Author: Andreas Herrmann
Date: 12:34:44 11/20/02
Go up one level in this thread
On November 20, 2002 at 15:04:13, Omid David Tabibi wrote: >On November 20, 2002 at 14:59:10, Andreas Herrmann wrote: > >>On November 20, 2002 at 11:43:10, Omid David Tabibi wrote: >> >>> >>> ICGA Journal, Vol. 25, No. 3, pp. 153-161, September 2003 >>> >>> >>> Verified Null-Move Pruning >>> >>> Omid David Tabibi and Nathan S. Netanyahu >>> >>> >>> Abstract >>> >>>In this article we review standard null-move pruning and introduce our extended >>>version of it, which we call verified null-move pruning. In verified null-move >>>pruning, whenever the shallow null-move search indicates a fail-high, instead of >>>cutting off the search from the current node, the search is continued with >>>reduced depth. >>> >>>Our experiments with verified null-move pruning show that on average, it >>>constructs a smaller search tree with greater tactical strength in comparison to >>>standard null-move pruning. Moreover, unlike standard null-move pruning, which >>>fails badly in zugzwang positions, verified null-move pruning manages to detect >>>most zugzwangs and in such cases conducts a re-search to obtain the correct >>>result. In addition, verified null-move pruning is very easy to implement, and >>>any standard null-move pruning program can use verified null-move pruning by >>>modifying only a few lines of code. >>> >>> >>>pdf: http://www.cs.biu.ac.il/~davoudo/pubs/vrfd_null.pdf >>>zipped pdf: http://www.cs.biu.ac.il/~davoudo/pubs/vrfd_null.pdf.zip >>>gzipped postscript: http://www.cs.biu.ac.il/~davoudo/pubs/vrfd_null.ps.gz >> >>Hi Omid, >> >>hmm seems interresting. Thanks for the paper. I will try it out in the next >>days. Did you tryd your null move extension also in pawn endgame positions where >>the most moves in the search tree are zugzwang? >> > >No I didn't conduct much experiments on various zugzwang positions. The main >benefit of verified null-move pruning is in the middle game, since it will >construct a smaller search tree with more accurate results. > >I believe that in endgames with extreme cases of zugzwang, it might be better to >turn off null-move altogether; since while verified null-move will guarantee an >accurate result, the cost of the re-searches might be too much. > >Omid. > >>Andreas i have ask you this because, before about a year i have made several trys to extend the nullmove with similar extensions like you. But i have mainly searched a way for using nullmove in pawn endgames while detecting most zugzwangs. I thought there must be a way to find the right moves if i come deep enough and without too much code in the eval. After a lot bad results i'm using again a similar R2/3 nullmove like E.Heinz with small differences. But i'm using no nullmove in pure pawn endgames. It's much to risky. In some days my other computer has time :) (after finishing the current tests) and i can make some tests with your null move extension. Andreas
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