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Subject: Re: Verified Null-Move Pruning, ICGA 25(3)

Author: Omid David Tabibi

Date: 11:38:46 11/20/02

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On November 20, 2002 at 14:32:40, Uri Blass wrote:

>On November 20, 2002 at 11:43:10, Omid David Tabibi wrote:
>>            ICGA Journal, Vol. 25, No. 3, pp. 153-161, September 2003
>>                          Verified Null-Move Pruning
>>                    Omid David Tabibi and Nathan S. Netanyahu
>>                                   Abstract
>>In this article we review standard null-move pruning and introduce our extended
>>version of it, which we call verified null-move pruning. In verified null-move
>>pruning, whenever the shallow null-move search indicates a fail-high, instead of
>>cutting off the search from the current node, the search is continued with
>>reduced depth.
>>Our experiments with verified null-move pruning show that on average, it
>>constructs a smaller search tree with greater tactical strength in comparison to
>>standard null-move pruning. Moreover, unlike standard null-move pruning, which
>>fails badly in zugzwang positions, verified null-move pruning manages to detect
>>most zugzwangs and in such cases conducts a re-search to obtain the correct
>>result. In addition, verified null-move pruning is very easy to implement, and
>>any standard null-move pruning program can use verified null-move pruning by
>>modifying only a few lines of code.
>Some comments:
>1)If I understand correctly your idea let the computer to find every idea that
>is based on one zugzwang after enough time but not ideas that are based on more
>than one zugzwang.
>Am I right?

I think it will manage to detect almost all zugzwang positions and find the
correct move through a re-search. However, I think the most important
contribution of verified null-move pruning will be in middle game, as it will
enable a deeper, more accurate search.

>2)I guess that it is not good news for Amir Ban because it seems that most of
>the null move pruning programs like Fritz are going to earn rating when Junior
>cannot because it does not use null move prunning.

Now that many of null-move's shortcoming have been addressed, I believe Shay and
Amir will also incorporate null-move pruning in their program.



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