Computer Chess Club Archives




Subject: Re: A Null Move Enhancement?

Author: Eugene Nalimov

Date: 22:40:15 02/11/99

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On February 12, 1999 at 00:21:08, Eugene Nalimov wrote:

>On February 11, 1999 at 23:36:09, Bruce Moreland wrote:
>>On February 11, 1999 at 16:21:06, Will Singleton wrote:
>>>On February 11, 1999 at 12:52:27, Bruce Moreland wrote:
>>>>On February 11, 1999 at 08:23:10, Peter Fendrich wrote:
>>>>>Can't check that from here, but it "must be":
>>>>>"Null Move and Deep Search: Selective-Search Heuristics for Obtuse Chess
>>>>>Programs." Donninger, C. (1993).
>>>>>ICCA Journal, Vol. 16, No. 3, pp. 137-143. (A)
>>>>>I tried it but it was no hit.
>>>>>That doesn't mean that it couldn't work for other programmers in other
>>>>I expect that Ernst will respond, because he refined it and I think still uses
>>>I tried it (only allowing null-move when material imbalance exists) and found
>>>very little change.
>>>Regarding your thought about threat-detection and null-move, a reading of
>>>Anantharaman's article (ICCAJ 1991) indicates that he found little or no benefit
>>>to this.  But I remember something about you detecting mate threats with null
>>>move.  Is that right?
>>That seems to help on some tactical tests.  Sometimes I return mate scores that
>>are outside the window, and when I find one of these I extend all of the
>>So, in this case, if you let your opponent move when it is your move, and as a
>>result you are instantly mated, extend everything a little, since you might end
>>up pushing the mate over the threshold.
>>The null-move killer position is WAC 141.  It's an obvious mate that humans can
>>see easily, and some programs can see really quickly, but a generic null-move
>>program can't see it very well.
>>4r1k1/p1qr1p2/2pb1Bp1/1p5p/3P1n1R/1B3P2/PP3PK1/2Q4R w - - 0 1
>>The key is Qxf4, and it's a forced mate.
>According to Murray Campbell's lecture that he gave last year at MS,
>DB team againg beleived in singular extensions (I wrote about the
>lecture at r.g.c.c., maybe there were more details, I cannot
>remember now).

Sorry, I think that now I remember Anantharamans' threat extension,
and it differs from singular extension... But that extension is
static - he just calculated # of squares near the king that are
controlled by opponent. Bruce writes about dynamic threats
detection, it must be more powerful.


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