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Later Kibitzing> |
| Nov-23-08 | | TheCap: My idea tonight was:
20. ... Nxc3
21. Qxc3 f4
which leads to some nice positonal possibilities for black; but not more unfortunately... |
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| Nov-23-08 | | peristilo: Is it possible for any human being to calculate all moves in this "puzzle"? It seems to me its rather a matter of intuition than calculation. I doubt black
saw all moves in advance! Thats the kind of position you can play and sacrifce something relying only on the positional advantage without burning your brains to see the final result! |
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| Nov-23-08 | | peristilo: I dont think this is a good a puzzle! |
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| Nov-23-08 | | peristilo: Even after white losing his queen the win for black is not clear, for material is still equal! |
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Nov-23-08
 | | chrisowen: O I learn that long castling with queens on board and a semi open b row is simply too swash-buckling thinks white. 20..Nxb2 and black whips up a nasty attack down it in buccaneering style. 21..Bf8 Nb1 Rb7 rebuilding the assalt looks like the correct follow-up. |
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| Nov-23-08 | | patzer2: For today's insanely difficult Sunday puzzle, Black plays the demolition 20...Nxb2!! with the decisive follow-up 21. Nxb2 Bf8! After 21...Bf8!, Black's plan of creating a strong pin after 22...Bxa3, followed by an attack on the castled White King position, creates decisive threats. Here's my computer-checked breakout:
<20...Nxb2!! 21.Nxb2 Bf8! 22. Nb1> After the surprise follow-up 21...Bf8!,
White has no good answer to the threat of ...Bxa3!
If 22. Nba4??, then 22...Bxa3+ 23. Nb2 Bxb2+  wins easily; If 22. Nca4, then Black wins after 22...Bxa3 23. Qc3 Bg4 24. Re1 (24. Rd3 Bb4 24... Qxf4+ 25. Kb1 (25. Qd2 Rxe1#) 25...Rxe1+ 26. Qxe1 Qxd4 27. c3 Qxa4 ; If 22. d5, then 22...Bxa3 23. Nb5 Bxb2+ 24. Kxb2 Red8 25. d6 Qb6 26. Qd4 cxb5 is sufficient. <22... Rb7 23. c4>
If 23. Ba6, then Black is winning after Rb6 24. f5 gxf5 25. Qxa5 Bh6+ 26. Nd2 Reb8 27. Bb5 cxb5 ; If 23. Bd3, then Black wins with 23...Reb8 24. c4 Bg4 25. Rde1 Qd7 26. h3 Rxb2 27. Qxb2 Rxb2 28. Kxb2 Qxd4+ 29. Kc2 Be6 . <23... Reb8 24. Bd3 Rxb2
25. Qxb2 Rxb2 26. Kxb2 Qxf4 27. Kc3 f5 28. g3 Qd6 29. Bc2 Bg7 30. Rhe1 c5> 0-1 With an exposed King and no way to avoid a three pawn material deficit, White resigns his hopeless position. For example, if 31. Bd3, then 31...Bxd4+ 32. Kd2 f4 33. Bc2 fxg3 34. hxg3 Qxg3 wins going away. |
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Nov-23-08
 | | Morten: Remarkable: Black smashes through white's defences and forces the king up to c3 - but does not give a single check. BTW, I did not solve this... |
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| Nov-23-08 | | ShivaBala: I got nowhere near this, but knew that black would sac its knight to open up the b-file. I guess long castling was a mistake by the king. After move 14, black has a battery attacking white's castled king but white has nothing to show for its development. |
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Nov-23-08
 | | Jimfromprovidence: I tried to find some alternative defense for white. It involves sacrificing the bishop in order to reposition/better protect the two knights. This is what I came up with.
