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|Oct-27-09|| ||WarmasterKron: <Sneaky> Not sure if this is the one you mean, but it reminded me of this one from Tim Krabbe's site:|
click for larger view
White to play and draw, A. Herbtsmann/L Kubbel 1937
"White cannot stop the pawn by ordinary means; moves are dictated by family checks on f3; knight-stalemates; pinning stalemates by a new Queen on e1; and by the knowledge that the endgame of three Knights against one Knight is won - something first demonstrated by Troitzky. 1.Ng1 Ne3+ (Nf4+ 2.Kh1 e1N 3.Nf3+ Nxf3 stalemate) 2.Kh3 Nf4+ (2...e1N 3.Nf3+ Nxf3 with a beautiful three-Knight stalemate) 3.Kh2 Ng4+ (Not 3...e1N 4.Nf3+ Nxf3+ 5.Kg3 and White forks two Knights; or again 3...Nf1+ 4.Kh1 e1N 5.Nf3+ Nxf3 stalemate) 4.Kh1 Nf2+ (Again both promotions are, or lead to stalemate) 5.Kh2 e1N Finally. No stalemate seems in sight. 6.Nf3+ Nxf3+ 7.Kg3 (See Diagram) A fork of three Knights - Black needs them all to win. So he must play 7...Ke3, but that is stalemate once again."
|Oct-27-09|| ||beenthere240: <Patriot> A final finess is that after 1.Nb5 if black plays ... Kd3 to avoid the fork and renew the promotion threat, then 2. Na3 draws.|
|Oct-27-09|| ||MaczynskiPratten: Can't agree with <chrisowen> or <Gambitor> that White saw this when he played 55 Kf4. To deliberately force a draw from an ending with a Pawn up? Looks more like a blunder to me. |
Black's Knight is a "forking hero" - first it gobbles the White Rook and then, if White promotes to Q, it forks that as well! Still, not up to the gold standard of the Knights in Bogoljubov vs Schmid, 1949.
<SamAtoms1980>; I’d suggest that 60 b8=N as played is more accurate than 60 fxg6+ first. The latter loses the g pawn but White can comfortably hold material equality if he doesn’t exchange the pawns.
|Oct-27-09|| ||JG27Pyth: I didn't really think this was much of a puzzle because I thought underpromoting to a N to counter an enemy N fork was standard operating procedure. I think it's a case of: if you've seen it once, you've got it for always.|
|Oct-27-09|| ||beenthere240: <Endangered71> 57. Kf3 might not win because black can check on d4 and take the passed b pawn. For a while I thought 57. Ke3 might win, but then black simply takes the rook and if the b pawn advances, black forks on d5 and wins the pawn. Alterntively, if the white king goes after the knight, the knight gets back in time to stop the b pawn. However, it does seem like white was just figuring out how to get out of a blunder, since it sure looked like he was winning around move 50. Although ..... the position of the black rook behind the b pawn did offset a lot of white's advantage.|
|Oct-27-09|| ||Once: All around the world, CG.com regulars are sporting bruised foreheads and shins for alternatively doh-slapping or kicking themselves. How come so many of us struggled with this one today?|
A piece down and about to lose our precious passed pawn, it is pretty clear that we are looking for a draw. We all know about under-promotions. White doesn't have that many choices and the fact that this is a Tuesday should have been a huge clue that we were looking for something simple. So how come many of us didn't think to underpromote to a knight?
Here's my theory ...
Humans don't think like computers. We don't examine every move to see what it does - we haven't got enough time, we aren't systematic enough and we couldn't remember all the lines. Instead we look for shortcuts: visual or memory clues that point us towards moves that are more likely to be the solution.
Apart from the rarified world of problems, underpromotion is fairly rare. We generally underpomote to a rook or bishop if promotion to a queen would result in a stalemate, as in this position:
click for larger view
1. c8=Q draws by stalemate
1. c8=B or N draws by insufficient material (and immediately draws, if yesterday's kibitzing was right!)
1. c8=R wins (as does 1. Ke7 but that's boring and off-topic).
Or we underpromote to a knight if that allows a fork, as in this one:
click for larger view
White draws with 1. e8=N+, forking king and queen. Instead, 1. e8=Q? Qa1+ 2. Qa4 Qxa4#
As these are the main reasons for underpromotion (to avoid stalemate or to fork), our poor human brains can be fooled into thinking that these are the only reasons to underpromote. So we don't list the underpromotion on our Kotovian list of candidate moves. Why should we? We are not trying to avoid a stalemate or give a fork.
But today's puzzle hinges on an even rarer reason for an underpromotion. It is a little known fact that it is very hard to knight-fork another knight. Because of the peculiar way that a knight moves, it can fork all other pieces because they cannot take it back. But if you try to knight fork, say a king and knight your oppoenent will normally just play NxN. There are some rare positions where you can knight fork a knight - eg if the other knight is pinned or if the knight move comes with discovered check, but these are even rarer still.
