Author: Vincent Lejeune
Date: 01:55:49 07/11/02
Go up one level in this thread
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.
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