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|May-08-08|| ||234: Wednesday puzzle <30. ...?> May-07-08 M Dutreeuw vs O Salmensuu, 2001|
|May-08-08|| ||WickedPawn: Missed the core of the combination: The pin of the e5 pawn...|
|May-08-08|| ||RandomVisitor: After the improvement 20.Rfd1
click for larger view
Rybka 2.3.2a 22-ply
1. (2.06): 20...exd5 21.cxd5 Qb7 22.exd6 Bxd6 23.Qe4+ Kd8 24.Bxc5 Bxc5+ 25.Nxc5 Qb5 26.Nd3 Qb6+ 27.Kh1 f5 28.Qe5 Ng4 29.Qxg7 Ne8 30.Qxh8 Rxd3 31.Rf1 Nf2+ 32.Rxf2 Qxf2
2. (2.03): 20...Qa6 21.exd6 Qxd6 22.Ng5 exd5 23.Qe2 Qa6 24.Bc1+ Be7 25.Re1 Ne6 26.cxd5 Qxe2 27.Rxe2 Ra4 28.dxe6 f6 29.Ne4 c4 30.Nbc5 Ra8 31.Nb7 Nf5
|May-08-08|| ||hedgeh0g: I couldn't see anything besides the long-term goal of creating two passed e and f-pawns. When I played through the answer though, I can't believe I didn't see it. A hard combination to find, but surprisingly simple once you know the solution.|
Perhaps Black would have been better off losing the exchange with 24...Kd8 25. Qxg7 Rxf8 26. Qxf8+
Unless I'm missing another combination which nets White even more material...
|May-08-08|| ||johnlspouge: Thursday (Medium): White to play and win.
Material: Up a P. At first glance, White has few resources beyond mere material superiority. In particular, his P majority on the K-side is less advanced than the Black Q-side P majority. His Kg1 is behind Ps, however, unlike the Black Ke8, which is in the center, vulnerable. The Black Ra3 pins Ng3 to Qd3; the Black Qb6 shares the a7-g1 diagonal with Pc5, Ne3, and Kg1; and the White Rf1 is on the same file as Pf4 and Nf8 (making the capture …Kxf8 precarious). Presumably, a capture has just occurred, because the moves Qxe3, …Kxf8, …Rxf8 and …Nxf1 are in the air. The most forcing move, 24.Qg6+, looks pointless, but a superficial sampling reveals some hidden resources, making the line worth examining.
Candidates (24.): Qg6+, f5
[else, 25.Qxg7, winning a P with positional superiority and more to come]
25.f5 (threatening 26.fxe6+ and 26.f6 then 27.fxg7 or 27.Qxg7)
The Qg6 pins Pe6 to Qb6, preventing …exf5. Black has several feasible options.
(1) 25…Kg1 26.f6 Rh7 27.f7+ Kf8 28.Qxh7 Nxf1 29.Rxf1
and Black can resign.
(2) 25…Nxf5 25.Rxf5+ Kg8
[25…Ke7 26.Qxg7+ 27.Qxh8+ picks up the Rh8 <with check>]
26.Qf7+ Kh7 27.Rh5#
(3) 25…Nxf1 26.f6 (threatening 27.Qxg7+ 28.Qe7#, and 27.fxg7+)
(3.1) 26…Rg8 [or Ne8] 27.Rxf1 (threatening 28.fxg7+)
White recovers the material with a raging attack.
(3.2) 26…gxf6 27.Qxf6+ Kg8 [else, 28.Qxh8] 28.Rxf1 and mate soon.
(4) 25…Rh3 26.fxe6+ Nxf1 27.Rxf1+ Kg8
[Ke7 28.Qf7+ 29.Qd7#]
29.Rf8+ Kxf8 30.Qf7#
|May-08-08|| ||Salaskan: Brilliant. I'd never have guessed it. It's not too often that you see a mating combination that exploits doubled pawns. I was looking at something with cxd5 to create two passed pawns.|
|May-08-08|| ||handle: I decided on f5 right out of the gate. Too bad.|
|May-08-08|| ||johnlspouge: <<zooter> wrote: I wonder what's wrong with... |
24.Qxe3 Rxf8 (24...Kxf8 meets with 25.Nxc5 Rxe3 26.Nd7 winning the queen back with a pawn) 25.Qxc5+ Qxc5 26.Nxc5 and white's lead has increased to 2 pawns and should be winning....>
There's nothing wrong with this line, but because Black wins Pc4, so there is no immediate gain in material.
