Author: Uri Blass
Date: 03:25:17 11/21/02
Go up one level in this thread
On November 21, 2002 at 04:52:13, Omid David Tabibi wrote: >On November 20, 2002 at 22:05:29, Robert Hyatt wrote: > >>On November 20, 2002 at 16:55:41, Gian-Carlo Pascutto wrote: >> >>>Nullmove in Deep Sjeng uses an algorithm of my own, but I can >>>switch it back to other systems easily. I did so for running >>>a few tests. >>> >>>I made a version which uses Heinz Adaptive Nullmove Pruning >>>and a version which uses your verification nullmove. >> >>This would seem to be a bit harder than at first glance. They say that >>if the normal null-move search fails high, then do a D-1 regular search >>to verify that, but while in that verification search, no further >>verification searches are done, meaning that the normal null-move search >>fail-high is treated just like we do it today.. >> >>I'm going to experiment with this myself, just for fun, but it seems that you >>need to pass some sort of flag down thru the search calls indicating that >>you are either below a verification-search node or not so that recursive >>verification searches are not done... >> > >Exactly!! (finally someone read the article carefully) > >See Figure 3 for detailed implementation (the flag you mentioned which is passed >down as a parameter for search(), is called 'verify' in the pseudo-code). > >At first stage leave alone the zugzwang detection part (the piece of code at the >bottom of Figure 3). Due to instablilities, some programs might do a needless >re-search. First let the algorithm work fine in general, and then do the >zugwzang detection part. I let the algorithm to work without zugwzang detection and first results seems not to be good Some positions I get at the same depth and the only position so far in the gcp test suite that I got at smaller depth for tactical reasons is [D]5rk1/1r1qbnnp/R2p2p1/1p1Pp3/1Pp1P1N1/2P1B1NP/5QP1/5R1K w - - 0 1 I am going to try it in 10 sedconds per move and get resulkts in half an hour. Uri
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