Author: Omid David Tabibi
Date: 12:04:13 11/20/02
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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
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