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|Jun-26-11|| ||lost in space: This was the line in detail:
21...c3 22. bxc3
(22. Rd4 Rxb2 23. Qxa6 Nc6 24. Rc4 Nb4; advantage Black)
22...Nc4 23. Qd3 Nxd2 24. Bxd2 Qb8 25. Bb3 and also here I think Black has a significant advantage.
click for larger view
|Jun-26-11|| ||scormus: Spent ages lookig for a win for W (and wondered why I could even find a threat) before I saw "B to play". And I was sure the opening was Dragon-Yugoslav with the B b-pawn finding its way to c4. Not a good start.|
I'm sure it is not the best defense by W but I cant resist posting the following line. After 22 Kxb2 I dont see how W can escape, B's moves almost play themselves
21 ... Rxb2 22 Kxb2 Nd3+ 23 Kb1 Qb8+ 24 Qxb8 Rxb8+ 25 Bb3 cxb3 26 Rxd3 bxa2+ 27 Kc2 Rb2+ 28 Kd1 a1=Q+ 29 Bc1 Bh6 30 Rc3 Rd2+ 31 Ke1 Qxc3 32 Bxd2 Qxd2+ 33 Kf1 Be3 0-1
I suppose I'd better check the game ....
Hmmm .... W wisely decided against 22 Kxb2. Qxa6 looks better and I'd have had a hard time finding JM's continuation. Even if W had better moves the Nxf3-d2 manoever is very neat.
After 22 Kxb2 it seems B is better to force Qs off with Qb8+ than the more natural Qb5+
|Jun-26-11|| ||scormus: Ah, in my line I think 26 axb3 would have got W out of trouble. |
Just running it on Rybka now, who likes 21 Qc8. How boring of her, that lovely ++ didnt get a mention. As you say <Once> these Si engines are a hard headed bunch - theyre even more than some bank managers Ive known
|Jun-26-11|| ||sevenseaman: <scormus> <21 ... Rxb2 22 Kxb2 Nd3+ 23 Kb1 Qb8+ 24 Qxb8 Rxb8+ 25 Bb3 cxb3 26 Rxd3 bxa2+ 27 Kc2 Rb2+ 28 Kd1 a1=Q+ 29 Bc1 Bh6 30 Rc3 Rd2+ 31 Ke1 Qxc3 32 Bxd2 Qxd2+ 33 Kf1 Be3 0-1> |
Beautiful! Win or lose, it goes like Barcelona's short pass, flowing football. Enjoyed playing it through.
|Jun-26-11|| ||scormus: <sevenseaman:> thanks. even though the line is flawed, I still like it. |
I know what you mean about Barca ... magical!
|Jun-26-11|| ||bachbeet: Only move I saw was c3. This was definitely insane.|
|Jun-26-11|| ||JCRchess: 10.) O-O-O seems to be the wrong plan for White in this game. The White King appears to be safer on the King-side of the board.|
|Jun-26-11|| ||LIFE Master AJ: I thought for about 10 minutes ... and went for ...RxP/b2. |
However, I was nowhere near the game line.
|Jun-26-11|| ||Patriot: White threatens Qxa6, winning more material.
The move I want to play is 21...Rxb2 because it has some interesting responses if 22.Kxb2. 21...Nd3+ doesn't seem quite as strong here, and 21...c3 looks interesting but I will examine the capture first.
A) 22.Kxb2 Nd3+ -- If a check should be the first line examined, a double-check is even better.
A.1) 23.Ka3 Qb5 -- This threatens 24.Bb2# so any candidates for white must at least deal with this threat. The options seem to be Rb1, Bd4, e5, or Bb3. It is sometimes more efficient to examine what "could be" the best defense. This can help eliminate the entire line or step back and re-examine the previous candidate if your instinct is correct.
A.1.1) 24.Rb1 Bb2+ 25.Rxb2 Qxb2+ 26.Ka4 Qxa2+ 27.Qa3 Nb2+ 28.Kb4 Rb8+ wins the queen.
