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| Apr-27-10 | | johnlspouge: Tuesday (Easy)
Shaobin vs Koneru, 2005 (28...?) Black to play and win.
Material: Even. The White Kf1 has 4 legal moves. Most ominously, the Black Ba6 x-rays Kf1 through the Black Pd3, suggesting a clearance of Pd3. The White Qd2 blockades Pd3, while providing the sole support of Bc3. Thus, examination of the candidate 28…Qxc3, deflecting Qd2, is mandatory. The Black Kg8 is vulnerable only to Be4-h7+. Candidates (28...): Qxc3
28…Qxc3 29.Qxc3 [else, drop Bc3]
29…d7+ 30.Kg2 [or Kg1] [Kf2 d8=N+ 31.K any Nxc3 leaves White with B+N for P] 30.d8=Q
White has B for P. Black has positional superiority, as well, because of the open White K. |
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| Apr-27-10 | | Once: <dzechiel> It's not so much the mate in 13 - it's more that white will have to throw his queen very quickly to stave off a faster mate. Here's the position after 30...d1=Q.
click for larger viewHow is white going to stop 31...Bc5+ 32. Kg2 Qf1# or 31...Qe2+ 32. Kg1 Qf1#? A move like 31. Bd3 simply delays the mate by one move with 31...Bxd3. In the next move or so, white is going to have to give up his queen for one of the black bishops. I suppose it comes down to time and pragmatism. If time was very short, then I would undoubtedly play 30...d1=N+ in a heartbeat. It wins. But does it win cleanly? White would be two pieces down, but he might harbour hopes of setting up a fortress. Minor piece endings can be tricky. Given a little more time, I would look at 30...d1=Q and the mate threat. After all, white might play on a couple of minor pieces down, but he would surely throw in the towel if he was a whole queen down. Both moves win, and either counts as a solution today. |
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| Apr-27-10 | | johnlspouge: < <dzechiel> wrote: <Once: ... Now, the flashy 30....d1=N+ followed by 31...Nxc3 wins two pieces, but stronger still is the plain old 30...d1=Q: ...> Once (no pun intended) again we have the "what's the BEST move" question. [snip] > IMHO, the practical difference between mate in 13 and an evaluation of +8.0 P is nil: more profound improvements occur plumbing the puzzle depths on Saturday or Sunday than finding lengthy mates on Monday to Wednesday. On the other hand, if a gentleman like <Once> points out that I missed a mate-in-13, I will just slap my forehead and thank him! |
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| Apr-27-10 | | johnlspouge: < <Once> wrote : [snip] Both moves win, and either counts as a solution today. > With respect to my previous post, who says you do not get to know people over the Internet? :) |
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Apr-27-10
 | | tarek1: Obviously, Black wishes to remove the blockade on d2, which would allow a discovered check.
So <28...Qxc3>
wins a piece, because if White takes back <29.Qxc3> then <29...d2+>
if <30.Bd3> Black queens with check then takes on d3 with two pieces up. And if <30.Kf2> Now <30...d1Q> is ok, black is a piece up, but <30...d1N+> is even stronger :
<31.Ke1 Nxc3> Black is two pieces up. So <30.Kg2 d1Q> Black is a piece up. |
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| Apr-27-10 | | stacase: The discovered check should Black's d3 Pawn get a chance to advance sort of jumps out at you. |
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| Apr-27-10 | | agb2002: The material is even.
White threatens 29.Bxd3, although 29... Bb7 followed by ... Qc6, seizing the a8-h1 diagonal, would cause serious problems. The white king lies on the a6-f1 diagonal, controlled by Black's LSB. This suggests 28... Qxc3 29.Qxc3 (otherwise drops a bishop in a lost position) d2+: A) 30.Bd3 d1=Q+, winning the other bishop or quicker, finishing the game with a mate attack (... Bc5+ or ... Bb7+, etc.). B) 30.Kf2 d1=Q (threatening 31... Qe2+ 32.Kg1 Qf1#; 30... d1=N+ and 31... Nxc3 - + [B+N vs P] also wins easily) 31.g4 Bh4+ 32.Ke3 Qe2+ 33.Kd4 Bf2+ 34.Qe3 Bxe3#. C) 30.Kg2 d1=Q (threatening 31... Qf1#) 31.Qf3 (31.g4 Qe2+ 32.Kh3 Qxe4 - + [2B vs P]) Be2 32.Qf2 Bc5 - + [Q vs P]. |
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| Apr-27-10 | | agb2002: <Once: ...
But does it win cleanly? White would be two pieces down, but he might harbour hopes of setting up a fortress.> After ... g5 White can't defend the dark squares nor the pawns there because Black has a knight and the DSB. It would be a slow massacre. If White trades his bishop for the knight the bishops and the king would create mate nets quickly. |
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| Apr-27-10 | | gofer: This positions screams for a queen sacrifice that leaves white with very few alternatives
and all of them imply that white will finish the exchange at least a whole queen down or
get mated!
28 ... Qxc3
Option 1 (accept)
========
29 Qxc3 d2+
30 Kg2 d1=Q
White has no counter-attack as black's bishop is guarding c8. But black is now threatening 31 ... Qf1# and this is not possible
to block as black controls the a6-f1 and d1-h5 diagonals. If white attempts to blockade f1 with 31 Qf3, but 31 ... Be2 32 Qf2 Bc5
kills this plan, either winning the queen or mating with Qf1#. So the white king must run and running achieves nothing! 31 Kh3 Bf1+ 32 Bg2 Qh5#
White's most protacted defense is something like...
