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Subject: Re: A Null Move Enhancement?

Author: Eugene Nalimov

Date: 21:21:08 02/11/99

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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
>>>>programs...
>>>
>>>I expect that Ernst will respond, because he refined it and I think still uses
>>>it.
>>>
>>>bruce
>>
>>
>>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
>candidates.
>
>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.
>
>bruce

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).

Eugene



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