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Subject: Re: To skin a cat (was Re: NULL MOVE)

Author: Thorsten Greiner

Date: 07:57:08 02/26/99

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On February 25, 1999 at 00:12:53, Don Dailey wrote:

>On February 24, 1999 at 19:16:27, Bruce Moreland wrote:
>
>>
>>On February 24, 1999 at 15:37:58, Don Dailey wrote:
>>
>>>My program is a mixture of static rules and null move.  I do null
>>>move when I have significant depth remaining, but when I am near
>>>end nodes I do a simple static attack analysis.  This has proven
>>>to be a significant improvement to my chess program.  It is faster
>>>than null move and slightly riskier, but the net affect is
>>>a stronger chess program (for me.)   Even though it's probably
>>>riskier, it does pick up things null move will miss although the
>>>converse is also true.
>>
>>Can you describe this or give examples please?  I know that some people do this
>>but I haven't the vaguest idea how it works.
>>
>>bruce
>
> [Nice story of Don Dailey deleted]
>
>I  think there are  probably  several  modern programs  that use  some
>version of this  static based selectivity,  and Rebel is  one of them.
>Rebel may not do it  anything like we did, but  it shows that there is
>more than one way to skin a cat!
>
>- Don

It seems some other chess programmers also discovered the ideas you described.
For example, Ernst Heinz of the german Dark Thought team describes a similar
idea in his paper on extended futility pruning, where they apply static
selectivity in the last three plies before the search horizon (see
http://wwwipd.ira.uka.de/Tichy/DarkThought/ for this and other papers).

Also Rainer Feldmanns (from Zugzwang) idea of FH-reductions aims at a similar
direction: At each node in the tree, they reduce the depth of the subtree by
one, if the static evaluation (backep up by some threat recognition) if >= beta.
A link to the online version of his paper is found at
http://www.uni-paderborn.de/fachbereich/AG/monien/PERSONAL/OBELIX/publications.html.

-Thorsten



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