Author: Mike Hood
Date: 02:17:57 11/02/03
Go up one level in this thread
To quote the original post: "Many engines say 1 to mate and many other say 2 to mate. Why there is no consensus?" Let's take a similar example with a couple of extra pawns and see what some of the strongest Chessbase engines say: [D] 8/8/p1p5/P1P5/7Q/4K3/8/6k1 w - - 0 1 Pretty straight forward? Let's put the engines to the test. There's a lot of junk in the first analysis lines, but the final result is what matters. Analysis by Shredder 7.04: 1.Qh2+ Kxh2 ² (0.38) Depth: 1/2 00:00:00 1.Qh2+ Kxh2 ± (1.09) Depth: 1/2 00:00:00 1.Qh1+ Kxh1 ± (1.16) Depth: 1/2 00:00:00 1.Qh1+ Kxh1 ± (1.16) Depth: 1/2 00:00:00 1.Qg3+ Kf1 +- (10.89) Depth: 1/2 00:00:00 1.Qg3+ Kf1 +- (10.89) Depth: 1/2 00:00:00 1.Qf2+ Kh1 +- (11.24) Depth: 1/2 00:00:00 1.Qf2+ Kh1 +- (11.24) Depth: 1/2 00:00:00 1.Qf2+ Kh1 2.Kd3 +- (11.15) Depth: 2/4 00:00:00 1.Qg3+ Kh1 2.Kd4 +- (11.28) Depth: 2/5 00:00:00 1.Qg3+ Kh1 2.Ke4 +- (11.28) Depth: 2/5 00:00:00 1.Qf6 Kg2 2.Qxc6+ Kg1 +- (12.06) Depth: 2/5 00:00:00 1.Qf6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (12.06) Depth: 2/5 00:00:00 1.Qe1+ Kh2 2.Qe2+ Kg3 3.Qxa6 +- (14.92) Depth: 2/5 00:00:00 1.Qe1+ Kh2 2.Qe2+ Kg3 3.Qxa6 +- (14.92) Depth: 2/5 00:00:00 1.Qe1+ Kh2 2.Qe2+ Kg3 3.Qg2+ Kxg2 +- (14.67) Depth: 3/11 00:00:00 1.Qe1+ Kh2 2.Qe2+ Kg3 3.Qg2+ Kxg2 +- (14.17) Depth: 3/11 00:00:00 1.Qe1+ Kh2 2.Qe2+ Kg3 3.Qxa6 +- (11.93) Depth: 3/11 00:00:00 1.Qf2+ Kh1 2.Qe2 Kg1 3.Qxa6 +- (12.00) Depth: 3/11 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qxa6 +- (15.12) Depth: 3/11 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qh3+ Kxh3 +- (15.12) Depth: 3/11 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qf4+ Kg2 4.Qf1+ Kxf1 5.Kd4 +- (14.87) Depth: 4/12 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qb5 cxb5 +- (14.37) Depth: 4/12 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qxa6 Kg3 +- (15.08) Depth: 4/12 00:00:00 1.Qh6 Kf1 2.Qxc6 Ke1 3.Qxa6 +- (19.72) Depth: 4/12 00:00:00 1.Qh6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (#6) Depth: 4/12 00:00:00 1.Qh6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (#6) Depth: 4/12 00:00:00 1.Qh6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (#6) Depth: 5/8 00:00:00 1.Qh6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (#6) Depth: 6/10 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6/12 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6/12 00:00:00 No problems. Analysis by Junior 8: 1.Qd8 Kg2 +- (12.63) Depth: 3 00:00:00 1.Qe7 Kg2 +- (12.66) Depth: 3 00:00:00 1.Qf6 Kh2 2.Qxc6 +- (13.91) Depth: 3 00:00:00 1.Qf6! +- (14.21) Depth: 6 00:00:00 1kN 1.Qf6 Kh2 2.Qxc6 Kg3 3.Qg6+ Kh4 4.Qxa6 +- (14.37) Depth: 6 00:00:00 2kN 1.Qe1+! +- (14.41) Depth: 6 00:00:00 4kN 1.Qe1+ Kh2 2.Qf2+ Kh1 3.Qf1+ Kh2 4.Qxa6 Kg3 5.Qxc6 +- (14.83) Depth: 6 00:00:00 6kN 1.Qf2+! +- (14.84) Depth: 6 00:00:00 6kN 1.Kf3! +- (14.85) Depth: 6 00:00:00 9kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6 00:00:00 9kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6 00:00:00 9kN Identical. Analysis by Crafty 19.03: 1.Kd4 +- (11.42) Depth: 1/3 00:00:00 1.Kd4 Kf1 +- (11.14) Depth: 2/3 00:00:00 1.Qf2+ +- (11.82) Depth: 2/3 00:00:00 1.Qf2+ Kh1 2.Qf3+ Kg1 3.Qxc6 +- (18.59) Depth: 2/3 00:00:00 1.Qf2+ Kh1 2.Qf3+ Kg1 3.Qxc6 +- (18.99) Depth: 3/8 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qxa6 Kg2 4.Qxc6+ +- (19.87) Depth: 3/8 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 3/8 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 4/8 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 5/12 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6/14 00:00:00 37kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 7/17 00:00:00 120kN, tb=3 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 8/19 00:00:01 335kN, tb=10 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 9/20 00:00:02 797kN, tb=53 