So my home brew explanation for today's total eclipse of my meagre chess talent is that underpromotion to defend against a fork is so rare that I ruled our underpromotion without really thinking about it.
That's my excuse, poor though it is, and I am sticking with it....
|Oct-27-09|| ||Marmot PFL: Easier than yesterday, if anything.|
|Oct-27-09|| ||Patriot: <<beenthere240>: <Patriot> A final finess is that after 1.Nb5 if black plays ... Kd3 to avoid the fork and renew the promotion threat, then 2. Na3 draws.>|
Yep, very true. I saw that variation and then forgot to include it. Then I went to the Washington Post link on <al wazir>'s post and found the solution. Their solution reads:
"1.Nb5! cxb5+ (or 1...b1Q? 2.Nc3+) 2.Ka3! b1Q (or 2...b1R) stalemate; or 2...b1B 3.Kb4 Bd3 4.a4 draw."
As you point out, 1...Kd3 is a critical variation (to avoid the fork) but 2.Na3 takes care of it. Their solution didn't include this nor does it show 1...cxb5+ 2.Ka3 b1/N+.
|Oct-27-09|| ||chrisowen: <MaczynskiPratten> A spicy one isnt it, a dogged game where neither are ground down. White blows hot and cold but secures in the end.|
|Oct-27-09|| ||tivrfoa: <Weadley: So Not Funny! So Not Easy!
ARrrrrrrgghhhhh!> The same... xD|
|Oct-27-09|| ||sfm: <Sneaky, WarmasterKron>
- - -
Larsen once said: "Promotion to knight can have many good reasons - but there can only be one reason for promoting to rook or bishop: to avoid stalemating the opponent."
He was not quite right - a reason could also be to enforce a stalemate if you are the weaker part. I wonder if there is one single such example in the history of chess! But it would not be hard to construct - would it?
|Oct-27-09|| ||sfm: Who can construct a puzzle where White must underpromote to rook or bishop to avoid losing?|
|Oct-27-09|| ||BOSTER: The chess Knight is the only piece that enjoys a royal privilege: none from white pieces can attack d7 square from b8 except the Knight. The promotion b7 pawn and choosing the Knight -saves this game.
At the same time this is an example to check our routine thinking , and I'd say this is really the puzzle!|
|Oct-27-09|| ||David2009: <sfm: Who can construct a puzzle where White must underpromote to rook or bishop to avoid losing?>
click for larger view
This is part of the way there. Promoting to Q or R or N loses. Kb8 loses to ..Bxb7+ etc. Promoting to B saves the day (stalemate next move) unless Black plays ...Bb7+ allowing axb7 with counterplay. I don't know whether the counterplay is enough to save the game or not.
One variation: 1 b8=B Bb7! 2 axb7 a3 3 c8=Q a2 (there are other tries, e.g. ...Na4) 4 Qf8 threatening drawing or winning checks.
Promoting to Q loses to 1 ...Kg7! because the Q must move somewhere on the b file, allowing 2.... Bb7++# Indeed, any promoted piece other than a B must move if Black plays 1 ...Kg7
A more difficult task is to construct a puzzle where ONLY promoting to B <OR> R (as in your challenge) saves the day. I don't know if this can be done or, if so, how.
|Oct-27-09|| ||WhiteRook48: 60 b8=N, because anything else fails to 60...Nd7+
I was thinking 61 fxg6+ might be an answer, but I didn't think it was necessary
|Oct-27-09|| ||CHESSTTCAMPS: White seems tantalizingly close to victory, but the move 60.b8/Q? loses to the "royal fork" 60... Nd7+. In this line, white has no way to eliminate black's remaining pawns and can safely resign. So how does white even draw? This is surprisingly hard to find because we are conditioned to think of queen promotion as normal. Even those of us who have seen underpromotion studies have often seen it to *create* a royal fork or as a trick to avoid a stalemate. In this case, underpromotion is a necessary tool for survival: |
60.b8/N! should draw the game, unless black reflexively plays 60... Nd7+?? and white wins after all! In view of white's better king position, black should now play to force a draw with 60...gxf5 61.Kxf5 (gxf5 Nd3+ 62.Ke4 Nf2+ 63.Kf4 Nd3 ) Ne6 62.Nd7 h5 64.gxh5 (Ne5+ Ke7 changes nothing) Ng7+ eliminating white's last pawn.
The blunder 60.fxg6+? Kxg6 61.b8/N (late!) Kg5 looks like a position for a Friday puzzle.
|Oct-27-09|| ||Jimfromprovidence: <CHESSTTCAMPS> <The blunder 60.fxg6+? Kxg6 61.b8/N (late!) Kg5 looks like a position for a Friday puzzle.>|
I enjoyed your comments, as usual.
I posted earlier that it did not matter if white played 60 fxg6+ (or 60 g5) first.
