Author: Vincent Diepeveen
Date: 19:19:26 11/21/02
Go up one level in this thread
On November 21, 2002 at 22:05:15, Vincent Diepeveen wrote: Small addition: when the parameter 'allowingnull' is true you must not allow transposition in hashtable either of course. >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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