23 Ba6 Rb6 24 Na4 Rxa6 25 Nc5 Rb6 26 Nc3 Reb8 27 Qe3.
click for larger viewBecause black's position still looks so daunting, I don't know if this position is ultimately salvageable. |
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| Nov-23-08 | | patzer2: <Jimfromprovidence> From your diagramed position above, looks like 27...Bf5  to with the idea of follow-up like ...Rb2 or ...Bxc5 should be enough for Black to scratch out a win. |
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| Nov-23-08 | | patzer2: One fascinating aspect of today's deep Sunday puzzle combination
is the subtlety of the two consecutive moves 21...Bf8! and 22...Rb2! White deals with the threats of 22...Bxa3 by playing 22. Nb1, but suddenly 22...Rb2! makes the defending Knight on b1 a pinned piece and a new target for Black's attack. Despite being a piece up, White can do nothing to stop Black's plan of doubling Rooks on the b-file and winning back the sacrificed material with an apparently decisive positional advantage. Another interesting theme of the combination is the interweaving of the pinning tactic as first a threat after both 21...Bf8! and 22...Rb2!, and finally as a decisive tactical blow after 30...c5! |
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Nov-23-08
 | | sleepyirv: A classic example of mind over matter- It seems White has an unbreakable wall of defenders but at the cost of giving Black a lot of attacking lanes. Black uses his knight as a crowbar. Now if I could only spot these things BEFORE I look at the solution... |
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| Nov-23-08 | | bullsbehad: So I ask this question hoping that someone knows... Can a GM really spot a resign 10 moves out in a position such as this? I tend to agree with Peristilo that the Knight sack was intutive vs. calculated. It would take some serious time to figure this out, let alone doing so under the clock and pressure of a timed tournament? |
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Nov-23-08
| | Jimfromprovidence: <patzer2> <From your diagramed position above, looks like 27...Bf5 to with the idea of follow-up like ...Rb2 or ...Bxc5 should be enough for Black to scratch out a win.> After 27…Bf5, white will attempt to fight on gamely with 28 Rhf1. If 28…Rb2, then 29 Rf2. 
click for larger viewIf 28…Bxc5, then 29 dxc5 Rb2 30 Rf2.
click for larger viewBlack still has more work to do.
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| Nov-23-08 | | johnlspouge: Sunday (Insane):
O Maiorov vs I Zakharevich, 1997 (20…?) Black to play and win.
Material: B for N+P. The White Kc1 has 1 legal move, on the same file as Rb8. Both Be6 and Bg7 aim at the White K position, and both Na4 and Rb8 attack Pb2, which burdens Kc1 and Nd3. The Black Re8 has an open file; it, Bg7, and Qc7 require activation. Candidates (20…): Nxb2
20…Nxb2 (threatening 21…Nxd1 or 21…Nc4)
21.Nxb2 Rxb2
White can accept the sacrifice:
(1) 22.Kxb2
Candidates (21…): Rb8+, Bf8
Because 21…Rb8+ 22.Nb5 permits White to close the b-file, the defense Nc3-b5 requires counter-measures. 22…Bf8, activating Bg7 and threatening
(A) 23…Bxa3+ 24.Kxa3 Qd6+ 25.Kb2 Qb4+ 26.Kc1 [Ka1 is worse] 26…Qa3+ 27.Kb1 Rb8+ 28.Nb5 [Bb5 Rxb5+ 29.Nxb5] Qa2+ 29.Kc1 Qa1# My candidate for the second move 21...Rxb2 commits too much material too fast. Nowadays, I sacrifice too readily, but at least the importance of activating Bg7 was apparent to me. Toga evaluates the result after a variant of <JimFromProvidence>'s variation 20...Nxb2 21.Nxb2 Bf8 22.Nb1 Rb7 23.Ba6 Rb6
as about -1 P for White: while not crushing, it is probably a winning advantage. |
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| Nov-23-08 | | johnlspouge: < <bullsbehad> wrote: [snip] I tend to agree with Peristilo that the Knight sack was intutive vs. calculated. > As someone who relies on calculation more than most, I am willing to speculate that most kibitzers on this site seriously underestimate the amount and speed of calculation a professional chessplayer is capable of. In the absence of a really decisive result under best play, however, the N sac was likely more intuitive than calculated. In practice, under time pressure on http://chess.emrald.net/, e.g., I notice that I play attractive candidate moves that calculation under the time constraints (approximately 10 secs) cannot eliminate as best. Probably, Black looked a few moves ahead to find out which position looked most attractive after 20...Nxb2 and planned 21...Bf8 as a feasible follow-up. |
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| Nov-23-08 | | neilmcmurdo: This is a very hard puzzle!
