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| Dec-05-08 | | JG27Pyth: Yikes! As Dzechiel pointed out... LOTS of candidate moves... I decided on Bh6 and it was either Qxf6 or Ne5+ and I spent a long time trying to figure out which order to put them in, and which N checks at Nf5 and whether and when to recapture exf and ... arrrgh I'm just too dismayed by Rb7! Wha??? Nd3? *weeps openly* |
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| Dec-05-08 | | MaczynskiPratten: I find this one very difficult. I felt Bxh6 was the likely first move but after that it got too complicated. I didn't see 42 Nf3 and can't even see why Black is resigning, e.g. Nd6 brings his last piece into action. 43 Ng5+ Kh6 seems to hold for Black. I looked at 43 Nh5 gxh5 44 Ng5+ Kg8 and then couldn't see anything better than Qe6+ and Qxd7. What am I missing? |
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| Dec-05-08 | | dukesterdog2: I missed todays...went with 39. Rb7 to try to set up a pin on black's knight. I should have looked more carefully at 39. Bxh6 as it is more forcing. |
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Dec-05-08
 | | patzer2: For today's puzzle solution, White plays the demolition combination 39. Bxh6+!!, gaining two pawns for the piece and setting up decisive threats against the weakly protected King position. I must admit I found the position after 40...Rg8 41.Nhf5+ Nxf5 (as mentioned by <dzechiel>) to be difficult and confusing, but White's win became clear to me after seeing <ACCDrag>'s suggestion of 42. exf5! or his Fritz (computer) recommendation of 42.Nxf5+! Kh7 43.Rb7! (mating). |
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Dec-05-08
| | patzer2: <MaczynskiPratten> < can't even see why Black is resigning, e.g. Nd6 brings his last piece into action. 43 Ng5+ Kh6 seems to hold for Black. I looked at 43 Nh5 gxh5 44 Ng5+ Kg8 and then couldn't see anything better than Qe6+ and Qxd7. What am I missing?> Perhaps 43. Ng5+ Kh6 44. Ne6! is sufficient, when play might continue 44...Nef5 45. Nxf5+ Nxf5 46. Qf8+ Rg7 47. Rxc7 Qd6 48. Qxd6 Nxd6 49. Rxg7  . |
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| Dec-05-08 | | Eyal: <MaczynskiPratten: I didn't see 42 Nf3 and can't even see why Black is resigning, e.g. Nd6 brings his last piece into action. 43 Ng5+ Kh6 seems to hold for Black [...] What am I missing?> White has several ways to win here; for example, 44.Qf8+! Kxg5 45.h4+ Kxh4 (45...Kg4 46.f3+ Kxh4 47.Qh6#) 46.Qf6+ g5 47.Qh6+ Kg4 48.Qh5+ Kf4 49.Qxd1 followed by Qf3# |
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| Dec-05-08 | | johnlspouge: Friday (Difficult):
L Dominguez vs R Buhmann, 2008 (39.?) White to play and win.
Material: Even. The Black Kg7 has 3 legal moves. White has a local superiority on the Black K-position, with Qe6 covering light squares and both Ng3 and Nh4 able to reach dark squares after a move. The White Be3 reinforces the pressure on the dark squares in the Black K-position. Only the White Rb4 requires activation. Interestingly, Rb4 has access to the entire 4-th rank if Pe4 captures. The Black Bc7 is loose. The White Kh2 is secure, although it lies on the same diagonal as the Black Bc7, which might be dangerous if the Black Pe5 becomes mobile. Without an obvious candidate, an examination of checks, captures, and threats is next. Candidates (39.): Nhf5+, Ngf5+, Bxh6+, Nxg6
39.Bxh6+ Kxh6 [else, drop a P]
40.Qxf6 (threatening 41.Nhf5+ Nxf5 42.Nxf5+ Kh5 [Kh7 43.Qg7#] 43.Qh4#) (1) 40…Rg8 41.Nhf5+ Nxf5 42.Nxf5+ then 43.Qh4#
(2) 40…Kh7 41.Qf7+
(2.1) 41…Kh8 42.Nxg6+ Nxg6 43.Qxg6 (threatening 44.Nf5 45.Qg7#) White has 3Ps for (bad) B and an open Kh8. Black cannot force the exchange of Qs, so the entry of Rb4 into the K hunt via Rb4-b7 or Rb4-b3-g3 should decide the game. (2.2) 41…Kh6 42.Nxg6 (threatening 43.Nxe7)
