Author: Omid David Tabibi
Date: 14:45:02 11/20/02
Go up one level in this thread
On November 20, 2002 at 17:39:26, Martin Giepmans wrote: >On November 20, 2002 at 16:19:29, Omid David Tabibi wrote: > >>On November 20, 2002 at 16:04:50, Martin Giepmans 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 >>> >>> >>>If I'm not mistaken this is the well known "verification search" with >>>one modification: no verification in the verification search. >>>Am I right? >>> >> >>The classical verification search as introduced by Plenkner comes to detect >>zugzwangs. Verifeid null-move pruning as presented in the paper, constructs a >>smaller search tree with greater tactical strength in middle games (in addition >>to detecting zugzwangs). >> >> >>>Another question: >>>your results in table 5 seem convincing, but what about table 4? >>>Are these results statistically significant? (my guess is no ..) >>> >> >>For a good estimate of the growth of the search tree as we go deeper, see Table >>3 and Figure 4 (which present ECM test positions searched to a depth of 11 >>plies). >>The WCS test positions were mainly used for testing the tactical strength >>(results in Table 5). Table 4 was provided just for the sake of completeness. >> >> >>>Martin > >I see that I reduced the numbers of the tables (R=1 ;)) >What I wanted to write is that table 6 is convincing while table 5 is IMO not. > >Combining table 4 and 5 my impression is that - from a time perspective - >R=3 might be better than verified R=2. (you mean verified R = 3, don't you?!) Even though standard R = 3 constructs a smaller search tree, the problem with it, is that it is too risky. Except DIEP which uses a fixed R = 3, I don't know of any program that uses that value due to its high risk. >Compared to R=3 verified R=2 solves about 3% more positions but is about 40% >slower! > >Martin
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