Nxb2 followed by Bf8 are logical attacking moves.
But it is a significant sacrifice, and 20. ... Nxc3 is straightforward and looks ok for black. This isn't a case where the conservative, second-best alternative to the sacrifice is so bad as to force the attacker's hand. So deep analysis is needed. I got to 26. ... Qxf4 in over the board analysis, but analysed it as unclear and not clearly better than 20 .. Nxc3. Obviously, if one moves the pieces forward to the 26th move then it's obvious it's winning for black - material is even(ish) but black has all the attacking options. But it's a tough call to judge that six moves deep! |
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| Nov-23-08 | | patzer2: <Jimfromprovidence> After 27...Bf5 28. Rhf1 Rb2 29. Rf2, perhaps 29...Qb6! with threats like 30. g4 Bxc2! 31. Rxc2 Bxc5 32. Na4 Rb1+ 33. Kd2 Bxd4 34. Nxb6 Bxe3+ 35. Kxe3 Rxd1 is sufficient. |
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| Nov-23-08 | | bullsbehad: Johnlspouge: Thank you for the analysis. Being new here, I have no means to estimate GM capabilities. I assume they are capable of caculating 5-7 moves out and have intuition/experience to help for several moves beyond that. I'd love to know for sure, and how fast they do it. These puzzles seem like a good start, aside from the time element. |
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| Nov-23-08 | | johnlspouge: < <bullsbehad> wrote: Johnlspouge: Being new here, I have no means to estimate GM capabilities. > Welcome to the neighborhood :)
I have no means to estimate GM capabilities in chess either, but I am happy to dispense a free opinion ;>) <Thank you for the analysis.> I recommend not moving the pieces while solving the puzzles, only after, when examining the solution. A little training on CG puzzles can do wonders for your board vision. |
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| Nov-23-08 | | johnlspouge: <bullsbehad>, I believe a kibitzer called <UdayanOwen> had the strongest board vision of any kibitzer I encountered on CG. You might be interested in a lengthy post he wrote, one of several of his on
Glucksberg vs Najdorf, 1929 (although the post I refer to should be obvious). He gave arguments that Najdorf calculated his combination 12 moves out, with several complicated side variations. Again, for what my opinion is worth, I find <UdayanOwen>'s arguments compelling. |
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| Nov-23-08 | | Danya: GM Zakharevich died in August 2008 |
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| Nov-23-08 | | PieterPriems: The first move wasn't difficult! It were all the others! Bf8 is quit nice. |
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| Nov-24-08 | | njchess: I actually found the solution as far as 26. ... Qxf4, which I deemed winning for Black no matter what White did. My other first move candidate was Nxc3, but that really led nowhere so Nxb2 became obvious. 21. ... Bf8, though not as obvious as the immediate Rb7 was stronger since 21. .. Rb7 22. Na5 Bf8 23. Ba6 and the attack stalls. After 22. .. Rb7, I did calculate alternatives for White's 23. c4 such as 23. Ba6 Rb6 24. f5 Bxf5 25. Bc4 Reb8 26. Bb3 Qb7 27. Qe3 Bh6! 28. Qxh6 Rxb3 etc., which was also bad for White. Other than that, the moves were forcing. In many ways, I found this easier than Saturday's puzzle. |
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| Nov-24-08 | | kevin86: Rooks! I don't need no stinkin' rooks!
The exchanges/sacs open up white's position to bias pieces and lead to quick victory for black. |
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Later Kibitzing> |
Kibitzing
sac: 20...Nxb2