Author: Peter Fendrich
Date: 16:06:08 11/19/98
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On November 19, 1998 at 17:35:20, Will Singleton wrote: > >On November 19, 1998 at 16:03:58, Peter Fendrich wrote: > >>On November 19, 1998 at 15:43:56, Will Singleton wrote: >> >>>All, >>> >>>I am using a null-move error finder that works like this: if a null move causes >>>a beta cutoff, I set a flag instead of returning the null move score. If the >>>regular search then doesn't cause a cutoff, it's a failure. >> >>I hope I understood this right: >>You are using this function as a "debugging" tool and not in your ordinary >>search engine, or...? > >Yes, as a debugging tool. > > >>> >>>This happens in several of the wac positions, causing problems. One solution >>>I've heard of is to disallow null moves in the principle variation. Since I >>>generally ignore the pv during the search, I'd have to do a fair amount of >>>coding to test this. >>> >>>Does restricting null moves in the pv guard against null-move failures? >> >>No it doesn't. A null move error might be the reason why a variation didn't >>became the pv in the first place and that doesn't change with this restriction. > >Right, I had just figured this out. > > >>Another problem with this is that the pv and it's branches take up most of the >>search time. The null move approach is most valuable right here! >> > >That's another good point. btw, I don't do a zugzwang test, just disallow null >moves in the endgame. How about you? > >Will The only thing I do is to generate at least one legal move before doing a Null move cutoff. But only in endgame situations and only when beta >= DRAWSCORE. I don't know if it's worth the extra time spent but it makes me feel better... An article about Zugzwang is: Plenkner, S. (1995). A Null-Move Technique Impervious to Zugzwang. ICCA Journal, Vol. 18, No. 2, pp. 82-85. (N) The proposed method didn't appeal to me at that time for some reason that I don't remeber, so I didn't even try it out. Maybe later on... :) //Peter
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