< Earlier Kibitzing · PAGE 4 OF 4 ·
|Dec-13-07|| ||mworld: i solved all the continuations in the bishop decline variation EXCEPT I never even thought of f6 - i'll give myself partial credit though, since the f6 variation is easy enough to deal with.|
|Dec-13-07|| ||MostlyAverageJoe: Factoid of the day:
The number of kibitzes on CG that contain the word "demolition": 544 (including this one).
The number of those kibitzes that were written by <patzer2>: 280
MAJ the statistician
|Dec-13-07|| ||JG27Pyth: <M-A-Joe: "ok, if black takes, then he gets mated, otherwise we have a pawn and there seem to be no counterattack, good enough." Personally, I am not satisfied with this, and don't consider it to be fully valid solution.>|
That's _exactly_ what I arrived at as well. I gave myself 80% credit (*generous, non?) In any sac situation you've got to consider the line if declined. (And if the sac is well calculated, it *should* be declined, shouldn't it?) I looked for a counterattack, which is just plain old chess due dilligence, but I failed to identify black's best defense (f5) and moreover failed to calculate the Bxg7 sac. I think full credit goes to anyone who calculated Bxg7 as a plausible continuation.
|Dec-13-07|| ||UdayanOwen: Hi all,
Can I say firstly how pleased I am that my post has stimulated such lively debate....
Jimfromprovidence -- If I have completely overstated white's advantage at move 20, I might be guilty of some bias... These kinds of positions, where one has space and co-ordinated piece play, against a disorganised and cramped enemy with several weaknesses are my absolute favourite to play - I find them very dreamy....
I don't have a lot of time to analyse the move 20...Nf6, since after my marathon session til sunrise, I have woken late and have to study today.... But superficially, it looks definitely like black's best chance for counterplay so hats off for the suggestion. In fact, after some brief analysis, I completely agree with you that 20...Nf6 is way better than 20...Bc7...
If white takes on d6, black can get the d pawn back quickly, and It frees up black's pieces and complicates the issue. On the other hand, 20...Bc7 defends d6 but allows white a free reign to win a pawn and exploit his positional superiority with either 21.Bxh6 or 21.Nb6. After 20...Nf6, if black takes on d6, black can get the d pawn back quickly, and blacks pieces are freer and he is complicating the issue:
20...Nf6 21.Nxd6 and now:
21...Qc7 I think is inferior, allowing 22.Nf5 Nxd5, when white's attack still looks extremely yummy (but black is not down a pawn this time and has better defensive and counterattacking chances than in the game).
21...Qd7, keeping the knight out of f5, seems to give black even better chances. 22.Nc4 Qxd5 (pinning the knight and thus preventing Nb6) and black seems to be getting very comfortable, with centralised pieces, material equality, the bishop coming out and the rooks having files.... After 21...Qd7, intuitively 22.Bc4 Nxd5 seems to still give white excellent play, but black is fighting here... I'm not going to analyze this position now, not yet at least, because there is a way to control the position after 20...Nf6 that should now be analysed because I suspect it will lead to a pretty cruisy queenside attack without much black counterplay...
Lets check it out... 20...Nf6, and I see three options to try and maintain a grip on the position:
21.Nb6 Bxb6 22.Rb6 (22.axb6 Qb7 looks OK for black) Nxd5 Rc1, when white will pick up the a pawn... he seems to have the edge but this seems playable for black
21.Qd3. or 21.Rd1. The idea is to control the position and create sustained play against black's queen side weaknesses (a6, d6 and the holes on b6 and c6), but admittedly, he will be slowed by the duty of holding his own d5 pawn... there are several options for black, and I don't have time to analyse them properly... I intend most likely to play Nb6, and if black plays Bxb6, to recapture with the rook, pressuring both a6 and d6... hopefully then I can maneuver a piece to c6 to increase the pressure... Strategically after either of these moves to defend the d pawn, white has a clear edge, and my analysis so far of various options by black all retain that clear edge with pressure that will be extremely hard to shake.... I still think the position is pretty dreamy, but I can't find a cruncher and black is hanging on for the moment (unlike in the game).
Well done for coming up with 20...Nf6.... Not only does it seem to retain material equality and create strong counterplay in many lines, but in the lines after 21.Qd3 or 21.Rd1, white has been slowed down and his play seems more limited to the queenside now. What I like about this move is its logic... In the puzzle position, black has so many problems that passive defence is sure to fail... 20...Nf6 centralises, gives the king a defender, and attacks white's only real target in this position, the d5 pawn.
|Dec-13-07|| ||al wazir: <RandomVisitor: After 21.Rc1> Thanks. I never considered 22. Nb6.|
|Dec-13-07|| ||GannonKnight: Good analysis. I did select 21. Bh6, but I feel better that I was unable to devise a forced winning plan. It just seemed like the move that was going to destroy a poorly defended king-side.|
|Dec-13-07|| ||apple pi: <MostlyAverageJoe>
How did you get that stat?!
|Dec-13-07|| ||MostlyAverageJoe: <apple pi: <MostlyAverageJoe> How did you get that stat?!>|
Go here: http://db.chessmetrics.com/CM2/Find...
