Author: Steve Maughan
Date: 05:20:24 04/10/02
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
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