Author: Drexel,Michael
Date: 13:07:23 01/08/04
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On January 08, 2004 at 15:29:51, Mike S. wrote: >On January 08, 2004 at 14:17:52, Drexel,Michael wrote: > >>I can reproduce it with Cb-native Crafty 19.06 and Crafty 19.08. >> >>Crafty 19.06 - Hiarcs 9 >>8/6r1/8/5p1B/5N2/4k1K1/8/8 w - - 0 1 >> >>Analysis by Crafty 19.06 CB: >> >>1. = (-0.01): 137.Bg6 Rxg6+ >>2. = (-0.01): 137.Ng6 f4+ 138.Kh4 Rh7 139.Ne5 Rxh5+ >>3. -+ (-#15): 137.Kh3 Kxf4 >>4. -+ (-#15): 137.Kh2 Kxf4 > >I cannot reproduce Bg6?? with cb-native Crafty 19.06 on a Pentium 3/700 MHz, >using 4-piece tbs. (+ all rook vs. rook-tbs which don't matter here): I temporary removed the endgame tb KRPKN from my tablebase directory and got this: New game 8/6r1/8/5p1B/5N2/4k1K1/8/8 w - - 0 1 Analysis by Crafty 19.06 CB: 1. = (-0.01): 1.Ng6 f4+ 2.Kh4 Rxg6 2. -+ (-8.92): 1.Bg6 Ke4 2.Ne2 Rxg6+ 3.Kf2 Rc6 4.Ng3+ Ke5 5.Nf1 Rc2+ 6.Ke3 Ra2 7.Kd3 Kf4 8.Kd4 Rf2 9.Ne3 Rd2+ 10.Kc5 Kxe3 11.Kb4 f4 12.Kc3 3. -+ (-#15): 1.Kh3 Kxf4 4. -+ (-#15): 1.Kh2 Kxf4 New game 8/6r1/8/5p1B/5N2/4k1K1/8/8 w - - 0 1 Analysis by Ruffian 1.0.2: 1. = (0.00): 1.Bg6 Rxg6+ 2.Nxg6 f4+ 2. = (0.00): 1.Ng6 f4+ 2.Kh4 f3 3.Bxf3 Kxf3 3. -+ (-#16): 1.Kh2 Kxf4 2.Kh3 4. -+ (-#16): 1.Kh3 Kxf4 2.Be2 > >Maybe it's not a bug, but one of these (seemingly inavoidable) nullmove effects >when zugzwang is involved. It seems to me, Bg6?? can be produced when the engine >- obviously - misses the reply Ke4, which puts Black in zugzwang. Maybe you are right and it is a Nullmove problem. However a strong chess engine shouldn't blunder in such a simple endgame and this is certainly avoidable. Michael Nimzo 8 seems >also to be affected by this nullmove problem in this position: > >Crafty 19.06 - Hiarcs 9 >8/6r1/8/5p1B/5N2/4k1K1/8/8 w - - 0 1 > >Analysis by Nimzo 8: > >137.Bg4 > -+ (-8.92) Depth: 1/11 00:00:00 >137.Ng6 f4+ 138.Kh4 Rh7 139.Ne5 Ke4 140.Nc4 Rxh5+ 141.Kxh5 f3 > = (-0.19) Depth: 1/11 00:00:00 > ³ (-0.60) Depth: 8/22 00:00:00 >137.Bg6 Rxg6+ 138.Nxg6 > = (-0.08) Depth: 8/22 00:00:00 > = (0.00) Depth: 23/44 00:00:57 32546kN, tb=1791 > >The problem seems to disappear immediatly when I switch to multi-pv mode: > >Analysis by Nimzo 8: > >1. = (-0.05): 137.Ng6 f4+ 138.Kh4 Rc7 139.Bg4 Rc5 140.Be2 Rc1 141.Bg4 Rg1 >142.Ne5 >2. -+ (-4.76): 137.Bg6 Ke4 138.Kf2 Kxf4 139.Be8 Ra7 140.Bc6 Ra2+ 141.Kf1 Ke3 >142.Bd5 > >Regards, >M.Scheidl
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