Click on Hm
Click on Hmadi
Click "Event details"
Search for "Luzern" (Hmadi's ELO is right next to it).
Repeat the above for Nunn, or click on Luzern and look him up in the resulting page.
|Dec-14-07|| ||jperr75108: nice problem.|
|Dec-14-07|| ||UdayanOwen: Okay, so on the issue of whether one needs to calculate further if black doesn't take the bishop....|
I think there are two ways to classify a position as winning.... A strategically winning position, and one in which there is an absolutely forced sequence that leads to devastating material gain or checkmate. Obviously the second is better... Whites position is strategically winning after Bxh6, but there is no clear cut forcing win... But Nunn played it, and he analyzes the @#$% out of his games in post-mortem and this game has since been immortalized as a tactics puzzle... If a weakness in white's plan was found, I'm guessing it wouldn't make it as a puzzle, so lets assume it was the best move in the position... How can the puzzle not be solved after finding Bh6, but not the final position, when that final position was not completely forced? Or put another way, if Bxh6 is the best move, it has to be played on strategical grounds because there is no forcing win.... Who said a puzzle has to have a forcing variation? A puzzle, in the purest sense, is "find the best move", and in this position, that move wins a pawn, and strategically improves an already strategically overwhelming position.
I think that even strong players play on in strategically lost positions, because the onus is still on the opponent to prove it and not stuff up... I suspect that is why Hmadi played on, not because he seriously thought he had a chance against best play... The other reason he played on might have been that he would have known Nunn was most likely to sac on g7, after which at least Nunn has made a material investment, so even though he would have known he was dead against best play even after Bxg7, he still puts the onus on White to get it right. So I don't think the fact that black played on means that this position after 21.Bxh6 is not winning for white.
The question of when to analyze and when to draw strategical conclusions or make positional judgements is to a meaningful degree stylistic, in that chess players with different styles and ways of thinking will differ as to how they decide on their moves. If you want to analyze what happens if he doesn't take the bishop, its easy to work out that he has to play 21...f5 which is the only way to meet the threat of 22.Rg3 by 23...Rf7 without losing the exchange or creating a 'sea of cheese' after 21...Re8 22.Rg3 g6, when ideas like Qd4 and rook sac on g6, or h4-h5, don't need to be analyzed... one way or another, black's position will crumble.
So anyway, if it is your style to analyze after 21...f5, then go for it... I still think that the position is correctly solved without doing so.
I also think that the choice between 21.Bxh6 and 21.Nb6 is stylistic to an extent...Do you like to win a pawn and swarm all over a poorly defended enemy king, or do you like to occupy strategical strong points, win a pawn, stick a pawn on the seventh, and watch your opponent get squeezed to death? Both moves fit with the strategical character of the position by exploiting weaknesses in the enemy camp, and they both win material and improve already exceedingly strong positions.
Here is my reason for preferring Bxh6 over Nb6.... I think whites play on the kingside could be diminished soon if not Bxh6 now, because there is just one static weakness on h6, which will be hard to exploit if black gets some defenders over there. Personally I'd cash in on the kingside now before he can do that, because at worst you can retreat the bishop, say thanks for the pawn, and continue to play on the queenside, where the static weaknesses on a6, b6, c6 and d6 are not going away in a hurry. I do think the kingside attack will win with best play, and the reason I am happy to trust that intuitive judgement is because I CAN bug out with a pawn and a queenside attack if in the ensuing moves I think black is defending OK.
This post is continued in the next (ran out of space)
|Dec-14-07|| ||UdayanOwen: Finally, I hear what MostlyAverageJoe is saying that if you don't have very strong positional judgement, the tendency is to want to verify things with further analysis. What I am suggesting though, if one wants to get stronger, is not say, well I'm a bit weak with my strategical reasoning and positional judgement, so I'll just analyze further even though the position is not forcing. Instead, an alternative is to take the opportunity to start stretching oneself into developing these skills of strategical reasoning and positional judgement.|
Dvoretsky calls for this when he says combinational training should be a two-fold process, one where you calculate things exhaustively, and another where you think more thematically and find moves and trust your judgement without analyzing everything to the death. The latter is a critical skill, because at times, a strong sac will be available that cannot be analyzed to the end, but that 99 out of 100 GMs would play on positional grounds. Even more importantly, when analyzing you can rule out all kinds of sidelines and save clock time for more critical moments if you don't have to analyze every possibility down to the death.