Toga evaluates the initial position as about +1.05 Ps in White's favor. Under the usual conditions, Mom-and-Pop Toga II 1.3.1 analysis yields
[ply 15/60+, time 11:39, value +2.00]
24.<Qxe3> Rxf8 25.Qg3 Qc6 26.Qg6+ Kd8 27.Qxg7 Re8 28.cxd5 Nxd5 29.Rac1 c4 30.Rf2 Qb5 31.Qg5+ Kc8 32.Qg6 Nc3 33.Nd4 Qd7 34.Nc2 Rxa2 35.Nxb4
Toga evaluates the game line as
[ply 15/64, time 03:52, value +4.25]
24.<Qg6+> Kd8 25.Qxg7 Rxf8 26.Qxf8+ Ne8 27.Rf2 Nxc4 28.Rb1 Ne3 29.h3 Ra8 30.Nxc5 Rc8 31.Rc1 Nc4 32.Nd3 Qa7 33.Nxb4 Qe7 34.Qxe7+ Kxe7 35.g4 Ng7
I am starting to consider evaluation differences of 0.5 Ps a matter of computer opinion, whereas the values above show that 24.<Qg6+> is much better than 24.<Qxe3>. Both should win, however.
|May-08-08|| ||mikejaqua: I actually did find white's first two moves on this one. I did not see 26. fxe6+ though.|
|May-08-08|| ||cade: How does White win after the Black King takes the Rook on f8?|
|May-08-08|| ||mworld: great puzzle today CG.com!
Don't think i've encountered this type of rank pawn pin on a piece other than a king.
|May-08-08|| ||mworld: < cade: How does White win after the Black King takes the Rook on f8? >|
Qxf7# after KxRf8
|May-08-08|| ||DarthStapler: Didn't get it|
|May-08-08|| ||lost in space: Back from work, now with more time. Very complex situation, not easy to solve|
The first variant, not winning:
24. Qxe3 Rxf8 25. Qxc5 Qxc5+ 26. Nxc5 dxc4 27. Rfb1 Nd5 28. Nxe6 Rf7 =
My favorite: 24. Qg6+ Kxe8 (24... Kd8 25. Qxg7 Rxf8 26. Qxf8 Ne8 27. Qxc5 Qxc5 28 Nxc5 Nxf1 29. Kxf1 and Black is lost (in space)) 25. f5 Nxf1(25...Nxf5 26. Rxf5 exf5 27. Qxb6) 26. Rxf1 Ke7 27. Qxg7+ Kd8 28. Qxh8+ Kd7 29. fxe6 Kc6 30. e7 Kb7 31. Rf6 and Black is lost (in time)
I was nearly lost in space-time :-)
|May-08-08|| ||patzer2: For today's Thursday puzzle, White sacrifices his Knight for a decisive attack on Black's helpless King with 24. Qg6+!!|
See <johnlspouge>'s post of Toga II analysis above for a strong winning follow-up line., and also for an analysis of the "obvious winning" though slightly less strong 24. Qxe3 .
|May-08-08|| ||zb2cr: Bah. I overestimated Black's attack by the Knight at e3 on the White Rook on f1, so I didn't think of f5.|
|May-08-08|| ||kevin86: I answered this one is spirit,if not by actual moves-lol|
If white could remove his pawn from the f-file,the win would be easy;black's attack by the knight at e3 is meaningless as white can replace it by Rxf1. I didn't see the desperately obvious advancement of the pawn to f5. Blacks pawn is frozen and cannot avoid a white capture at e6.