42…Nxg6 43.Qg7 (threatening 44.h5+)
Black loses an excess of material to prevent mate. |
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| Dec-05-08 | | Eyal: Both 41.Rb7 and 42.Nf3 aren't easy to find - Rb7 demands a shift of attention to the Q-side, and Nf3 also requires some change of direction, since the natural tendency is to ponder sacs on f5. Btw, it's important to note that the Nf3-g5 idea only works after the black rook leaves the back rank; after 41.Nf3 Black can defend by 41...Kg8(!) 42.Ng5 Rf8. Instead of 41.Rb7, there's also a somewhat more "direct" winning procedure starting with Qf7+ or Nhf5, e.g. 41.Qf7+ Kh8 42.Nhf5 Rg8 (42...Nxf5 43.exf5) 43.Qf6+ Kh7 44.Qh4+; or 41...Kh6 42.Nhf5+ gxf5 43.exf5 e4 (43...Rd4 44.Qf8+ Kh7 45.f6) 44.Rxe4 Bxg3+ 45.fxg3 Rd6 46.f6. |
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| Dec-05-08 | | johnlspouge: I missed 41.Rb7.
The main problem today was the excess of candidates. It took a while to settle on 39.Bxh6+, rather than one of the N sacrifices. One might posit some general rules for selecting between candidates in a mating attack, as follows. (1) Because of their non-forcing nature, passive sacrifices like 39.Nxg6 generally require unusually rapid reinforcement by heavy pieces (usually Q) for success. (2) With only single control of the light squares around the K-position available, a successful mating attack must be based on spreading the attack to dark squares. Today, the rules make 39.Nxg6 less attractive than sacs with 39.Ngf5+ or 39.Nhf5+, and they make 39.Bxh6 more attractive. Unfortunately, the diffuse nature of the final attack is difficult to foresee, as <Eyal> points out, and to be sure of success, it seems difficult to avoid calculation. |
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| Dec-05-08 | | Eyal: <al wazir: I thought 39. Nhf5+ would win. I still do, e.g., 39...gxf5 40. Bxh6+ Kxh6 41. Qxf6+ Kh7 (41...Ng6 42. exf5, with Rh4 to follow) 42. Qf7+ Kh8 (42...Kh6 43. exf5, with Rh4+ to follow) 43. Nh5 Rg8 (44...Qxh6 45. Qxh6+ Kg8 46. exf5, with Rg4 to follow) 44. Nf6 Rg7 45. Qf8+ Ng8 46. Nxg8 Rxg8 47. Qh6#.> This line actually doesn't work, because instead of 46...Rxg8?? Black wins by 46...Qd8! However, White should be winning quite easily with 43.exf5 instead of Nh5. More challenging for White would be 39...Nxf5, where the Bxh6+ idea doesn't work after a knight exchange. 40.exf5 does win, however - but it requires again to find the Rb7 idea, e.g. after 40...e4 41.Rb7 Rd7/Qd7 42.Bf4. So 39.Nhf5+ is also winning, but not so simply.
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| Dec-05-08 | | Udit Narayan: can't wait to see this guy in action at corus 09!!! |
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| Dec-05-08 | | piever: I found 39. Nhf5 gxf5 40. Bxh6+ Kxh6 41. Qxf6+ Kh7 42. exf5 winning for white. I didn't spend much time on 39. ... Nxf5 because after 40. exf5 material is even but white has some threats on the seventh rank winning the bishop and it looks like black's kingside will quickly collaps. Anyway Dominguez preferred to play the usual winning bishop sac (which I think it's quite hard to calculate to the end, especially if it is just before the time control, but maybe he also relied on his instinct...) |
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| Dec-05-08 | | A.G. Argent: <Udit Narayan> I agree, he seems to be on the rise. Could be a bit of a dark horse at Corus. Cuban chess lives. |
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| Dec-05-08 | | zerowley: How are you guys doing these puzzles? Are you using a board, or doing it in your head? I can usually do Monday through Thursday in my head, but after that I usually need a board. I'm mainly doing these to improve my ability to calculate, so using a board kind of defeats the point. Any suggestions? I appreciate the analysis.