To further defend my point of view here, I have a book "how to think in chess" which integrates a wealth of scientific studies examining the thought processes of strong players. In the introduction, the authors allude to the findings of De Groot, the pioneering and still towering figure in this area of research, who found that GMs typically do not analyze more or longer variations than the average player.
The authors the go on to give a couple of extremely dynamic sacraficial games with no analysis, followed by quotes by the winners. After beating Pilz in 1934, Najdorf said "this game was awarded the first brilliancy prize and nobody was more surprised than me since I can remember at no time seeing more than two moves ahead" Similarly, after smashing the great Tal in 1982, Nunn himself was quoted as saying "I hardly calculated a single variation more than a couple of moves deep during the entire course of the game".
Take it easy peoples... and bring on the debates :-)
|Dec-14-07|| ||whitebeach: Actually, after all the discussion, it seems to me that white could have played Bxh6 a move earlier--that is, instead of 20. Nc4, 20. Bxh6--and that it was probably just as strong then as on move 21, maybe even stronger, since black’s Q is still blocked by the B along the back rank and can’t give any help there, nor can the black K hope to escape via e8 and d8, plus white still has the move Ne4 available if needed. Black gets killed in all lines I see after 20. Bxh6. Am I missing something?|
|Dec-14-07|| ||MostlyAverageJoe: <UdayanOwen: an alternative is to take the opportunity to start stretching oneself into developing these skills of strategical reasoning and positional judgement.>|
Ah, but how do you validate your strategical/positional judgement stretches if not by additional analysis?
|Dec-14-07|| ||Jimfromprovidence: <whitebeach> <Actually, after all the discussion, it seems to me that white could have played Bxh6 a move earlier--that is, instead of 20. Nc4, 20. Bxh6--and that it was probably just as strong then as on move 21, maybe even stronger, since black’s Q is still blocked by the B along the back rank and can’t give any help there, nor can the black K hope to escape via e8 and d8, plus white still has the move Ne4 available if needed. Black gets killed in all lines I see after 20. Bxh6. Am I missing something?>|
That won’t work because black’s bishop will intervene.
If white plays 20 bxh6 then black will follow 20… gxh6. If white follows with 21 Qg4+ then 21…Bg5 blocks the attack.
|Dec-14-07|| ||al wazir: <UdayanOwen>: I agree with you. I've been whining for years that the calculations needed to analyze <CG>'s Sunday specials exhaustively are impossibly complex, and speculating -- only speculating! -- that GMs don't do the entire calculation, but rely on their intuition and experience in order to judge what will work.|
It's nice to learn from <johnlspouge> that Spielmann also agrees with me. It would be nicer still to hear that this is the consensus of present-day super-GMs (who are a cut above Spielmann in their ability).
|Dec-15-07|| ||whitebeach: <Jimfromprovidence: That won’t work because black’s bishop will intervene.|
If white plays 20 bxh6 then black will follow 20… gxh6. If white follows with 21 Qg4+ then 21…Bg5 blocks the attack.>
It's not quite that simple. In the first place, white doesn't play 21. Qg4+ but Rg3+. If then . . . Bg5 22. h4 will win the pinned B with a serious ongoing attack against the vulnerable black king (while also relieving white's own back rank vulnerability).
Only two other legal replies exist to 21. Rg3+: 21 . . . Kh8 and 21 . . . Kh7.
On 21 . . . Kh8 22. Qh5 Kh7 (if 22 . . . Bg5 23. Rxg5) 23. Rh3 and now 23 . . . Bg5 is forced, after which 24. Ne4 and black is in deep trouble. On 24 . . . Qd8, Rg8, or f6, 25. Nxg5+ does the trick (if in reply either 25 . . . Rg5 or fg5, Qxh6+, while if 25 . . . Qxg5, then 26. Qxg5 wins the queen). On 24 . . . Nf6 25. Nxg5+ again wins. Even a try such as 24 . . . Bf4 meets with 25. Ng5+ Bxg5 26. Qxg5, when black is finished.
