Author: martin fierz
Date: 14:51:40 04/07/02
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On April 07, 2002 at 17:22:03, Dieter Buerssner wrote: >On April 07, 2002 at 15:48:22, Terry McCracken wrote: > >>Here's an Endgame that should make _all_ chess engines really work! > >[3n2k1/p2P2p1/1p6/7Q/5q1P/8/PP6/1K6 w - -] > > >>Fritz 7 sees the draw but doesn't understand the loss after 1.Qe8+..Qf8?? >> >>Played by Mieses-NN 1903. Mieses won after Qf8??, I'll give the main line. >> >> >>1.Qe8+ Qf8 2.h5 Nf7 3.Kc2 Nd8 4.Kc3 Nf7 5.a4 Nd8 6.Kc4 Nf7 7.Kd5 Nd8 8.b4 Nf7 >>9.Kc6 Nd8+ 10.Kc7 Line > >Which would be the winning line after 2...b5. My engine unfortunately fails to >see it ... > >You give Qf8 a "??". Should it be really obvious, that tis is a bad move? > >Regards, >Dieter hi dieter, yes, it is obvious that this is a bad move. the point is something which computers are worst at, an "eternal bind". after 1. ...Qf8 2.h5, no black piece can move any more: if the king moves, black loses the queen, the queen cannot move, because it's illegal, and so the only thing to do is to shuffle the knight back and forth, because if you move it away, you lose to d8Q. so all you have to see is that after 2.h5 black can only move the knight, and white can move the king right down to c7. ...g6 at any time is met by h6-h7-h8 winning. for a human, this is really easy - we recognize the fact that black is reduced to shuffling and can ask ourselves: where would i like my king to be - i don't have to calculate anything! a computer would have to see through the whole line until the knight is lost. which is quite deep... this type of bind is causing me headaches in my checkers program, and it is a very general class of positions where chess programs are weak at too. aloha martin
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