Here is a strange case of a pawn,by its very existance,dooming its holder. Ironically,if not for the black pawn,white's pawn would spoil the attack for good.
|May-08-08|| ||YouRang: Foo. I just didn't think 25.f5 would be fast enough. And too lazy to make sure.|
I settled for 24.Qxe3 thinking that went into the endgame with an extra pawn, better pawn structure, and a stronger knight. (I didn't think it was THE solution, but it's probably what I would have played.)
|May-08-08|| ||Marmot PFL: This one is tricky because the Nf8 suggests some desparado tactics with white getting whatever he can for it. These don't lead anywhere though while Qg6+ forces the K to the f file (to defend g7), and pins the e pawn which is very important allowing the crushing f5. From there it's elementary for Watson with a rook thrown in to bring quick mate.|
|May-08-08|| ||Marmot PFL: A little off topic, I have had some good games with 5.f3 against the Benko but the line 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 a6 5.f3 e6 6.e4 c4!? 7.Bxc4 axb5 8.Bxb5 Bc5 is very hard to meet. Possibly 7.Nc3 is better than Bxc4 but still black is OK in a complicated game.|
|May-08-08|| ||lost in space: Had now a look to the game. Wow, very impressive. Would never ever play the opening like this, neither as White nor as Black (not according to my calm style)|
During solving the puzzle I was not thinking a second about 25...Rh6. Good for me, that it is not saving Black.
|May-08-08|| ||robinpark98: 27. Rf8+! Kxf8 28 Qf7#|
|May-08-08|| ||DavidD: A tactical position. Exact calculations of variations are required--no need for an extensive positional evaluation or comments on material. You must examine forcing moves, and the most forcing are checks and captures. Qg6+ is a good move to consider. After Kxf8, f5! is a really beautiful move because the e-pawn is pinned laterally. The move ...Nxf1 has no real significance because Rxf1 keeps a rook aimed at Black's king. After f5! the threats against Black's king look unanswerable. An interesting question to consider is when Watson saw Qg6+. I suggest he probably saw the entire combination at move 20, and that is indeed impressive. The sad fact is that the Benko Gambit is my favorite opening and it deserves a better handling than Black gave it here. Two lessons to remember: in tactical positions, calculate variations starting with checks and captures. And always, always, always, look at all the checks and captures in a position before moving.|
|May-08-08|| ||wals: Static Evaluation: White is up a pawn, otherwise material is even. Bishops are off the board.|
Dynamic Evaluation: White to move. What would be the best shot?
Qg6+, Kxf8, no advantage there.
Nxe6, Nxe6, f4-f5, Nxf5, Qxf5, Kd8
Nxe6, Qxe6, Nc5 loses the Queen for the Queen.
f4-f5, Rxf8, f5-f6, gxf6, Qg6+,
Really no idea who is going to do what to whom and when
24.f4-f5 ...Rxf8 25.f5-f6 ...gxf6 26.Qg6+...Kd8
So, old smart RRRZZSSS, says , no advantage there, looking for the quick fix. Bravo! Badly done.
John L Watson - Zakhar Fayvinov, World Op, Philadelphia 1993
Analysis by Fritz 11: depth 19/40 time 6min 25
1. (3.44): 24.Qg6+ Kxf8 25.f5 Nxf1 26.Rxf1 Ra8 27.fxe6+ Kg8 28.Qf7+ Kh7 29.Rf5 Qxe6 30.Rh5+ Qh6 31.Rxh6+ Kxh6 32.cxd5 Na6 33.Qf4+ Kg6 34.Qg3+ Kh7 35.d6 Rhd8 36.e6
2. (0.64): 24.Qxe3 dxc4 25.Qxc5 Qxc5+ 26.Nxc5 Rxf8 27.Rfb1 Rxf4 28.Rxb4 Ra5 29.g3 Rg4 30.Nb7 Rxe5 31.Nd6+ Ke7 32.Nxc4 Re2 33.a4 Rd4
|May-08-08|| ||znprdx: ok so the really ironic point is that if Black had played ...23.d5xc4 24. Qd7+ K x[N]f8 25.Bxc5+ wins the Queen. OUCH! Once again however I rejected the obvious because I didn't look deep enough...this is another very pretty theme! It is amazing that W@hite has all the time in the world to play f5|
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