Author: John Merlino
Date: 11:25:34 04/10/02
Go up one level in this thread
On April 10, 2002 at 08:20:24, Steve Maughan wrote: >I came across this position. > >[d]6k1/6np/5ppq/pp1p4/3Pp1K1/4P3/P6Q/8 w - - > >I first encountered this position back in ~1987 in Eric Hallsworths excellent >newsletter - it was with regard to improvements in Richard Lang's engine. I >thought I'd see how todays programs compare. > >The whole point of the position is that after the obvious Qxh6 black can play >Nh5, trapping queen and allowing the Queenside pawns to promote. So the >position is a good test of how an engine handles trapped pieces and pawn >promotion. > >I tested the engines on my 1.5 GHz P4 with 96 Mb of Hash. I recorded the time >for the programs to show that Qh6 is negative and the time to suggest an >alternative (usually Qb8+). These are the results: > >Program Negative Alternative (Qb8) >Fritz 7 56 sec > 10 min >Crafty 18.14 2 sec 15 sec >Tiger 23 secs > 10 min >LGoliath 1.5 7 sec 24 sec >Junior 7 2 min 27 sec > 10 min >Monarch 5 secs 23 secs >Nimzo 7.32 3 secs > 10 min >Shredder 6.02 6 sec 1 min 55 sec >Yace 2 secs 11 secs > >As you can see many top programs struggle to suggest a better move. The normal >scenario is that they see the problem associated with Qh6 but then 'freeze' >while searching Qb8. Monarch has no specific knowledge in this position so I >was surprised that it did so well - null move will be disabled for most of the >search so maybe this is the problem with the other programs. I also wonder if >the others are doing Internal Iterative Deepening which *may* help (Monarch >does). My other thought is that maybe this position would be solved quicker if >the fail soft move was recorded along with upper bounds (alpha) since this would >give the search and may prevent the 'freeze'. > >Regards, > >Steve Maughan Chessmaster, on a PIII-600, sees Qxh6 is bad in 8 seconds, and switches to Qb8+ after 1:57... Time Depth Score Positions Moves 0:00 1/3 1.93 1007 1.Qxh6 Nf5 2.Qh3 h5+ 3.Kf4 0:00 1/4 1.84 2712 1.Qxh6 Nf5 2.Qh3 h5+ 3.Kf4 Kf7 0:00 2/5 1.84 4613 1.Qxh6 Nf5 2.Qh3 h5+ 3.Kf4 Kf7 0:00 2/6 1.91 11276 1.Qxh6 Nf5 2.Qh3 h5+ 3.Kf4 Kf7 4.Qg2 b4 0:00 3/7 2.01 24937 1.Qxh6 Nf5 2.Qf4 Kf7 3.Qc7+ Ke6 4.Qc8+ Ke7 5.Qc5+ Ke6 6.Qc6+ Ke7 0:01 4/8 2.16 64927 1.Qxh6 Nf5 2.Qf4 Kg7 3.Qc7+ Kh6 4.Qxa5 Nxe3+ 5.Kh3 Kg5 6.Qxb5 0:02 5/9 1.32 159367 1.Qxh6 Nh5 2.Kh3 b4 3.Kg2 a4 4.Kf2 b3 5.axb3 axb3 0:04 6/10 0.72 291365 1.Qxh6 Nh5 2.Kh3 b4 3.Kg2 a4 4.Kf1 b3 5.axb3 axb3 6.Kf2 b2 0:08 7/11 -7.89 618009 1.Qxh6 Nh5 2.Kh3 b4 3.Kh4 a4 4.Kg4 b3 5.a3 f5+ 6.Kh4 b2 7.Qg5 b1=Q 1:57 7/11 -4.70 9736906 1.Qb8+ Ne8 2.Qxe8+ Qf8 3.Qd7 h5+ 4.Kh3 Qf7 5.Qxb5 Qe6+ 6.Kh2 Qd6+ 7.Kh1 h4 8.Qxa5 h3 2:21 8/12 -4.73 11978311 1.Qb8+ Ne8 2.Qxe8+ Qf8 3.Qd7 h5+ 4.Kh3 Qf7 5.Qxb5 Qe6+ 6.Kh2 Qd6+ 7.Kh1 h4 8.Qxa5 h3 9.Qa8+ Kf7 3:52 9/13 -4.76 20069814 1.Qb8+ Ne8 2.Qxe8+ Qf8 3.Qd7 h5+ 4.Kh3 Qf7 5.Qxb5 Qe6+ 6.Kh2 Qd6+ 7.Kh1 Qd8 8.Qe2 h4 9.Qg4 g5 10.Qe6+ Kh7 jm
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