Author: Uri Blass
Date: 08:28:49 10/08/01
Go up one level in this thread
On October 08, 2001 at 10:42:41, Paul wrote: >On October 08, 2001 at 09:31:57, Uri Blass wrote: > >>On October 08, 2001 at 07:29:04, Bernhard Bauer wrote: >> >>>On October 07, 2001 at 21:39:52, Robert Hyatt wrote: >>> >>>> >>>>2. You can tone down (or even disable) the null-move search. You can >>>>try sel=2/3 (the default) then sel=2/2, sel=1/1, and finally sel=0/0 which >>>>will turn null-move off. This will further reduce the search depth and overall >>>>strength. >>>> >>> >>>From my experience sel=0/0 doesn't turn null-move completely off. >>>Here an example with sel=0/0 >>> >>>[D]4B/8/6N/5p/1r4p/6pk/7b/4K2Q w - - >>> >>> >>> (4) 6-> 1.90 -0.44 1. Bc6 Rb1+ 2. Ke2 Rxh1 3. Nf4+ Kh4 >>> 4. Bxh1 Kg5 5. Ke3 >>> (3) 7 1.96 -0.22 1. Bc6 Rb1+ 2. Ke2 Rxh1 3. Nf4+ Kh4 >>> 4. Bxh1 Bg1 5. Bg2 Bd4 >>> 7 2.75 ++ 1. Kd2!! >>> (2) 7 3.79 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 >>> (2) 7-> 6.29 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 >>> 8 8.14 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 >>> (2) 8-> 14.57 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 >>> 9 20.50 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 10. Nf4 >>> (2) 9-> 42.50 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 10. Nf4 >>> 10 1:05 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 10. Nf4 Bxf4 >>> (2) 10-> 2:22 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 10. Nf4 Bxf4 >>> 11 3:35 0.00 1. Kd2 g2 2. Qe1 g1=Q 3. Qh4+ Kg2 4. >>> Bc6+ Re4 5. Bxe4+ fxe4 6. Qxg4+ Kh1 >>> 7. Qxe4+ Qg2+ 8. Ke3 Qxe4+ 9. Kxe4 >>> Bg3 10. Nf4 Bxf4 11. Kxf4 Kh2 >>> time=5:00 cpu=201% mat=4 n=142525014 fh=89% nps=474k >>> ext-> chk=10823921 cap=287226 pp=207595 1rep=668532 mate=112510 >>> predicted=0 nodes=142525014 evals=28834988 >>> endgame tablebase-> probes done=0 successful=0 >>> hashing-> trans/ref=47% pawn=99% used=99% >>> SMP-> split=1018 stop=90 data=7/32 cpu=10:05 elap=5:00 >>> >>> >>>Kind regards >>>Bernhard >> >>I am not sure if the problem here is null move pruning. >> >>The problem may be that programs need to know that there is a chance to win in >>KN vs something(otherwise they may evaluate it as not more than a draw and stop >>to search) >> >>There are programs without this knowledge so they cannot see that >>1.Bc6 Rb1+ 2.Ke2 Rxh1 3.Bg2+ is leading to a forced mate. >> >>Deep Fritz with the default parameters(null move pruning) has no problem to find >>the win because it has this knowledge that king and knight can mate. >> >>Uri > >Hi, > >I'm sure Bernhard is right here, checked with my own program (no endgame >knowledge) and the only thing that helps here is turning of recursive nullmove. >Just one nullmove per branch is still ok, but with recursive nullmove mine >doesn't get a winning score. You are right that the reason for Crafty is null move pruning but there are also other reasons to fail to find the right move(Junior cannot see that white wins because of the fact that it believes that knight cannot win). > >I think that Deep Fritz has a smarter kind of nullmove than older versions of >Fritz (double nullmove or whatever). > >Groetjes, >Paul Yes I know that there are cases when Deep Fritz fails to find moves because of null move pruning but not in this case. I guess that there are positions when it turns off null move pruning(it may be logical to do it in some simple positions when the number of moves of the opponent is small). Uri
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