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 10/24 00:00:04 1774kN, tb=127 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 11/26 00:00:09 3703kN, tb=337 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 12/28 00:00:16 7733kN, tb=730 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 13/32 00:00:34 17564kN, tb=1484 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 14/36 00:01:38 54187kN, tb=3109 Identical, but there's a subtle difference. Junior and Shredder cease the analysis when they find the mate. Crafty continues ad infinitum. Analysis by Chess Tiger 15.0: 1.Qg3+ +- (12.54) Depth: 1 00:00:00 1.Qg3+ Kh1 +- (19.76) Depth: 1 00:00:00 1.Qg3+ Kh1 +- (19.76) Depth: 1 00:00:00 1.Qg3+ Kh1 2.Qf3+ Kg1 3.Qxc6 +- (19.76) Depth: 2 00:00:00 1.Qg3+ Kh1 2.Qf3+ Kg1 3.Qxc6 +- (19.76) Depth: 3 00:00:00 1.Qh6 +- (20.66) Depth: 3 00:00:00 1.Qh6 Kg2 2.Qxc6+ Kg1 3.Qxa6 +- (21.12) Depth: 3 00:00:00 1.Kf3 Kf1 +- (#2) Depth: 3 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 4 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 5 00:00:00 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 6 00:00:00 1kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 7 00:00:00 2kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 8 00:00:00 5kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 9 00:00:00 19kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 10 00:00:00 43kN 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 11 00:00:00 164kN, tb=4 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 12 00:00:01 400kN, tb=16 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 13 00:00:04 1389kN, tb=93 1.Kf3 Kf1 2.Qf2# +- (#2) Depth: 14 00:00:12 4074kN, tb=297 Chess Tiger is another engine that doesn't switch itself off after finding a Mate, but isn't a search depth of 14 rather over the top for a Mate in 2? Analysis by Fritz 8.0.0.23: 1.Qg5+ Kh2 2.Kf3 Kh3 3.Qh6# +- (#3) Depth: 4/13 00:00:00 4kN Oops. Fritz slips up. Fritz finds a Mate in 3 and stops analysing. Maybe it's a good idea to contine the analysis after all to prevent blunders like this. Analysis by Comet B60: 1.Qg4+ Kf1 +- (11.83) Depth: 1/3 00:00:00 1.Qg3+ Kf1 +- (11.91) Depth: 1/4 00:00:00 1.Qf2+ Kh1 +- (12.11) Depth: 1/4 00:00:00 1.Qc4 +- (12.20) Depth: 1/4 00:00:00 1.Qh6 +- (12.21) Depth: 1/4 00:00:00 1.Qe4 +- (12.22) Depth: 1/4 00:00:00 1.Qe4 Kf1 2.Qxc6 +- (14.32) Depth: 2/4 00:00:00 1.Qe4 Kf1 2.Qxc6 +- (14.32) Depth: 2/4 00:00:00 1.Qf6 Kh2 2.Qxc6 +- (14.44) Depth: 2/6 00:00:00 1.Qc4 Kg2 2.Qxa6 +- (14.57) Depth: 2/6 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qxa6 Kg3 4.Qxc6 +- (18.61) Depth: 2/8 00:00:00 1.Qf2+ Kh1 2.Qf1+ Kh2 3.Qxa6 Kg3 4.Qxc6 +- (18.61) Depth: 2/10 00:00:00 1.Qf2+ Kh1 2.Qf3+ Kh2 3.Qxc6 Kg3 4.Qxa6 +- (18.69) Depth: 3/10 00:00:00 1.Qg4+ Kf1 2.Qg6 Ke1 3.Qg1# +- (#2) Depth: 3/10 00:00:00 1.Qg4+ Kf1 2.Qe2+ Kg1 +- (#85) Depth: 3/10 00:00:00 1.Qg5+ Kf1 2.Kf3 Ke1 3.Qc1# +- (#2) Depth: 3/10 00:00:00 1.Kf3 Kf1 2.Qh1# +- (#1) Depth: 3/10 00:00:00 Very interesting. Is this really a Mate in 1, Ulrich? Analysis by Nimzo 8: 1.Qh5 +- (13.33) Depth: 1/11 00:00:00 1.Qh6 +- (13.47) Depth: 1/11 00:00:00 1.Qh6 +- (13.47) Depth: 1/11 00:00:00 1.Qg4+ +- (13.53) Depth: 1/11 00:00:00 1.Qg4+ +- (14.98) Depth: 1/11 00:00:00 1.Qg4+ Kh2 2.Qh5+ +- (15.23) Depth: 1/11 00:00:00 1.Qg4+ +- (15.51) Depth: 3/14 00:00:00 1.Qg4+ +- (17.06) Depth: 3/14 00:00:00 1.Qg4+ +- (#2) Depth: 3/14 00:00:00 1.Qg4+ Kh2 2.Kf3 Kh1 3.Qg2# +- (#1) Depth: 3/14 00:00:00 1.Kf3 # (#0) Depth: 3/14 00:00:00 1.Kf3 Kf1 2.Qh1# # (#0) Depth: 3/14 00:00:00 1.Kf3 Kf1 2.Qh1# # (#0) Depth: 5/17 00:00:00 Ouch! Mate in 0? Comments, Christian? I could post more examples, but this is enough. Of the seven engines tested the Mate result varies from Mate in 3 to Mate in 0. Even excluding Fritz 8, the only engine that failed to find the Mate, there's a lack of consensus.
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