A.1.2) 24.Bd4 Qa5+ 25.Ba4 Qxd2 looks a little suspicious because of 26.Rd1. Maybe 26...Qxg2 in that line. I also looked at 24...Rd8? 25.Qxd8+ Bf8+ 26.Qxf8+ Kxf8 27.Bxd3 cxd3 which also looks wrong. How about 24...Bxd4 25.Qxd4 Qa5+ 26.Ba4 Qb4#? If 25.Bxd3 Qa5# or 25.Rxd3 Bb2#.
A.1.3) 24.Bb3 Qa5+ 25.Ba4 Qc3+ 26.Bb3 at the very least draws.
A.2) 23.Kb1 Qb5+ 24.Bb3 cxb3 25.Qxd3 bxa2+ 26.Kxa2
This last line makes me wonder if I'm missing something or if it is the line that refutes everything. Perhaps 24...Rb8 is the key but 25.Rxd3 cxd3 doesn't look so convincing for black.
Going back to 21...c3.
A) 22.bxc3 Nc4 23.Qd3 Nxd2 24.Qxd2 at least wins the exchange but is still behind materially.
I'm thinking 21...Rxb2 offers better winning chances but can't seem to work out the details. This is all I'm doing on this.
|Jun-26-11|| ||DarthStapler: I didn't get it|
|Jun-26-11|| ||agb2002: Black has a bishop and a knight for the bishop pair and one pawn.|
White threatens 22.Ba4 and 22.Qxa6.
The pawn on c4 avoids a knight fork. Therefore, 21... c4 22.bxc3 Nc4:
A) 23.Qf4 Nxd2 24.Bxd2 (24.Ba4 Nc4) Ra5 25.a4 and Black doesn't seem to have made much progress.
B) 23.Qxa6 Nxd2 24.Bxd2 (24.Ba4 Rb1+ 25.Kc2 (25.Kxd2 Qd8+ and 26... Rxh1) 25... Qb8) 24... Qb8 and White has three pawns for the exchange.
The convergence of three pieces and a pawn on b2 (the knight and the pawn after one move) and the first threat of White above suggest 21... Rxb2:
A) 22.Kxb2 Nd3+ 23.Kg1 (23.Ka3 Bb2#) 23... Qb5+ 24.Bb3 cxb3 25.Qxd3 bxa2+ 26.Kxa2 Qa4+ 27.Qa3 doesn't look very good for Black.
Instead of checking with the knight try with the pawn:
B) 22.Kxb2 c3+
B.1) 23.Kxc3 Nc4+ 24.Kxc4 Qb5#.
B.2) 23.Ka1 cxd2 24.Bd4 Nc4 25.Qc5 (25.Qd5 Ne3 26.Qc5 Bxd4+ 27.Qxd4
Nxc2+) 25... Qb5 26.Qxb5 Bxd4+ and 27... axb5.
B.3) 23.Kb1 cxd2 24.Qxd2 Nc4 25.Qe2 Qe5 followed by 26... Rd8 and the white king is in danger.
B.4) 23.Kc1 cxd2+ 24.Qxd2 Nc4 looks similar to B.3.
B.5) 23.Ka3 Nc4+ and 24... Nxd6.
B.6) 23.Kb3 cxd2 with many threats.
C) 22.Bd4 Rxa2 and Black is one pawn ahead with attack.
D) 22.Bb1 Rxb1+ 23.Kxb1 c3 24.Rc2 Nc4 with multiple threats.
|Jun-26-11|| ||DrMAL: Good answers and comments above (regurgitating engine output is lame), this puzzle is really about move order.|
21...Rxb2 or 21...Qc8 or 21...c3 are all winning and basically equivalent, the trick is to realize the necessity of playing correct move order afterwards.
With 21...Rxb2 22.Kxb2 the correct move is 22...c3+ right away then Qc8 ASAP. For example, after a move like 23.Kc1 (probably best) cxd2+ 24.Bxd2 Qc8 wins.
