Author: Vincent Diepeveen
Date: 19:05:15 11/21/02
Go up one level in this thread
On November 21, 2002 at 11:14:24, Robert Hyatt wrote: Just go for a 2 minute single cpu implementation. But of course you will find that R=2 always will outperform already his verification search with 1 ply reduction. You can implement it quicker his algorithm by doing next after nullmove: int Search(alfa,beta,depthleft,allowingnull) { .. if( !allowingnull && nullmoveok ) { .. try nullmove if( score >= beta ) { // score returned by nullmove score = Search(alfa,beta,depthleft-1,true); // last parameter to prevent another reduction next position if( score >= beta ) { StoreInHashtableAndKillerTable(..); return score; } } } .. This is a more elegant way to implement it, and it was already done years ago and published in ICCA journal. That's pretty quickly done in crafty Bob :) >On November 21, 2002 at 10:15:47, Bernhard Bauer wrote: > >>Hi Omid, >> >>would you implement your pruning technique in crafty so the benefits could be >>tested by everybody? >>That way we would have the best comparison. >>regards >>Bernhard > >I am working on this. I'll certainly post the results when I get it to work >right. >It is a bit tricky if you try to do it cleanly... > > >> >>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
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