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

Author: Uri Blass

Date: 03:25:17 11/21/02

Go up one level in this thread

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 let the algorithm to work without zugwzang detection and first results seems
not to be good

Some positions I get at the same depth and
the only position so far in the gcp test suite that I got at smaller depth for
tactical reasons is
[D]5rk1/1r1qbnnp/R2p2p1/1p1Pp3/1Pp1P1N1/2P1B1NP/5QP1/5R1K w - - 0 1

I am going to try it in 10 sedconds per move and get resulkts in half an hour.


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