< Earlier Kibitzing · PAGE 2 OF 2 ·
|Aug-07-09|| ||Patriot: Initial candidates: Qxh6+,Nxf7+,Rxg7,Nf6
The only one that passes the safety check is Nf6. There are so many variations but I tested what I thought to be the most critical.
24.Nf6 (threatening 25.Qxh6+ gxh6 26.Nxf7+ Rxf7 27.Rg8# and 25.Nd7 winning the exchange)
A) 24...gxf6 25.Qxh6#
B) 24...Nxf6 25.exf6 g5 26.Rxg5 hxg5 27.Qxg5 and mate next on g7 or h6.
C) 24...Qa7 is an interesting defense that is unclear.
I barely scratched the surface on this due to time constraints but decided that 24.Nf6 must be the move.
|Aug-07-09|| ||sleepyirv: Got the first move dead to rights, got what to do if it was captured by the pawn (mate) or the knight. And there was a fork with Nd7 (though I thought it would be unnecessary for a mating attack probably)|
Can I get half credit? Quarter credit?
|Aug-07-09|| ||YetAnotherAmateur: <jheiner> It looks to me like in the case of
24. Ng5 f6
is a decent response for black. A continuation might look like this:
25. Nf7+ Kg8
26. Qxh6 Rxf7
27. Nxf7 Kxf7 (else drop the knight without much to show for it)
28. Qxg7+ Ke8
29. Qg6+ Kd7
30. Qf7+ Kc6
31. Rc1+ Bc4
and the key thing about this is that while black's kingside has collapsed the black king has reached relative safety over on the other side of the board, and has even managed some level of counterplay with Rxb2 followed by an a-pawn push.
|Aug-07-09|| ||lzromeu: I do it in seconds, my first correct friday puzzle, but It was a lucky.
I see the treath, but I can't see the final sequence.|
|Aug-07-09|| ||butilikefur: <24. Nf6 Qa7> 24. Nf6 threatens 25. Qxh6+ gxh6 26. Nxf7+ Rxf7 27. Rg8+ mate so here are some alternative defenses|
24...Nxf6 25. exf6 g5 (25...Rg8 26. Rxg7 Rh4 [26...Rxg7 27. Qxh6+ Rh7 28. Qf8+ mate] 27. Nxf7+ mate) 26. Rh3 (26. Rxg5 probably also wins) 26...Kg8 (26...Kh7 27. Qxg5) 27. Rxh6 Qc5 28. Rh5
24...Qc7 25. Rxg7 Kxg7 26. Nde8+ wins the queen
<25. Rh3> and I think Black's dead
<25...Nxf6 26. exf6 Kg8 27. fxg6> or even simpler is 27. Rg3
|Aug-07-09|| ||jheiner: <YetAnotherAmateur: <jheiner> It looks to me like in the case of 24. Ng5 f6
is a decent response for black. A continuation might look like this: 25. Nf7+ Kg8.>|
26.Rxf6+ King moves 27. Qxh6#.
There are probably other responses, but Black can't mess about.
The key here is that with the lifted R on the g-file, Black is in a precarious position once the pawns start to fall.
|Aug-07-09|| ||LIFE Master AJ: It's after 1:30 PM here. (I had a chess lesson this morning.) |
I thought about the problem all night long ... I lay in bed going over the variations in my head.
After 24.Nf6!! White has seveeral threats, including a mate if Black plays 24...RxP/b2. ('?') [White plays 25.QxP/h6+!, gxh6; (forced) 26.NxP/f7+ (26...RxN/f7) and 28.Rg8 mate. (This is one of the oldest mates in all of chess. Its called the "Arabian Mate," and predates the game's move to Europe when the power of the Queen was greatly increased. It gets it's name because the mate was found in ancient Sanskrit documents.)]
After 24.Nf6!!, White also threatens a fork on d7 as well. After 24.Nf6, then 24...Qb8; (adding a protection to the back-rank); which stops the mate, but does not stop the Knight fork on d7, (winning material). 24.Nf6, Nf4; stops the mate, but does not prevent the Knight fork on d7. In fact, the one line where I don't see a smashing win is 24.Nf6, Qa7; (protecting f7 again, so the mate is prevented); however, White can at least win a Pawn with 25.NxN/d5 and 26.QxP.
