Author: Dana Turnmire
Date: 11:13:00 07/11/02
Go up one level in this thread
On July 11, 2002 at 13:54:51, John Merlino wrote: >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 I guess this shows when one starts playing around with created personalities the Selective Search setting may be more of a major factor that needs to be looked at when it comes to playing strength.
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