Thanks. |
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| Dec-05-08 | | MiCrooks: I came up with the Nhf5+ line rather than starting with Bxh6. It seems a bit more forcing as Black has to capture the Knight and then after gxf5 Bxh6+ leads to a clear crush. After the more talked about Nxf5 once again I don't see how Black hangs on. What many seemed to be missing was that the check you get from taking back with N is not worth much. You take back gxf5 instead which opens up a whole bunch of attacking avenues...black cannot block them all. If Black tries to block the rook's access to the 4th rank and limit the knights mobility by e4 then Rb7 wins by piling up on the Bishop combined with attacking the king. Other moves lose even more quickly. There are a number of tries but none seem to work (g5, h5, etc...) Not that Bxh6+ doesn't work immediately but I think it needs more foresight to play it. |
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| Dec-05-08 | | TheWizardfromHarlem: Chess games.com! why dont u start putting some defensive moves on these daily puzzles?? |
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| Dec-05-08 | | johnlspouge: Toga II 1.3.1 gives the following complete best-play variation, which humans can improve near the end. The last move I entered is <emphasized>: [ply 15/61 time 04:02 value +6.06]
38…<Ndc8> 39.Bxh6+ Kxh6 40.Qxf6 Kh7 41.Nhf5 gxf5 42.exf5 e4 43.Qf7+ Kh8 44.Rxe4 Nxf5 45.Qxf5 Qd7 46.Rh4+ Kg8 47.Rg4+ Qg7 48.Qe6+ Kf8 49.Rxg7 Kxg7 50.f4 Kf8 51.Qxc6 Bd6 52.h4 Ne7 [ply 17/70 time 12:13 value +5.51]
39.<Nxf5> Nxf5 40.exf5 e4 41.Bf4 Qd7 42.Rb7 Qxe6 43.fxe6 g5 44.Rxc7+ Kg6 45.h4 gxh4 46.Nxe4 Re8 47.Rxc6 Ne7 48.Rc4 Nd5 49.Nc5 Ra8 50.Bd6 My chessforum gives instructions on downloading freeware for chess analysis. |
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| Dec-05-08 | | veerar: Was lucky to spot the solution. |
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Dec-05-08
 | | al wazir: <eyal, eaglewing>: Thanks. These complications make my hair hurt. |
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| Dec-05-08 | | karoaper: I had it till move 40. Moving the rook to b7 didn't occur to me. |
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| Dec-05-08 | | karoaper: zerowley, you can move the pieces right in the java applet above. It's nice, because, it checks for validity of a moves.
I try to do as much as I can in my head, but then I need to move the pieces, because in my head I will forget some move and the position goes wrong. |
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| Dec-05-08 | | k.praneeth surya: first i have seen 39.nhf5 gf5 40.nh5 kg6 41.Qf6 kh5 42.Qh6# 40...kh7 41.Qf7 kh8 42.Qg7# 40...kh8 41.Qf6 kg8 42.Qg7# 40...kf8 41.bf6 ke8 42.nf6# 39...kh7 40.Qf7 kh8 41.Qg7# 39...kf8 40.bh6 ke8 41.ng7 kf8 42.nh5 ke8 43.nf6# but 39...move there is nf5 and 39.nh5 gh5 40.bh6 we must kill or elese matse 40...kh6 41.Qf6 kh7 42.nf3 and black must resign and afterwards i sawed another variation that is 39.bh6!and balsck must resign 39...kh6 40.Qf6 kh7 41.rb7 rd7 42.nf3 and black must resign ok.... |
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| Dec-05-08 | | njchess: I got this one right up to Nf3; I had Black resigning before that move since he has no counterplay. |
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Dec-05-08
 | | gawain: I think there are too many winning lines. I prefer that there be one winning line that stands out above all the others. I didn't solve it the way Dominguez did. I liked 39 Nhxf5+ and I still do. I think (even after much analysis) that it launches an overwhelming winning line after 39... Nxf5 40 exf5 (not Nxf5) that is just as compelling as the actual game line. Oh well. That's just a quibble.
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| Dec-06-08 | | Woody Wood Pusher: I missed 41.Rb7! Great move. |
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Kibitzing
sac: 39.Bxh6+