Author: Bas Hamstra
Date: 06:45:49 11/15/99
Go up one level in this thread
On November 15, 1999 at 07:29:16, Vincent Diepeveen wrote: >On November 14, 1999 at 22:58:19, James Robertson wrote: > >>On November 14, 1999 at 22:16:33, Will Singleton wrote: >> >>>On November 14, 1999 at 21:45:26, William Bryant wrote: >>> >>>>I recently found that my null threashold is set to low, and I am experimenting >>>>with different level. >>>> >>>>I am curious what other people have found works for them. >>>> >>>>Do you count pieces or pieces and pawns? >>>> >>>>How may pieces or pieces and pawns must be present for the side on move >>>>to allow a null move? >>>> >>>>Thanks in advance. >>>> >>>>William >>>>wbryant@ix.netcom.com >>> >>>I originally had a threshold of around 3 pieces per side, but now I allow >>>endgames as long as someone has a piece. This is further modified by a >>>blocked-pawn term, which disallows null if most pawns are blocked. I think. >>>So, I don't detect zug like some others attempt to do. >>> >>>I only use R=2, but I know others alternate between 2 and 3 depending on the >>>situation. >>> >>>Will >> >>What are the advantages/disadvantages of alternating between R=2/3? Does having >>some entries with R=3 cause problems with the hash table? > >The difference between R=2 and R=3 is marginally, however for DIEP >R=2 needs a lot more nodes than R=3. > >Something interesting though is what happens the last few ply. > >At R=2 you are tempted prune the last 3 ply with quiescencesearch. > >At R=3 you are doing the last 4 ply, which means that you prune >2 moves of your opponent. > >For some programs that don't detect much in qsearch this might be >a problem. > >Everyone has to figure out whether R=2 is better for him or whether >he can do R=3 too. > >Some alternatives is using a combination: first nullmove R=3 and >all nullmoves after the first one R=2. > >I am no longer doing that though. I use everywhere R=3 now. >Bad luck for a few positions in LCT test and bs2830 testset! > >Obviously a nullmoving program with R=3 needs 3 ply more than >with R=2 to find Kh2-g3!! > >I guess everyone has to figure out his own reduction based upon >node reduction. If R=3 gives you a time reduction of 50%, then >i bet it's a good idea to use R=3 instead of R=2 ! > >>James > >Vincent I have seen a few cases where R=3 used more nodes than R=2 to reach a given depth. First iterations R=3 did better than R=2 (less nodes), but suddenly it chokes and on the end used even more nodes than R=3. Since that I gave up on R=3. However R=3 near the root and R=2 the rest works fine for me. I don't see the "choking problem". Regards, Bas Hamstra.
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