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| Aug-05-09 | | Shyfe: 10 Bxb6 axb6 (cxb6 11 Nxb6) 11 Nxb6 Qd8 (cxb6 12 Bb5)
I saw this line quickly, and I believed white to be winning easily after 12 Nxa8. Sure enough, I plugged it into Fritz and 12 Nxa8 is +2.63. However, 12 e5 is +3.56 and 12 f3 is +2.77. Interesting... |
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Aug-05-09
 | | offramp: This is a puzzle? |
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| Aug-05-09 | | dzechiel: White to move (10?). Black is up a pawn. "Medium/Easy." There it is! I spent about a minute trying to make 10 Ne5 work, but finally decided that the solution probably laid in the a4-e8 diagonal. As soon as I focused my attention there, I spotted... 10 Bxb6
Removing a piece. Black must retake or go down a knight. 10...axb6
Of course (and as we shall see) taking with the c-pawn would allow 11 Bb5. 11 Nxb6
Picking up an immediate pawn, and forking the queen and rook. If black doesn't capture the knight, he will be down at least an exchange and a pawn. But if he tries to play 11...cxb6
then
12 Bb5
wins queen and pawn for two minor pieces. Time to check and see when Grekov resigned. |
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Aug-05-09
 | | Jimfromprovidence: Just a note to say that the combination does not work if you change the move order. 10 Nxb6 axb6 11 Bxb6 is met by 11...O-O-O, with an even game. 
click for larger view |
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| Aug-05-09 | | Blitzer11: Saw the a4-e8 diagonal immediately.
Needed to clear the knight out to get the bishop to b5 but also eliminate the pawn on c6.First tried 10 Nxf6 followed by
11 Bb5 winning only a pawn (unless black plays 10 ...cxb6) then tried the order reversed
10 Bxb6 and 11 Nxf6
wins a pawn and atleast the exchange as capturing the knight allows Bb5! |
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| Aug-05-09 | | SamAtoms1980: <Q: I couldn't get the Wednesday puzzle this week. Are they getting harder?> A: No, you're getting worse. Time to cut back on those World of Warcraft excursions. [NOTE - I don't play WoW and never did, but I still didn't get this] |
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| Aug-05-09 | | Patriot: Initial candidates: Nxb6,Ne5,Bxb6
A) 10.Nxb6 axb6 11.Bxb6
Not very convincing.
B) 10.Ne5
And then? Maybe 10...Qc8 but not very clear.
C) 10.Bxb6 axb6 11.Nxb6 looks to be winning the exchange. 11...cxb6? 12.Bb5  So 10.Bxb6 is my choice. |
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| Aug-05-09 | | Sacsacmate: I tired with customary f7 square..but after a few seconds realized nothing is to happen there.
Then it struck me… 10 Bxb6 a/cxb6 11 Nb6 (exchange gain) if the knight is taken then Bb5 is curtains for black.
Even if black chooses to offer exchange white is up 1 pawn at least… slow death.
Time to check if I missed something. |
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Aug-05-09
 | | LIFE Master AJ: Sloppy (quick) analysis.
I saw the combo, but decided that either move order works. However as <Jimfromprovidence> has already pointed out, the only correct move order is: 10.BxN/b6; axb6; 11.NxP/b6, cxb6; 12.Bb5, when its time for Black to turn in his score-card. |
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| Aug-05-09 | | zooter: This looks more involved than the usual Wednesday stuff, but after 10.Bxb6 axb6 (or 10...cxb6) 11.Nxb6 wins the exchange as 11...cxb6 (or 11...axb6) 12.Bb5 wins the queen... Time to check |
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| Aug-05-09 | | zooter: I was also trying to make f7 work and an immediate Nxb6 work (for the b5 pin), but it doesn't work.... Also, had an unusual board vision failure when I decided 10.Nxb6 axb6 11.Bb5 c6 12.Nb6????? (that's when I saw the fork and remembered the knight is no longer available)...Then went back to move 10 and recalculated to get the correct solution |
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| Aug-05-09 | | remolino: 10.Bxb6 axb, 11. Nxb6 should do it. Time to check. |
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| Aug-05-09 | | lzromeu: I missed moving first the Knight
Obviously the fork on R and Q is stronger. |
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| Aug-05-09 | | TheBish: Bogoljubov vs Grekov, 1914 White to play (10.?) "Medium/Easy"
White is down a pawn, but has a slight lead in development (Black's kingside will take some time to develop) and White may be able to take advantage of the early development of Black's queen. Candidate moves: Ne5, e5, Nxb6, Bxb6
10. Ne5 Qd6 doesn't do much.
Same with 10. e5 Nd5.
10. Nxb6 axb6 (or 10...cxb6?? 11. Bb5 wins the queen) 11. Bxb6! wins a pawn (since 11...cxb6?? 12. Bb5 again wins the queen), but finding this led me to find a better move... 10. Bxb6! wins at least an exchange, since after either capture (10...axb6 or cxb6) 11. Nxb6! and the knight can't be captured, or White wins the queen (as seen before) with 12. Bb5. So, for example after 10...axb6 11. Nxb6! Qd8 12. Nxa8 Qxa8 and White has won an exchange plus his sacrificed pawn back. |
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| Aug-05-09 | | Summerfruit: Black is a pawn up.
The black queen and king are on the same diagonal suggesting a skewer.
At the moment it can be stopped by moving the pawn to c6. This possibility can be eliminated by: 10.Bxb6!
