Author: Robert Hyatt
Date: 12:27:26 04/25/02
Go up one level in this thread
On April 25, 2002 at 13:49:42, Dann Corbit wrote: >On April 25, 2002 at 13:26:43, Robert Hyatt wrote: > >>On April 25, 2002 at 12:39:36, J. Wesley Cleveland wrote: >> >>>On April 25, 2002 at 02:54:03, Andreas Herrmann wrote: >>> >>>>Hi, >>>> >>>>I want to implement double nullmove in my chess engine again. Now i'm searching >>>>for Zugzwang postions, which should be solved by double nullmove instead of >>>>normal nullmove. >>>>Another question: How much time costs the double null move in the average. >>>>I have tested it in some positions, and my engine needs about 30 to 40 percent >>>>more time for the same search depth. Is that normal or is that to much. >>> >>>That seems like far too much. Are you reducing the search depth again for the >>>second nullmove and only doing it when the first nullmove causes a cutoff? You >>>might also not want to do it too near the leafs, i.e. if the first nullmove goes >>>directly into your quiescence search. >> >> >>One simple test... determine how often, in normal positions, the _second_ null- >>move search fails high. Whenever it does, the the first null-move search fails >>low and is useless. that is probably where the cost is being exposed... >> >>In zug positions, the second fail high will cause the first to fail low, which >>prevents zug problems. But if it also causes a large number of normal positions >>to fail this test as well, then it is losing part of the advantage of null-move >>in general... > >I had a notion about double null move -- > >Implement double null move in the place where normally you will just turn null >move off [except for check]. Use your regular null move algorithm as always, >but when conditions indicate null move is not a good idea, switch to double null >move. If it was easy to identify positions where a null-move might cause problems, the problem would already be solved. :)
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.