaptive depth
and the extension limit as well, playing with scaling it proportionally rather
than lopping things off in a static way...  I think that reducing the depth by
some percentage might make more sense...

But I will fiddle and test a while and report back if I find anything that
improves it further, since it is your idea...

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