Author: Uri Blass
Date: 06:33:30 04/10/02
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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. The specific knowledge that is needed here is exactly search knowledge. Top program have not the right search knowledge in that position. Fritz almost never disable the null move so I see no reason to be surprised that you get better results than other programs. I remember that spiderchess could solve it in 1 second because of better extensions. I also wonder if >the others are doing Internal Iterative Deepening which *may* help (Monarch >does). My program needs today depth 12 to see negative score and it takes it a long time (almost 10 minutes on p800). I did not wait to see how much time it needs to find a better move(certainly more than 10 minutes) It does not do internal iterative deepening today because I had problems to do it without bugs and decided to investigate other things after I understood that it does not change much in most of the positions. I know ideas how to solve it fast without problems in other positions but my problem is to implement the ideas correctly in my program. My main problem in programming is not to have good ideas that other programs do not use but to implement them correctly. Uri
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