I checked the Nalimov databases before I posted the line 60 fxg6+ Kxg6 61 b8/N, which is indeed a tablebase draw. (Every other move except 61 b8/N loses for white).
click for larger view
Link to the databases:
|Oct-27-09|| ||CHESSTTCAMPS: <Jimfromprovidence:>
After I posted, I regretted using the word "blunder" (implying a result-changing mistake) instead of "mistake", an error that makes things more difficult. In any case, thanks for continuing to remind us that endings like this are systematically addressed in the database. This is a great tool!|
<Once> <...That's my excuse, poor though it is, and I am sticking with it....>
After being stumped by the problem for a while before I finally got it, I made a similar argument in my post, before I read your post! I had a sneaking suspicion it would catch a few other good puzzle solvers.
|Oct-27-09|| ||TheaN: First of all, to anyone saying otherwise, 60.fxg6† can hardly lose. Even after White loses the g-pawn. Better yet, if he trades the Knights (although in a advantageous manner), it can be drawn because we are dealing with a Rook Pawn. In combination with the fact that White has a kamikaze Knight for the h-pawn instead of a traded Knight, it draws. 60.b8=N is safer because White wins a tempo with this move (Black cannot progress in that position), 60.fxg6† doesn't lose.|
Secondly, someone asked for puzzle where underpromotion with a stalemate theme avoids losing. There is one very educational position in the Stappenmethode Stap 5 book:
Black to play
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So simple, yet so intriguing. Even without the complete theme revealed, with five legal moves this puzzle shouldn't be too terrible. It's just for the educational example.
|Oct-27-09|| ||OBIT: <TheaN>Checking a tablebase, the only drawing move after 60. fxg6+ Kxg6 is 61. b8=N. I guess that proves the underpromotion is necessary but doesn't have to be done immediately. (Reading backwards a few posts, I see Jim from Providence also mentions this.) |
Cute puzzle! 1...g1=Q? loses after R1xf1, but 1...g1=B!! draws because R1xf1 is stalemate!
|Oct-27-09|| ||ComboKal: OK, so I look at the board. Right away I see it's a simple position. I can't win if I don't get that queen. If I promote now, I am forked. If I don't promote, the pawn is lost. I figure I must create a diversion, but after a few seconds I realize thats impossible. Winning is impossible! So what do I do? I figure I must capture both pawns to draw. Black can't win with just the knight. So I take a minute or two to play out all the scenarios. |
seems OK. I must somehow get that h pawn! Black must capture now at b7... Wait a second. What am I thinking? Black plays 60 ...g5+, and I am stopped cold.
seems to be the next best move. No good. Kxg6, and the king will be guarding h6. What else is there??
No good. The h pawn will pass. I get annoyed! I can't figure this out, so I click on the game.
White gets the draw. I am such an idiot!!! Sometimes I overlook the simplest solutions.
|Oct-27-09|| ||turbo231: Well once again I missed it. A very clever and amusing puzzle.|
|Oct-28-09|| ||SuperPatzer77: Sergi Shipov's brilliant move is 60. b8=N!! to save the game with a draw.|
60. b8=Q? Nd7+, 61. Kf4 Nxb8, 62. g5?! h5!, 63. Ke5 Nd7+, 64. Kf4 Nf8, 65. Ke5 gxf5!, 66. Kxf5 Ng6! (White cannot save his last g-pawn because White King is driven back into the third row).
Kudos to Sergi Shipov! This move 60. b8=N!! made me laugh aloud.
|Oct-29-09|| ||TheaN: <OBIT: <TheaN>Checking a tablebase, the only drawing move after 60. fxg6+ Kxg6 is 61. b8=N. I guess that proves the underpromotion is necessary but doesn't have to be done immediately. (Reading backwards a few posts, I see Jim from Providence also mentions this.)>|
I wasn't saying I wouldn't play 61.b8=N, but even then people were saying it would lose after 61....Kg5 but that cannot be true, and as it seems, it isn't.
<OBIT: Cute puzzle! 1...g1=Q? loses after R1xf1, but 1...g1=B!! draws because R1xf1 is stalemate!>
Yes, correct. As said, with five legal moves it isn't so difficult: the key point is the potential pin of Rf2, but with a Queen on g1 it has no relevant use. All the variations:
<1....g1=R? 2.Rcxf1 >
<1....Kh2? 2.Rcxf1 > any Rook may be played in the above two variations.
<1....g1=Q? 2.Rxf1 Qxf1 3.Rxf1† > White can only play Rcxf1, Rf2 is pinned.
<1....g1=N? 2.Rfxf1 (2.Rcxf1 stalemate 1/2-1/2) > here White should watch out for the Black swindle as Rcxf1 is stalemate.
<1....g1=B! 2.Rc2 (2.Rxf1 stalemate 1/2-1/2) 2....Bxf2† 3.Rxf2 Bg2 => and White has no choice, either stalemate or a Rook vs Bishop drawn endgame.
|Nov-08-09|| ||sfm: <David2009>
Thanks for the study.
Neat thinking - any other move than bishop forcing White into a zugzwang mate.
I'll try to re-arrange some pieces, as your version does not quite work, as White loses anyway.
But close it is!
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