Author: Martin Giepmans
Date: 14:39:26 11/20/02
Go up one level in this thread
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. Compared to R=3 verified R=2 solves about 3% more positions but is about 40% slower! Martin
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