Author: Uri Blass
Date: 06:59:56 10/08/01
Go up one level in this thread
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 Here is a better position In this position white can win by Bc6 but some programs(not Deep Fritz) cannot see it because of null move pruning [D]4B3/8/p5N1/P4p2/1r4p1/6pk/7b/4K2Q w - - 0 1 Some programs really cannot see that white is winning and here I know that it is because of null move pruning. Here is Tiger's evaluation some moves later: New position [D]8/8/p7/P4p2/5Np1/6p1/4K2b/6kr w - - 0 1 Analysis by Chess Tiger 14.0: 5.Ke1 -+ (-13.67) Depth: 15 00:00:00 126kN 5.Ke1 -+ (-14.57) Depth: 15 00:00:00 160kN 5.Ke1 -+ (-13.67) Depth: 16 00:00:00 160kN 5.Ke1 -+ (-13.67) Depth: 17 00:00:00 176kN 5.Ke1 -+ (-14.57) Depth: 17 00:00:01 317kN 5.Ke1 -+ (-13.67) Depth: 18 00:00:01 317kN 5.Ke1 -+ (-13.67) Depth: 19 00:00:01 345kN 5.Ke1 -+ (-14.57) Depth: 19 00:00:02 767kN 5.Ke1 -+ (-13.67) Depth: 20 00:00:02 767kN 5.Ke1 -+ (-13.67) Depth: 21 00:00:02 816kN (Blass, Tel-aviv 08.10.2001) Uri
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