31 Bd3 Bxd3
32 Qc8+ Kh7
33 Qh8+ Kxh8
34 g4 Bf1+
35 Kg3 Qe2
36 g5 Qg2+
37 Kh4 Qh3#
Option 2 (refuse)
========
29 Ke1 Qd4
Threatening Qg1# and Qxe4 and Bb4 skewering the queen to the king!!! So white will resign! Time to check... |
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| Apr-27-10 | | David2009: Tuesday's puzzle Shaobin vs Koneru, 2005
28...Qxc3 picks up a Bishop. White has no counter-play since the Ba6 also guards c8. Time to check. |
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| Apr-27-10 | | whiteshark: <28...Qxc3> Shows the strength/danger of (the threat of) a discovered check. |
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| Apr-27-10 | | TheaN: Tuesday 27 April
<28....?>
Target: 1:25;000
Taken: 0:12;262
Material: =
Candidates: <[Qxc3]> -ML-
The only spectacular move in this dual Bishop endgame is the Queen sac to abuse the passed d-pawn, there is not much more to it. After: <28....Qxc3!> White does not really have any alternative than capturing the Queen. After 29.Ke1 Qxd2† 30.Kxd2 Bb4†  it's hard to say Black will not win easily. <29.Qxc3 d2†> the point, as this moves the passed pawn towards the promotion square with tempo. White may interpose or move the King, but White would want to avoid a check upon promotion: <30.Kg2> after 30.Kf2?, Black has simplification alternative 30....d1=N†! going two pieces up. Any other move allows d1=Q† with major troubles for White. Nonetheless: <30....d1=Q > it's hard to think of reasonable moves to block Qf1‡. c8 is covered by the Bishop, so counterattacks are out of the question, and White might as well throw in the towel. |
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| Apr-27-10 | | TheaN: 2/2
Interesting discussion about 28....Qxc3 29.Qxc3 d2† 30.Kf2 ?. To be honest, I didn't even look at the mating nets of the Queen and pieces, looking purely at material and simplification and see that d1=N† is an instant killer. That's why I agree with the assesment that d1=N† is best in time trouble, and d1=Q is the best move. And with time trouble I'm talking 3 to 5 minutes, not less than a minute as that is getting difficult anyways. |
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| Apr-27-10 | | amaurobius: Shouldn't this be Wu vs Koneru rather than Shaobin vs Koneru? I was one of those lazy people who didn't bother thinking beyond 28...Qxc3 29 Qxc3 d2+ |
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| Apr-27-10 | | wordfunph: 28...Qxc3 wins! |
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| Apr-27-10 | | vanytchouck: Easy to find, especially after following the 2nd game of the Anand - Topalov match where the same theme was latent. (...Ba7 ...Rxd3 ... e2+ ).
Anand has stopped any begining of hope with Rb3.
For the puzzle, is then :
28...Qxc3 29. Qxc3 d2 + and 30...d1 = Q winning. |
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| Apr-27-10 | | abuzic: In such positions it's very easy to play 28.Be4, trying to pressure on the advanced pawn but missing the combined Q sac folloewd by the discovered check and promotion into undefended square. Guarding the promotion square is better with 28.Bf3 or 28.Kf1, or getting the King out of the check with 28.Kg1 and the B can later go to either f1 or f3 (not 28.Kf2 when 28...Qc5+ leads to interesting variations) |
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| Apr-27-10 | | gtgloner: First thing that jumps out at me here is 28. ... Qxc3! Not sure if this is right, let's see.
_____________
Hah! Got it. |
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| Apr-27-10 | | thegoodanarchist: Got this in two seconds. An excellent Tuesday puzzle. Play might continue 29.Qxc3 d2+ 30.Kf2?? d1=N+!
On another topic, it is good that a young lady with the name "Humpy" did not grow up in the US - her school years would not have been too pleasant with all the teasing she would receive... |
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| Apr-27-10 | | A Karpov Fan: got it. nice again |
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| Apr-27-10 | | randomsac: Qxc3 works because a discovered check gives black his queen back for his advanced pawn. |
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| Apr-27-10 | | zanshin: <28....Qxc3> sort of jumps out at you. Best for White might have been <28.Bf3> to protect d1. |
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Apr-27-10
 | | chrisowen: After 28..Qxc3 white has a climb to mountain. The range is incorporate bishopa6 pd3 and affliate queening that hillside scrambler. The clandestine approach is passing up the buck 27..Bb7 and setting a trap with 28..Qc7. The method man is protect your neck Bf3 prevents the sac and keeps a lid on proceedings, then Ba6 cannot rake one of the channels. Wu tangles son alongside the lovely lady Humpy until black swarms and pockets deep Qxc3 killer. Be4 looks crap missing the point of it 0l. Rustle up a harder one next time. |
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| Apr-27-10 | | kevin86: Easy! I saw the loaded grenade in the bishop check-the pin was the pawn. To ignite,the pawn must be moved and first the queen forced to unblock it.Hence the queen sac-the pawn will check and then queen next move. Black is left a bishop ahead with the queen off the board+easy win. |
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Apr-27-10
| | doubledrooks: <Once> wrote: <But does it win cleanly? White would be two pieces down, but he might harbour hopes of setting up a fortress. Minor piece endings can be tricky.> I'm sure minor-piece endings can be tricky, but IMHO being two minor pieces up gives black a crushing advantage---he'll just munch on the white pawns, while always looking for an opportunity to exchange off white's last piece. |
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