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Subject: Re: Doesn't appear to work for me (full data)

Author: Jeremiah Penery

Date: 21:09:49 11/20/02

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On November 20, 2002 at 22:05:29, Robert Hyatt wrote:

>On November 20, 2002 at 16:55:41, Gian-Carlo Pascutto wrote:
>>Nullmove in Deep Sjeng uses an algorithm of my own, but I can
>>switch it back to other systems easily. I did so for running
>>a few tests.
>>I made a version which uses Heinz Adaptive Nullmove Pruning
>>and a version which uses your verification nullmove.
>This would seem to be a bit harder than at first glance.  They say that
>if the normal null-move search fails high, then do a D-1 regular search
>to verify that, but while in that verification search, no further
>verification searches are done, meaning that the normal null-move search
>fail-high is treated just like we do it today..
>I'm going to experiment with this myself, just for fun, but it seems that you
>need to pass some sort of flag down thru the search calls indicating that
>you are either below a verification-search node or not so that recursive
>verification searches are not done...

I tried implementing it in Crafty, as it is done in the pseudo-code in the
paper.  I wasn't sure exactly where to place the block with the goto, and since
Crafty has no 'best' variable in search, I wasn't sure what to put there either.
 However, the algorithm did seem to work ok, though it didn't result in a
smaller tree that I could tell.  I didn't get a chance to compare it to the
normal Crafty in many positions, or for a very long time, however.

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