Author: John Merlino
Date: 10:54:51 07/11/02
Go up one level in this thread
On July 11, 2002 at 04:55:49, Vincent Lejeune wrote: >On July 11, 2002 at 00:41:10, Dana Turnmire wrote: >[D]8/8/8/2pK3p/8/5N2/1P4pq/5Rbk w - - > >>-- -- -- -- -- -- -- -- >>-- -- -- -- -- -- -- -- >>-- -- -- -- -- -- -- -- >>-- -- BP WK -- -- -- BP >>-- -- -- -- -- -- -- -- >>-- -- -- -- -- WN -- -- >>-- WP -- -- -- -- BP BQ >>-- -- -- -- -- WR BB BK >> >>In this position Chessmaster 8000 (running on an AMD Athalon 1800+ system) set >>on default with a selective search of 6 takes 3'7" to find Rb1 with a score of >>3.45. >> >>Chessmaster set on 0 selective search only takes 2'41" for the same problem. >> >>Chessmaster set on 12 selective search cannot find the Rb1 move even after a >>half hour. >> >>This is what Graham Burgess says about the position in his book "The Mammouth >>Book of Chess," page 394. >> >> "Unfortunately, the standard algorithms to prune the variation tree are very >>likely to prune out the winning line, as the moves only make sense when you have >>seen to the end of the line. >> After more than 7 hours, Junior 6 (using tablebases, which one would expect to >>help speed up the assessments in some of the sidelines) considered 1 Rb1 to be >>winning, but it also thought 1 Rd1 to be equally good! Crafty 17, after several >>hours, opted for 1 Re1 or Ra1, and considered the position in either case >>(correctly) to be drawn, but did not see the winning line. >> Fritz 6, also using tablebases and with its Selectivity option set to zero, >>found the solution, including 1 Rb1 and 4 Ka8 in less than three minutes. In >>fact, it takes the same time without tablebases, so this isn't a significant >>factor here. >> The same engine, with a normal selectivity setting, is far less successful. >>1 Rb1! c4 (1...h4 2 Kc6 h3 3 Kb7 c4 comes to the ssame thing.) >>2 Kc6! h4 3 Kb7! h3 >> Even at this point, when the calculation is not so deep, some of the engines >>still take a while to find White's next move (Junior 6 and Hiarcs 7.32 are >>quickest - about 10-15 seconds to find the win; others, including Fritz 6 and >>Crafty 17, take longer, though Fritz 6 with Selectivity set to zero finds it in >>a split second). >>4 Ka8! >> Only when this position is reached do most of the engines' assesments jump >>dramatically in White's favour." >> >>I would be interested in how Chessmaster 9000 handles this problem. The Selective Search setting for Chessmaster 9000's default personality has been set to 9. So, on my modest PIII-600, it does not see the solution in less than five minutes. Not sure how well it would do on your much better hardware, though. After forcing 1.Rb1 c4, it takes almost four minutes to find Kc6: Time Depth Score Positions Moves 0:00 1/4 -2.62 1057 2.Nxh2 Kxh2 3.b4 Bf2 4.Kxc4 g1=Q 5.Rxg1 Kxg1 0:00 1/4 -2.08 1301 2.Re1 h4 3.Nxh2 Kxh2 4.Kxc4 Bf2 0:00 1/5 -2.08 2489 2.Re1 h4 3.Nxh2 Kxh2 4.Kxc4 Bf2 0:00 1/6 -1.95 7469 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.Nxh2 Kxh2 6.bxc3 0:00 1/7 -1.95 14943 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.Nxh2 Kxh2 6.bxc3 0:00 2/8 0.00 32837 2.Re1 h4 3.Rc1 h3 4.Ke4 Qe5+ 5.Nxe5 h2 6.Nxc4 0:01 3/9 0.64 60624 2.Re1 h4 3.Rc1 h3 4.Ke4 Qf4+ 5.Kxf4 h2 6.Kg3 c3 7.Nxh2 cxb2 8.Re1 0:02 4/10 0.15 146752 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qf4+ 6.Kxf4 h2 7.Nxh2 Kxh2 8.Kf3 Bb6 0:04 5/11 0.15 372284 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qf4+ 6.Kxf4 h2 7.Nxh2 Kxh2 8.Kf3 Bb6 0:09 6/12 0.00 960475 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qf4+ 6.Kxf4 h2 7.Nxh2 Kxh2 8.Rc2 Bc5 9.Rxg2+ Kxg2 0:25 7/13 0.00 2667732 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qe5+ 6.Nxe5 h2 7.c4 1:01 8/14 0.00 6715301 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qe5+ 6.Nxe5 h2 7.c4 2:42 9/15 0.00 18141353 2.Re1 h4 3.Rc1 h3 4.Ke4 c3 5.bxc3 Qe5+ 6.Nxe5 h2 7.c4 3:55 9/15 2.95 26338067 2.Kc6 h4 3.Kb7 h3 4.Ka8 c3 5.bxc3 Qb8+ 6.Rxb8 Bh2 7.Rh8 g1=Q 8.Nxg1 Bxg1 9.Rxh3+ Kg2 10.Rh7 Kf3 This should give you a reasonable idea of how long it would take to find Rb1 on your hardware (my guess would be about 5-7 minutes). jm
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