Time to fire up Fritz.
|Aug-07-09|| ||jheiner: I wasn't going to post since Nf6 is clearly superior, but here are more amusing continuations from my 24.Ng5 train of thought. (24...hxg5 and 24...f6 were in previous posts.)|
24.Ng5 Kg8? (Now the g7 pawn will be pinned when the N moves)
25.Nxe5 (Forking the Rf8 and threatening mate via 26.Rxg7+ Kh8 27.Qxh6#.)
A.) Offering the R
26.Qxh6 (threatens 27.Qg7# so 26...fxe5
27.Qxg6+ K moves 28.Qg7#)
B.) Weakening g6 is inevitable.
26.Qxh6 (and while B has) Qa7
27.Qh5 (with the slow but inevitable 28.Rh3 and 29.Qh8#)
I believe this is correct. Haven't checked with Fritz.
But my point from the first post still stands that while this MAY be winning, there was a much better move on the board in 25.Nf6.
If this were a clear win, then maybe I could skate by and take credit, but in this case no dice. Object lesson. Hope this helps others.
|Aug-07-09|| ||KastelFhlor: < YetAnotherAmateur: <jheiner> It looks to me like in the case of 24. Ng5 f6
is a decent response for black. A continuation might look like this: 25. Nf7+ Kg8
26. Qxh6 Rxf7
27. Nxf7 Kxf7 (else drop the knight without much to show for it) 28. Qxg7+ Ke8
29. Qg6+ Kd7
30. Qf7+ Kc6
31. Rc1+ Bc4
and the key thing about this is that while black's kingside has collapsed the black king has reached relative safety over on the other side of the board, and has even managed some level of counterplay with Rxb2 followed by an a-pawn push. >
Instead of 28 Qxg7+ why not 28 RXg7+ and 29 Qh8#?
|Aug-07-09|| ||KastelFhlor: Sorry! I did not se <jheiner> post!|
|Aug-07-09|| ||CHESSTTCAMPS: Well, having gotten stuck on the defense 24... Qd8, I've looked at the kibitzing already. FWIW, this is what I had written before this:|
Black has bishop for a knight and material is otherwise identical. Black is focused on the queenside (to the extent of abandoning kingside defense) and threatens Rxb2. White has a powerful K-side attack, with knights, Qd2, and Rg3 all well-placed. Each of black's k-side pawns are defended only once, suggesting that any of these targets is vulnerable, especially h6. My first impression was that 24.Ng5 was the right approach, but within 3 minutes I noticed something sharper.
At first glance this does not look forcing, but it is:
A) 24... Rxb2 25.Nxf7+ Rxf7 26.Qxh6+ gxh6 27.Rg8#
B) 24... gxf6 25.Qxh6#
C) 24... Nxf6 25.exf6 Rg8 26.Rxg7! Rxg7 (else Qxh6#) 27.Qxh6+ Rh7 28.Qf8#
C.1) 25... Qxd6 26.Qxd6
C.2) 25... g6 26.Qxh6+
D) 24... Nf4 25.Nd7 Qd8 26.Nxf8 Qxf8 27.Ra3 and white doubles rooks to win black's a-pawn (and create back rank threats) in addition to the exchange.
E) 24...Rf4 25.Nxd5 followed by Qxf4
F) 24... Qd8 25.Nh5 (25.Nxd5 exd5 26.Qxd5 Kh7 is less convincing) Qh4 26.Rh3! (Nxg7? Qf4) Qg4 27.Nf6! Nxf6 (Qg6 28.Rg3 traps the queen)
Here I stopped the analysis, not satisfied with line F. Few if any seem to have addressed 24... Qd8. <Shyfe> wrote <I was very concerned with 24...Qd8 until I saw 25 Rh3 which immediately ends the game...>
After 25.Rh3 (which I looked at), what about 25... Nf4? That attacks the Rh3 and blocks the sac on h6. Does anyone have a convincing finish? The Rybka line that <JimFromProvidence> gives against 24...Qa7 doesn't work in this similar position. At this point I have not consulted an engine...
|Aug-07-09|| ||wals: The following may be of help to those wanting help.
