01 Jul 06
1 edit
i posted this in the posers&puzzles forum but didn't get any takers.
I think its the most complicated win i've ever encountered, so feel free to discuss guesses chess engines and all, but i think its more than solvable given a slow process, and a little help from nalimov later on (if it comes to that).
01 Jul 06
Originally posted by aginisI recommend that you just post the solution. If it's really that complicated, no human solver will get it (most won't even try). Who wants to spend hours trying to find a 10 move variation that can only be evaluated as winning with help from a tablebase?
i posted this in the posers&puzzles forum but didn't get any takers.
I think its the most complicated win i've ever encountered, so feel free to discuss guesses chess engines and all, but i think its more than solvable given a slow process, and a little help from nalimov later on (if it comes to that).
[fen]8/1R6/3k2P1/4b3/8/P1pB4/2Kn1p2/8[/fen]
Machines have proven that usually a Queen can defeat two Bishops, but what human actually wants to solve such an endgame? Too tedious!
01 Jul 06
Originally posted by BigDoggProblemwell this is from a puzzle posted at chessgames.com, and while originally people found the solution in the shortest variation at some point someone found a stronger defense, what followed was a give and take that yielded the final solution.
I recommend that you just post the solution. If it's really that complicated, no human solver will get it (most won't even try). Who wants to spend hours trying to find a 10 move variation that can only be evaluated as winning with help from a tablebase?
Machines have proven that usually a Queen can defeat two Bishops, but what human actually wants to solve such an endgame? Too tedious!
01 Jul 06
But i see your point, here is the strongest defense.
1...Nf3! 2.Bf1!! Ne1+ 3.Kb3 c2 4.Rb6+ Kd5 5.Rb5+ Kc6 6.Rb4
so far not too difficult the really hard move to see is 6...c1=Q+!!!
it looks like a draw but black can squeeze out a win.
7.Rc4+ Qxc4+ 8.Kxc4 Kd6!! 9.a4
can anyone spot the idea now?
02 Jul 06
Originally posted by aginisI would move my (black) king towards the g-pawn and capture it, because it cannot be covered in time by the white bishop. The black bishop will probably have to sacrifice itself to stop the advancing pawn on a7. But then the white king is too far away and with king and knight, black will be able to force a promotion of the pawn on f1, despite the bishop. Perhapsthat part is where tablebases may come in handy.
But i see your point, here is the strongest defense.
1...Nf3! 2.Bf1!! Ne1+ 3.Kb3 c2 4.Rb6+ Kd5 5.Rb5+ Kc6 6.Rb4
so far not too difficult the really hard move to see is 6...c1=Q+!!!
it looks like a draw but black can squeeze out a win.
7.Rc4+ Qxc4+ 8.Kxc4 Kd6!! 9.a4
can anyone spot the idea now?
[fen]8/8/3k2P1/4b3/P1K5/8/5p2/4nB2[/fen]
Too many variations to work out detailed lines though.
02 Jul 06
1 edit
Originally posted by Mephisto2exactly.
I would move my (black) king towards the g-pawn and capture it, because it cannot be covered in time by the white bishop. The black bishop will probably have to sacrifice itself to stop the advancing pawn on a7. But then the white king is too far away and with king and knight, black will be able to force a promotion of the pawn on f1, despite the bishop. P ...[text shortened]... s where tablebases may come in handy.
Too many variations to work out detailed lines though.
9...Ke6 10.a5 Kf6 11.Kd5 Bb8 12.Kc6 Ba7! (not Kxg6?? Kb7! +-)13. Kb7 Be3 14.a6 Kxg6 15.a7 Bxa7 16.Kxa7 Kf5 17.Kb6 Ke4 18.Kc5
now how to continue without letting in the white king? it takes a good visualization of how you plan to force away the bishop to realize that Ke3 fails to Kc4 Kd2 Kd4 =
the next move is critical (according to nalimov there is only one winning move)
black to play
02 Jul 06
1 edit
Originally posted by aginisEdit: nope doesn't work..
exactly.
9...Ke6 10.a5 Kf6 11.Kd5 Bb8 12.Kc6 Ba7! (not Kxg6?? Kb7! +-)13. Kb7 Be3 14.a6 Kxg6 15.a7 Bxa7 16.Kxa7 Kf5 17.Kb6 Ke4 18.Kc5
now how to continue without letting in the white king? it takes a good visualization of how you plan to force away the bishop to realize that Ke3 fails to Kc4 Kd2 Kd4 =
the next move is critical (according to nalimov there is only one winning move)
black to play
[fen]8/8/8/2K5/4k3/8/5p2/4nB2 b - - 0 1[/fen]
02 Jul 06
Originally posted by aginisMust be ... Nc2. The black king cannot come closer to pawn, nor can he get closer to the f4 square. The position white is aiming at is: his king on e1 and his knight on f4. Th bihop has no access to f1, g2 and g3, hence he cannot prevent Ne2 and promotion. The white king is helpless in the distance.
exactly.
9...Ke6 10.a5 Kf6 11.Kd5 Bb8 12.Kc6 Ba7! (not Kxg6?? Kb7! +-)13. Kb7 Be3 14.a6 Kxg6 15.a7 Bxa7 16.Kxa7 Kf5 17.Kb6 Ke4 18.Kc5
now how to continue without letting in the white king? it takes a good visualization of how you plan to force away the bishop to realize that Ke3 fails to Kc4 Kd2 Kd4 =
the next move is critical (according to nalimov there is only one winning move)
black to play
[fen]8/8/8/2K5/4k3/8/5p2/4nB2 b - - 0 1[/fen]
02 Jul 06
1 edit
Originally posted by Mephisto2indeed!
Must be ... Nc2. The black king cannot come closer to pawn, nor can he get closer to the f4 square. The position white is aiming at is: his king on e1 and his knight on f4. Th bihop has no access to f1, g2 and g3, hence he cannot prevent Ne2 and promotion. The white king is helpless in the distance.
18...Nc2!! 19.Bg2 Ke3 20.Bf1 Kd2 21.Bh3 Ke2 22.Bd7 Kd3 23.Bb5+ Kc3 24.Bf1 Ne3 25.Bb5 Nf5 26.Bf1 Ng3 27Bg2 Ne2 28.Kd6 Nf4 29.Bf1 Kd2 30.Kc5 Ke1
31.Ba6 Ne2 -+
full game at
http://www.chessgames.com/perl/chessgame?gid=1137312