Computer Chess Club Archives




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

Author: Omid David Tabibi

Date: 02:01:31 11/21/02

Go up one level in this thread

On November 21, 2002 at 00:09:49, Jeremiah Penery wrote:

>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.

Leave alone the zugzwang detection for now (other parts don't need a 'best'

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