Similarly, with 21...Qc8 after white makes a move like 22.a4 (probably best) the correct move is 22...Rxb2 23.Kxb2 and then 23...c3+ right away wins.
21...c3 is a bit simpler but also a bit less effective. After 22.bxc3 (best) the correct move is simply 22...Qc8 winning.
In the game, white played 22.Qxa6 a mistake where 22...Qb8 wins faster. Beautiful tactical finish by GM Mestel!
|Jun-26-11|| ||morfishine: <sevenseaman> Well said and brings this all into perspective. I've wondered too the reasons for attempting to solve the POTD. There are so many angles since the outcome could be either side wins (no matter who moves first) or the game actually ended up drawn or lost but could've been won. Sometimes its hard to follow the right track. |
I agree completely with your reasons (2) & (3). The interaction with chess enthusiasts coupled with addressing the problem at hand are what makes the POTD unique. Its pointless to post "this should be a Monday Puzzle" or "this is not really insane". The puzzle is what it is: Find the best continuation that you can
You are correct sir. So no more acrimony: it leads nowhere.
Finally, I'd wish you would drop by at my forum more often. I enjoy your posts and comments.
|Jun-26-11|| ||wals: Rybka 4 x 64
22.Qa6, -3.62. Best, Kxb2, -2.08.
23.Qa3, -4.91. Best, Re1, Rf1, -3.62.
24...Nxf3, -3.62. Best, Ng4, -4.91.
25.Rd5, -12.69. Best, Rd3, -3.62.
25...Nd2, -6.36, second best. Best, Nd4, -12.69.
White resigned after 26. Bxd2, -6.36.
White's troubles started,
18.Qxd5, -0.91. Best, Bd4, -0.22.
|Jun-26-11|| ||Patriot: As much time as I spent on this, I'm disappointed in not seeing the very simple 21...Rxb2 22.Kxb2 Nd3+ 23.Ka3? Bb2#. This shows what happens when you miss a simple candidate (and a check!). I saw this after looking over <agb2002>'s analysis! And after going over this with Houdini, I missed several simple mates. It would be good to try to solve more "insane" problems like this to work out the bugs. Another lesson from my failure is instead of going that deep into the 21...Rxb2 22.Kxb2 Nd3+ line, it could have been more efficient to examine 22...c3+ at least within a few ply, although here I'm not so sure it would've helped.|
<agb2002> - Nice analysis by the way! I like the way you methodically examined each candidate.
|Jun-26-11|| ||Marmot PFL: 21...Rxb2 is too good to pass up - 22 Kxb2 c3+ 23 Kxc3 Nc4+ 24 Kxc4 Qb5 mate. Naturally white won't play like that, but if 23 Kc1 cd2+ recovers the rook and keeps the attack.|
|Jun-26-11|| ||WhiteRook48: i failed the puzzle completely. the only thing i came even close to getting was the c3 idea|
|Jun-26-11|| ||stst: Insane...quite many lines, like horse-racing, see if we pick a "long-shot!"
(A)N sac, Nd3+ ==> immediately gives B@g7 the likely blow of Bxb2+, but K can flee to right side...
(B)P sac, Pc3, gives chances of queening as well as Nc4 forking Q,R,B...
(C)Rxb2, R sac, exposing the K (K flee without taking is very unlikely!)
Since both (A) & (B) look more obvious, will take the "long-shot" (C):
21...Rxb2, IF K stays or flees to right, c3 to give Nc4 forks.
IF 22.Kxb2, Qb8+
24.Kc1 (Ka1 will be subject to B+) Nd3+
26.Rc2...keeping the pressure but...
|Jun-26-11|| ||stst: somehow mess up the order in the Rxb2 sequence:
Nd3+ (B+) as double + should come before Qb8+
|Jun-26-11|| ||sevenseaman: < Marmot PFL: 21...Rxb2 is too good to pass up> |
That about sums it up. Its too natural a sac to 'pass up' OTB. What deep analysis ends up doing is that it constrains or kills our instinctive reaction.