[Event "European Clubs Cup (Men)"]
[Site "Rethymnon GRE"]
[White "Boris Avrukh"]
[Black "Sergei Rublevsky"]
[Annotator "Rybka 3 1-cpu (30m)"]
D27: ueen's Gambit Accepted: Classical main line: 7 e4!? and 7 a4
1. d4 d5
2. c4 dxc4 3. e3 e6 4. Bxc4 c5 5. Nf3 a6 6. O-O Nf6 7. Bd3 Nbd7 8. Re1 b5 9. a4
bxa4 10. e4 cxd4 11. e5 Nd5 12. Rxa4 Bb4 13. Bd2 Bxd2 14. Nbxd2 (14. Nfxd2 Nc5 15. Rxd4 Nxd3 16. Rxd3 O-O
) 14... Nc5 lack threatens to win material: c5xd3 15. Rxd4 (15. Bb5+ Bd7
16. Bxd7+ Nxd7 17. Rxd4 O-O ) 15... Nxd3 16. Rxd3 O-O lack castles and
improves king safety (16... Bd7 17. Ne4 O-O 18. Qd2 ) 17. Nc4 (17. Ne4 Bd7
) 17... a5 (17... Rb8 18. Rd4 ) 18. Ra3 (18. Nd6 Rb8 19. Qc1 Qb6 )
18... Ba6 19. Nd6 An ideal square for the white knight. (19. Nxa5 Nb4 )
19... Rb8 lack threatens to win material: b8xb2 (19... f6 20. Ne4 ) 20.
Qd2 White threatens to win material: d2xa5 (20. b3 f6 ) 20... Rb4 The
black rook is well posted. 21. Ng5 (21. Re4 Qb6 22. Rxb4 axb4 ) 21... h6
lack threatens to win material: h6xg5 (21... Qb6 22. Qc2 g6 23. b3 ) 22.
Nge4 Qb6 23. Rg3 Kh8 (23... Qd4 the only rescuing move 24. Qxd4
Rxd4 ) 24. Nf6 Deflection: h6 Nf4 (24... Nxf6 25. exf6 Combination
) (24... gxf6 25. Xgxh6 Deflection (25. Qxh6+ Mate attack)) (24... -- 25.
Nxf7+ Mate threat) 25. Nd7 Rd4 (25... Qd8 26. Nxf8 Qxf8 27. Rf3 ) 26. Qxf4
(26. Nxb6 is clearly weaker Rxd2 27. Ra3 Rb8 ) 26... Rxf4 27. Nxb6 Rb8 28.
Nd7 Rxb2 29. Nc5 Bb5 30. Rf3 (30. Ra1 seems even better) 30... Rfb4
simply worsens the situation (30... Rxf3 31. gxf3 Kg8 ) 31. h3 Bc6
(31... a4 is not much help 32. Nxf7+ (32. Rxf7 a3 33. Kh2 a2 ) 32...
Kg8 33. Nd8 ) 32. Rxf7 a4 (32... Bd5 a fruitless try to alter the course
of the game 33. Ra1 Ba2 34. Ra7 ) 33. Nd3 (33. Nd3 Rb1 34. Nxb4 Rxe1+ 35.
Kh2 ) 1-0
|Aug-07-09|| ||SamAtoms1980: I found 24 Nf6, seeing that 24 ... gxf6 would run into 25 Qxh6 mate, that 24 ... Nxf6 25 exf6 would be nothing good for Black, and that White was posing the threat of 25 Nxf7+! Rxf7 26 Qxh6+!! gxh6 27 Rg8 mate.|
Black's rejoinder 24 ... Nf4 took me aback, and somehow I overlooked 25 Nd7 and instead went with 25 Re4.
P.S. In response to 24 ... Qa7 I was planning 25 Qc2.
|Aug-07-09|| ||Jimfromprovidence: <CHESSTTCAMPS> <After 25.Rh3 (which I looked at), what about 25... Nf4? That attacks the Rh3 and blocks the sac on h6. Does anyone have a convincing finish?>|
After 24...Qd8 25 Rh3 Nf4, white has a nasty surprise 26 Nf7+, a forced mate.
click for larger view
It seems like the black queen cannot find a good square anywhere on the board after 24 Nf6.
|Aug-07-09|| ||johnlspouge: Friday (Difficult):
B Avrukh vs Rublevsky, 2003 (24.?)
White to play and win.
Material: N for B. The Black Kh8 has 2 legal moves, g8 and h7, so a N at f6 could command both flight squares. The Black Nd5 defends f6, however. The White Rg3 x-rays g8 through Pg7, suggesting an Arabian mate. The White Qd2 can capture Ph3. Both White Nd6 and Ne5 are close to the Black K-position: Nd6 attacks Pf7, while Ne4 can play to f6 or g5. White has a local superiority in the Black K-field, suggesting the possibility of a sacrificial attack. Black threatens 24…Rxb2 and from there Pf2. The White Kg1 is vulnerable to 24…Qxf2+, presently a harmless check.
