Author: John Merlino
Date: 07:38:46 05/31/03
Go up one level in this thread
On May 31, 2003 at 01:00:06, Jon Dart wrote: >Arasan had this position on ICC against messchess a while ago: > >[D] Q7/8/3k4/8/5p1P/4p2K/4Bq2/8 w - - > >Here Arasan played Qf3. This is a mistake because after Qxf3 Bxf3, the >position is drawn. Seeing this requires knowledge. After the exchange, >White will have the "wrong" bishop and a rook Pawn, and so cannot win >despite being nominally ahead in material. Arasan had access to 5-man >tablebases, but those don't help here because the position after the >exchange has 6 total pieces. Chessmaster 9000, on a P4-2.4, has no problem avoiding Qf3, and believes Qb8+ wins: Time Depth Score Positions Moves 0:00 1/4 1.68 8300 1.Qg2 Qe1 2.Qg6+ Kc7 3.Qf7+ Kb6 0:00 1/5 1.90 19854 1.Qg2 Qe1 2.Qg6+ Kc7 3.Qf7+ Kb6 4.Qf6+ Kc5 5.Qe5+ Kc6 0:00 1/6 2.17 72792 1.Qg2 Qxg2+ 2.Kxg2 Ke5 3.Kf3 Kf5 4.h5 Kg5 0:00 1/7 0.10 131874 1.Qg2 Qxg2+ 2.Kxg2 Ke5 3.Kf3 Kf6 4.Kxf4 Kg6 5.Kxe3 0:02 1/7 1.35 477296 1.Qb8+ Ke6 2.Bc4+ Kd7 3.Qb5+ Kd6 4.Qd5+ Ke7 5.Qg5+ Kd6 6.Qg2 Qd2 7.Qe2 Ke5 0:02 1/7 1.61 568962 1.Qf3 Qxf3+ 2.Bxf3 Ke6 3.Kg4 Ke5 4.Be2 Ke4 0:02 2/8 0.10 573784 1.Qf3 Qxf3+ 2.Bxf3 Ke6 3.Kg4 Kf6 4.Kxf4 Kg7 5.Kxe3 0:05 2/8 1.24 1016907 1.Qb8+ Kd5 2.Qb5+ Kd6 3.Qd3+ Ke7 4.Kg4 Qg3+ 5.Kh5 Qf2 6.Qe4+ Kd6 7.Qd4+ Ke6 8.Bc4+ Ke7 9.Qe5+ Kd8 0:07 3/9 1.26 1619634 1.Qb8+ Kd5 2.Qb5+ Kd6 3.Qd3+ Ke7 4.Kg4 Qg3+ 5.Kh5 Qf2 6.Qc4 Kf6 7.Qb5 Qg3 8.Qg5+ Ke6 9.Qxg3 fxg3 0:22 4/10 1.53 4771806 1.Qb8+ Kd5 2.Qb5+ Kd6 3.Kg4 Qg3+ 4.Kh5 Qg8 5.Qg5 Qd5 6.Qxd5+ Kxd5 7.Kg4 Ke5 8.h5 1:04 5/11 2.14 13437598 1.Qb8+ Kd5 2.Qb5+ Kd6 3.Kg4 Qg3+ 4.Kh5 Qg8 5.Bf3 Qg3 6.Qd5+ Ke7 7.Qe5+ Kd8 8.Bc6 Kc8 9.Qd6 Qg7 10.Qxf4 2:50 6/12 2.53 36888904 1.Qb8+ Kd5 2.Qb5+ Kd4 3.Kg4 Qg3+ 4.Kf5 Qh3+ 5.Kg5 Qg3+ 6.Bg4 f3 7.Qd7+ Kc3 8.Qc6+ Kd4 9.Qxf3 Qe5+ 10.Qf5 Qg7+ 11.Kf4 Qc7+ 12.Kf3 Qc6+ 13.Kg3 Qh1 >One way to test for the presence of this knowledge is this position: > >[D] 8/8/3k4/8/5p1P/4pQ1K/4Bq2/8 b - - > >where Black should play Qxf3. If White plays Qf3, CM9000 sees a "draw" with the queen trade in less than a second: Time Depth Score Positions Moves 0:00 1/3 1.05 306 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 0:00 1/4 1.14 908 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Ke4 0:00 1/5 1.11 2986 1...Qxf3+ 2.Bxf3 Ke5 3.Kg2 Kd4 4.Kf1 0:00 1/6 1.33 7827 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Ke4 4.h5 Ke5 5.h6 0:00 1/7 0.10 19709 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:00 2/8 0.10 128461 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:00 3/9 0.10 149860 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:00 4/10 0.10 206288 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:01 5/11 0.10 367220 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:03 6/12 0.10 752610 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:06 7/13 0.10 1711231 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 0:19 8/14 0.10 4947986 1...Qxf3+ 2.Bxf3 Ke5 3.Be2 Kf6 4.Kg2 Kg7 5.Bf1 jm
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