Most chess games have flaws-its a human interaction and emotions will always have a role.
Another similar reaction;
< Patriot: As much time as I spent on this, I'm disappointed in not seeing the very simple 21...Rxb2 22.Kxb2 Nd3+ 23.Ka3? Bb2#. This shows what happens when you miss a simple candidate (and a check!). I saw this after looking over <agb2002>'s analysis! And after going over this with Houdini, I missed several simple mates. >
Now, I am not trying to canvass support for Rb2. I am only saying we should not suppress our instincts. That will only come about if we learn not to get too embarrassed later, if they turn out or are painted to be wrong afterwards.
There is only so much time OTB and your natural inclinations and affinities are always going to have preponderance in your performance. Its another matter you work hard enough to make clinical analysis an integral part of your OTB presence.
Rare, but possible. That is when you tend to be a genius.
|Jun-26-11|| ||Patriot: <sevenseaman> That's a good point. OTB I wouldn't have nearly the time I spent on this problem and should probably trust my instinct on that. However it is also good to sharpen calculation skills. Not to calculate like a machine but become more efficient at calculation and pinpoint (and correct) the problem areas I tend to make. The real trick is to balance criticality with analysis and good time management.|
|Jun-27-11|| ||M.Hassan: "Insane" Black to play 21....?
Black is a pawn down
<23.Kxc3 could be disasrous for White:
23.....Nxf3+ 24.Kb3 Qb5+ 25.Ka3 Bb2#>
And Black is still a pawn down.
Time to check
|Jun-27-11|| ||tacticalmonster: candidate: 21 Rxb2
a) 22 Kxb2 Nd3+ 23 Kb1 Qb5+ 24 Bb3 cxb3 25 Qxd3 bxa2+ 26 Kxa2
b) 22 Kxb2 c3+! 23 Kc1 (23 Kxc3 Nc4+! 24 Kb3 Nxd6 25 Rxd6 Qb8+ 26 Rb6 Qe5 ) Nc4 24 Qc5 cxd2+ 25 Bxd2 Qe6 26 Qd5 Qc8- with Rd8 to follow
|Jun-27-11|| ||jheiner: 21. Black to play
Material: Black is down a P with N for B.
The Pa6 is en prise.
Black has substantial pressure around the White K on b2 and could increase that pressure.
The Black DSB on the long diagonal is particularly powerful.
In our wildest dream, would love to trade off the White DSB and begin an attack on the dark squares.
One observation is that if c4 were cleared, the White Q,R and B could be forked with a Nd4.
Candidates: Nd3+, c3
If 22.bxc3 Nd4 (23.Q moves, and Na3, Nxd2 and Nxe3 all look juicy)
If 22.Rd5 (Rd3 maybe) cxb2+ 23.Kb1 Nd4 (threatening Na3# looks juicy)
This seems pretty straightforward for a Sunday. Here's a guess at how the game continued.
21...c3 22.Rd4 (to keep the N out of c4)
22...cxb2+ 23.Kb1 (what else?)
23...Qc8 24.Bb3 (fighting for c4)
24....Rc5 (if 25.Kxb2?? Nd4+ double check wins the Q) and Black resigns soon
Time to check.
Wow. My line was totally different than the game continuation, but still feels ok. I think White is just sunk in this position.
<DrMAL> had some interesting points about various continuations. I looked at Qb8 and Qc8, but after trading off the DSB. Probably not the best idea. Great puzzle.
|Jun-27-11|| ||KingV93: <Once> Well that is not so bad I suppose though I'm not sure I could convert a +2.26 according to Fritz. He can be such a spoiler, finding ways out of great moves like 21...xb2 which work OTB. |
Brings to mind my favorite quote, one I employ as often as possible:
"A good sacrifice is one that is not necessarily sound, but one that leaves your opponent dazed and confused." --- Spielmann
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