Candidates (24.): Qxh6+, Rxg7, Nf6
24.Nf6 (threatening 25.Qxh6+ gxh6 26.Nxf7+ Rxf7 27.Rg8#)
White has a secondary threat 25.Nd7, forking Qb6 and Rf8, which presently fails to the counter-attack 24…Rxb2, because the Black Nd5 controls the flight squares from which Qd2 can protect Pf2.
Black has no counter-attack against the White K, so he must defend directly.
(1) Black can capture Nf6:
24…Nxf6 [gxf6 25.Qxh6#]
25.exf6 (threatening 26.fxg7+ 27.gxf8=Q+)
25…g5 [g6 26.Qxh6+ Kg8 27.Qg7#] [Rg8 26.Nxf7+] [else, drop a critical P]
26.Rh3 (threatening 27.Rxh6+ 28.Qxg5#)
26…Kh7 27.Qc2+ (threatening 28.Rxh6 29.Qh7#)
Black has no defense.
(2) Black can protect Ph6, but the secondary threat limits his responses:
24…g5 [Rf4 or Rh4 or Nf4 25.Nd7]
25.Rh3 Kg7 26.Nde8+ Kg6 [else, Rxe8 drops R for N]
27.Qc2+ Bd3 28.Qxd3+ Re4 29.Qxe4#
(3) The Black Qb6 can fortify Pf7, to avoid deflection of the burdened Rf8:
24…Qa7 [Qc7 25.Nfe8 (forking Qc7 and Pg7 wins)]
25.Nfe8 g5 [Rg8 26.Rxg7 Rxg7 27.Qxh6 mates] 26.Rh3
White wins Ph6, hopelessly compromising the Black K-side.
|Aug-07-09|| ||OBIT: At first glance there are several candidate moves. After several minutes of thought, however, it seems to me the only move that makes any sense is 24. Nf6. Obviously Black can't play 24...gxf6?? 25. Qxh6#, while after 24...Nxf6 25. exf6 Black is surely dead because (a) the f-pawn can't be taken, (b) the g-pawn can't be pushed, and (c) the g pawn can't stay where it is. Some relevant lines are 25...g5 26. Rxg5; 25...Rg8 26. Nxf7+ Kh7 27. Rxg7+ Rxg7 28. Qxh6+ and mates; 25...Rd8 26. Rxg7 threatens Nxf7# and Qxh6#; 25...Rd4 26. fxg7+ Kg8 27. gxf8=Q+ Kxf8 28. Qxh6+, and White is up a rook. |
I also see that the threat after 24. Nf6 is 25. Nxf7+ Rxf7 26. Qxh6+ gxh6 27. Rg8#. Black can stop the mate by guarding the f-pawn or h-pawn on move 24, and it looks like there are three moves to do this: 24...Qc7, 24...Qa7 and 24...Rh4. To be honest, though, this is as far as I'd take the analysis in an OTB game. Now I'm moving 24. Nf6 and thinking about these three moves on my opponent's clock. (Hmm, after 24...Qc7, maybe 25. Nfe8 is good....)
|Aug-07-09|| ||OBIT: And so, my opponent plays 24...Nf4, and I say to myself "Hmm, that's one reply I never considered." But then I think that forking the queen and rook can't be bad. So I play 25. Nd7 without thinking too long, and I wait to see what else my opponent has planned. :)|
|Aug-07-09|| ||WhiteRook48: 24 Qxh6+ was my solution, 24...gxh6 25 Nf6 threatening 26 Nxf7+ Rxf7 27 Rg8# Arabian Mate
evidently it doesn't work|
|Aug-07-09|| ||OBIT: <WhiteRook48>Yep, it's refuted by 25...Nxf6. It's not Monday. :)|
Looking at 24. Nf6 Qc7, the cleanest solution is 25. Rxg7. With the threats Rh7# and Qxh6#, Black has to take the rook, but after 25...Kxg7 26. Nde8+ Rxe8 (forced to stop mate) 27. Nxe8+, and, after the exchanging is done, White will be up a queen for a minor piece. Equally good, actually, is 25. Nde8, since 25...Rxe8 26. Rxg7! transposes to the 25. Rxg7 win, while 25...Qe7 26. Rxg7 still mates. On the other hand, 25. Nfe8 can be considered inferior because 25...Qe7 26. Rxg7 Qh4 still requires some work.
