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

Author: Omid David Tabibi

Date: 01:52:13 11/21/02

Go up one level in this thread

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...

Exactly!! (finally someone read the article carefully)

See Figure 3 for detailed implementation (the flag you mentioned which is passed
down as a parameter for search(), is called 'verify' in the pseudo-code).

At first stage leave alone the zugzwang detection part (the piece of code at the
bottom of Figure 3). Due to instablilities, some programs might do a needless
re-search. First let the algorithm work fine in general, and then do the
zugwzang detection part.

I'm looking forward to your results in Crafty...

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