Author: Andrew Williams
Date: 05:41:59 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'.
>
I don't understand what you mean by the "fail-soft move"?
>Regards,
>
>Steve Maughan
It doesn't take PostModernist (on my Athlon 1200) very long at all to see the
problem with Qxh6:
10> 198 0 14906 1.Qxh6 b4 2.Qh3 h5 3.Kg3 Nf5 4.Kf4 Kf7
10= 215 0 41916 1.Qxh6 Ne6 2.Kg3 b4 3.Kf2 f5 4.Ke2 a4 5.Qh2
11> 208 0 75603 1.Qxh6 Ne6 2.Kg3 b4 3.Kf2 a4 4.Qh2 f5 5.Qd6
11= 214 0 79964 1.Qxh6 Ne6 2.Kg3 b4 3.Kf2 a4 4.Qh2 f5 5.Qd6
12> 214 0 99721 1.Qxh6 Ne6 2.Kg3 b4 3.Kf2 a4 4.Qh2 f5 5.Qd6
12= 219 0 139014 1.Qxh6 Ne6 2.Kg3 b4 3.Kf2 a4 4.Qh2 f5 5.Qd6
13> -522 2 513766 1.Qb8 Ne8 2.Qxe8 Qf8 3.Qxb5 f5 4.Kf4 Qd6
5.Kg5 a4 6.Qxa4 Qg3 7.Kf6 Qxe3
13= -419 4 746241 1.Qb8 Ne8 2.Qxe8 Qf8 3.Qxb5 h5 4.Kg3 Qd6
5.Kh3 Qd8 6.Qb7 g5
14> -439 6 1198282 1.Qb8 Ne8 2.Qxe8 Qf8 3.Qxb5 h5 4.Kg3 Qd8
5.Qb7 f5 6.Kh3 g5 7.Kg3 h4 8.Kh3
14= -429 6 1264249 1.Qb8 Ne8 2.Qxe8 Qf8 3.Qxb5 h5 4.Kg3 Qd8
5.Qb7 f5 6.a3 g5 7.a4 h4 8.Kh3
Andrew
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