Black can take with either pawn, but to no avail.
10...axb6/cxb6 11.Nxb6! forking the rook and the queen. If 11...cxb6/axb6 12.Bb5 and the queen is lost. |
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| Aug-05-09 | | gofer: 10 Bxb6 axb6
11 Nxb6 Qd8 (cxb6 Bb5 winning the queen)
12 Nxa8 Qxa8
Time to check... |
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| Aug-05-09 | | agb2002: Black is a pawn up but is seriously behind in development. For example, the threat 10... Nxc4, trying to alleviate some pressure, seems to lose to 11.Qxb7 Rd8 (11... Nb6 12.Bxb6 Rd8 13.Bxc7; 11... Nxe3 12.Qxa8+ Qd8 13.Qxd8+ Kxd8 14.fxe3) 12.Bxc4 (threatening 13.Bb5) c6 13.Qxa7 + - (13... Nxe4 14.Qxd7+ Rxd7 15.Nxe4). The alignment of Black's royal family on a diagonal which can be accessed by White's LSB suggests 10.Bxb6: A) 10... axb6 11.Nxb6 Qd8 (11... cxb6 12.Bb5 + -) 12.Nxa8 + -. B) 10... cxb6 11.Nxb6 Qd8 (11... axb6 12.Bb5 + -) 12.Bb5+ Nd7 13.Bxd7+ Qxd7 14.Nxd7 Kxd7 15.Qb5+ and 16.Qxh5 + -. |
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| Aug-05-09 | | johnlspouge: Wednesday (Medium/Easy)
Bogoljubov vs Grekov, 1914 (10.?) White to play and win.
Material: Down a P. The Black Ke8 has 1 legal move. The Black K-side development lags. The Black K and Q are on the a4-e8 diagonal together, suggesting clearance of Nc4, to play Bf1-b5 pinning Qd7 to Ke8. The Black Pc7 is therefore burdened with the responsibility of Pc7-c6, to break the pin. The Black Nb6 is therefore guarded 1x and attacked 2x. The White Ke1 is vulnerable to Qd7-d1+, presently a pointless check. Candidates (10.): Bxb6
10.Bxb6 axb6 [cxb6 11.Bb5 wins Qd7]
11.Nxb6 (forking Ra8 and Qd7, threatening 12.Nxd7)
Black cannot counter-attack with any threat greater than the one to his Qd7, so he must defend the Qd7 directly. 11…Qd8 [cxb6 12.Bb5 wins Qd7] [else, lose R or Q outright] 12.Nxa8 Qxa8 White has R+P for B. |
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| Aug-05-09 | | johnlspouge: < <Jimfromprovidence> wrote: Just a note to say that the combination does not work if you change the move order. 10 Nxb6 axb6 11 Bxb6 is met by 11...O-O-O, with an even game. > Hi, <Jimfromprovidence>. Thanks for your insightful notes. I am curious as to why I did not even bother to consider the reversed move order. I believe that nowadays, I unconsciously decide which piece <remains> at the end of the capture sequence. There is no question that the Nb6, with its fork, is more threatening than Bb6, which in fact threatens nothing, other than the original pin Bf1-b5. |
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| Aug-05-09 | | lost in space: After looking for a few minutes to find out if 10. Ne5 is working if found the following sequence: 10. Bxb6 axb6
(10...cxb6 11. Bb5)
11. Nxb6 cxb6 12. Bb5 |
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| Aug-05-09 | | Patriot: <johnlspouge: ...I am curious as to why I did not even bother to consider the reversed move order. I believe that nowadays, I unconsciously decide which piece <remains> at the end of the capture sequence.> That is interesting. Usually it's correct to capture with the knight first over giving up the bishop pair. Plus the knight immediately forks queen and rook here so 10.Nxb6 must technically be more forcing. But I do remember looking at the position after 10.Nxb6 axb6 11.Bxb6 and thinking "It would be great to have a knight on b6 instead!" So then 10.Bxb6 became my "king of the hill" among the candidates. |
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| Aug-05-09 | | jsheedy: 10. Bxb6 wins a piece. If 10...axb6, 11. Nxb6, cxb6, 12. Bb5 wins the queen. |
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| Aug-05-09 | | patzer2: For today's Tuesday puzzle soluion, Bogoljubov's 10. Bxb6! neatly combines the deflection, decoy, clearance and Knight fork tactics to set up the threat of a decisive pin after 10...axb6 11. Nxb6 cxb6 12. Bb5! An interesting and instructive aspect of the combination to explore is the question of why 10. Nxb6 doesn't work as well. The reason is that after 10...axb6 11. Bxb6 White is no longer threatening to win the exchange as in the game continuation after 11. Nxb6, and Black has time to regroup and organize a defense. For example after 10. Nxb6 axb6 11. Bxb6 e5 (not 11... c6?? 12. Nb5! Rc8 13. f3 e5 14. Rd1 Qe7 15. Nd6+ ) 12. Be3 c6 13. f3  White has only a slight edge. |
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| Aug-05-09 | | whiteshark: White is winning a piece with 10.Bxb6.
10...axb6 11.Nxb6 cxb6 12.Bb5 makes it even more worse. |
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| Aug-05-09 | | patzer2: <Jimfromprovidence> Didn't initially consider your 10 Nxb6 axb6 11 Bxb6 O-O-O = to , but after looking it over I like it even better than 11...e5 12. Be3 . |
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