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

Author: Robert Hyatt

Date: 08:13:10 11/21/02

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On November 21, 2002 at 04:52:13, Omid David Tabibi 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...
>>
>
>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...

I am working on it.  :)  It is a bit more complex as I pass a 0/1 flag already
that says
"do null at next ply or don't do null at next ply".  that needs to be modified
to a four-state
flag, one bit says "no verifications beyond this point" the other says "don't do
null move at
next ply only".

As you might guess I have screwed this up 10 times already and the tree gets
real big or
real small real quick.  (and it is real wrong too)..  :)



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