Author: Christophe Theron
Date: 08:11:25 03/19/98
Go up one level in this thread
On March 19, 1998 at 04:25:22, Ernst A. Heinz wrote:
>On March 18, 1998 at 15:12:07, Christophe Theron wrote:
>
>>You are right. My point was to show that null move or related techniques
>>had a significant impact on this position.
>>
>>Unfortunately, others parameters biased the result. So here is another
>>position given by Chrilly Donninger in his famous paper from ICCA
>>Journal, Sep 93:
>>
>>White:
>>Pawn b4
>>Rook d4
>>King f2
>>
>>Black:
>>Pawn a6 b5 h2
>>Rook g6
>>King h1
>>
>>White to move. The key is 1.Rd1+, which is mate in 7. After 1...Rg1,
>>black is in zugzwang. White plays for example 2.Rf1, and wins.
>
>"DarkThought" is an aggressive null move searcher and finds 1. Rd1+!
>in iteration #2 after just 464 nodes.
>
>It returns the mate score in iteration #8 after 4380 nodes.
>
>=Ernst=
Well done!
Note that what is interesting is not when the key move is found (it can
be found by pure luck), but when the program announces mate.
Being an "agressive" null mover, DarkThought sure has a good zugzwang
detection scheme. I suppose you don't just turn null move off when there
is only one piece left? It would be very ineffective in most endgames...
Especially rook endgames.
It seems that some of the programs I tested (CM4000 for instance) simply
use null move in the last, say, 6 or 7 plies. This is a shy policy, that
should make an "agressive" null mover laugh. :)
Christophe
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