IMO, the best defense is 24...Qa7. You folks with computers say the metal monsters analyze it to a win, eh?
|Aug-07-09|| ||CHESSTTCAMPS: <After 24...Qd8 25 Rh3 Nf4, white has a nasty surprise 26 Nf7+, a forced mate.> |
OK thanks - easy enough, but I missed it. Good old Krogius chess blindness.
|Aug-08-09|| ||LIFE Master AJ: I was working on (briefly) analyzing the whole game. I have not finished it, however, I think I do have a fairly thorough analysis of some of Black's alternatives on move 24.|
|Aug-08-09|| ||LIFE Master AJ: GM Boris Avrukh (2557) -
Rublevsky,Sergei (2672) [D27]
The 19th European Cup (EU-Cup)
Rethymnon, (R#6); Greece / 03,10,2003.
We have now arrived at the position for CG's daily puzzle / POTD.
click for larger view
For the moment, Black's King appears to be OK ... how does White defend his QNP in this position?
A brilliant shot ... that wins in all lines.
[Or </= 24.Rb1?! Rd4!; 25.Rb3!; is unclear. "~"]
According to Fritz, this is forced.
Here (below) I shall attempt to analyze all of the alternatives. I did this initially with Fritz 11, ran it by Rybka, then went over it again with Junior 10.1. (AND ... in a few cases ... I then went back to Fritz 11. Of course, all of this analysis was done under the ChessBase 10 interface, and I never used less than 750 MB of RAM for the HT.)
[</= 24...Rxb2?; 25.Qxh6+!! gxh6; 26.Nxf7+! Rxf7; 27.Rg8#.
Interesting was 24...Qb8; however it too was insufficient for saving Black.
Normally, you do not exchange pieces when attacking, this move is a violation of that rule. (Additionally, the folllow-up is very brilliant, and had to be carefully calculated as well.)
25...exd5; 26.Rxg7! Rh4T; Forced. ("" or "box.")
<(</= 26...Kxg7?!; 27.Nf5+! Kg6; 28.Qxh6+! Kxf5; 29.Qf6+ Kg4; 30.Re3! Qd8; 31.Rg3+ Kh5; 32.Rg5+ Kh4; 33.Qh6#.)>
27.Rxf7 Rxf7; 28.Nxf7+ Kg7; 29.Nd6, (White is "+ 2" in buttons.).
This was the defense that stumped me when analyzing only from the diagram, or just from memory.
The box shows this as best.
<(RR </= 25...Qe7?!; 26.Nxd5 exd5; 27.Nf5,
Or 25...Rbb8?; 26.Rxg7! Kxg7; 27.Rg4+, & mate next move.)>
26.Ndxe4 Ne7; Best - Fritz 11.
<(</= 26...Rc8!?; 27.Qg5!!, )>
27.Nh5 g5; 28.Nhf6 Rb8; 29.Rh3 Kg7; 30.Rxh6!,
(Fritz shows a mate in 9!)]
Now a simple Knight fork decides this contest (in White's favor).
25.Nd7 Rd4; (Forced.)
Black has to try something tricky in this position, otherwise he just loses the exchange.
[</= 25...Rxb2??; 26.Qxf4, ]
26.Qxf4! Rxf4; 27.Nxb6 Rb8;
Black could resign, White is a a piece ahead.
28.Nd7 Rxb2; 29.Nc5 Bb5; 30.Rf3,
White offers to swap Rooks, but as Black is down material, he has
to avoid exchanges.
[Maybe (better was) 30.h3!?, - Fritz 11.]
30...Rfb4; 31.h3 Bc6; 32.Rxf7 a4!?; 33.Nd3 ,
As Black is now forced to exchange to avoid further material losses ...
(Black must now play 33...Rb1; or lose an exchange as well.); he resigns, rather than continue.
|Aug-08-09|| ||LIFE Master AJ: My analysis ... as far as I can tell ... differs at least a little (in some cases, a whole lot!); than what has already been posted. |
So I offer it up for you to enjoy. (Maybe you can find something that I missed?!?!)
|Aug-08-09|| ||kevin86: The puzzle was above my paygrade,but the rook foek at the end was fun...|
|Aug-09-09|| ||LIFE Master AJ: <kevin86> It was not a real fork, Black could play 33...b1; when the (other) Black Rook is off limits. (34.x/b4??, x/e1+; etc.) |
Black resigned because he was being forced to trade material in a position where he was down.
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