So the critical line is 21. Rg3+ Kh7, and only now 22. Qg4. Only two moves avert immediate checkmate: 22 . . . Bg5 leads, after 23. Ne4, to lines similar to those already discussed. Probably the better move is 22 . . . Bf6. But now 23. Ne4, and it's hard to see what black can answer. If his N moves, then 24. Nxf6+. His B can't retreat or 24. Qg7# (or if 23 . . . Bh8 24. Qf5#). Meanwhile, if 23 . . . Rg8, 24. Qxd7+! when if 24 . . . Qxd7 25. Nxf6+ followed by 27. Nxd7 and white is a piece and a pawn up. 23 . . . Qd8 can lead to similar play but with white only retaining a pawn lead, or to a continuing attack aimed at the black king, which is too complicated to go into further here but looks promising for white.
In fact all of this touches only on the main themes; there are just too many side possibilities to detail in this space--but so far, all of them that I've looked at point to a win for white. Of course I'm sure there's plenty I haven't seen in this tricky position, and very possibly there's a clear refutation of white's sac. But the simple bishop interposition you suggest isn't it.
|Dec-15-07|| ||Jimfromprovidence: <whitebeach> <So the critical line is 21. Rg3+ Kh7, and only now 22. Qg4. Only two moves avert immediate checkmate: 22 . . . Bg5 leads, after 23. Ne4, to lines similar to those already discussed. Probably the better move is 22 . . . Bf6. But now 23. Ne4, and it's hard to see what black can answer.>|
Black can play 23… f6. If 24 h4 then 24…Nc5. Then 25 Nxc5 Qxg4 26 Rxg4 dxc5 27 hxg5 hxg5.
Now it’s an even rook and pawn endgame.
|Dec-16-07|| ||whitebeach: <Jimfromprovidence: [After 21. Rg3+ Kh7 22. Qg4 Bg5 23. Ne4]
Black can play 23… f6. If 24 h4 then 24…Nc5. Then 25 Nxc5 Qxg4 26 Rxg4 dxc5 27 hxg5 hxg5.|
Now it’s an even rook and pawn endgame.>
After 23 . . . f6 there is no need for white to play h4, allowing black (as you point out) to force an exchange of queens and a drawn ending. He has two other obvious possibilities. One is an immediate 24. Nxd6, gaining a pawn and trying to drive the black Q off the exchanging diagonal. Now if it were only a question of whether the black Q goes to c7 or d8 (else 25. Qxd7+), then white would achieve a powerful attacking bind with Nf5 or perhaps Qf5+. But after 24. Nxd6, instead of moving his Q, black can also try 24 . . . f5?! This leads to wild complications in which, as best I can determine, white comes out with four pawns for a piece (with queens off the board).
So if white doesn’t want to go in for this rodeo, he plays 24. Qf5+, pretty much forcing 24 . . . Kh8 (and preventing . . . f5). And now 25. Nxd6 Qc7 (what else?) 26. Ne4. or perhaps instead even 25. Rc3 Nc5 etc. It’s of course impossible to envision all the possible lines (for example, after 26. Ne4 Qc2 is interesting), but as far as I can tell, in all of them it’s white who’s forcing the initiative, often either regaining his piece with pawns besides or at the very least getting a couple of dangerous advanced pawns for it, and never in any real danger of losing while having all the winning chances.
So again, since white certainly doesn’t have to, and in fact shouldn’t, play your suggested 24. h4 but has much stronger options, 23 . . . f6 isn’t by any means a clear refutation of white’s bishop sac on h6 a move earlier than in the actual game.
Fascinating stuff, isn't it?
|Dec-16-07|| ||Jimfromprovidence: <whitebeach> <So again, since white certainly doesn’t have to, and in fact shouldn’t, play your suggested 24. h4 but has much stronger options, 23 . . . f6 isn’t by any means a clear refutation of white’s bishop sac on h6 a move earlier than in the actual game>.|
Your contention is that the same sacrifice, one move earlier, is just as strong or stronger than the game continuation. This means that you have to show conclusively that white wins at least an equivalent amount of material as the game continuation, which the earlier posts showed is roughly a piece.
Even with all of the options you've come up with, that proof is not yet established.
|Dec-16-07|| ||whitebeach: <Jimfromprovidence: Your contention is that the same sacrifice, one move earlier, is just as strong or stronger than the game continuation. This means that you have to show conclusively that white wins at least an equivalent amount of material as the game continuation, which the earlier posts showed is roughly a piece. |
Even with all of the options you've come up with, that proof is not yet established.>
Actually, I believe it was you who pointed out that black had a better 20th that would have made the game sacrifice ineffectual. Thanks. That’s what got me looking into whether the sac could be played a move earlier. I think I’ve showed pretty conclusively that it can, with a strong initiative for white, who at the very worst will have two pawns for a piece for his attack. Is that worth “an equivalent amount of material as the game continuation”? Maybe not, if you want to lawyer about it. But it seems to me that, especially in a sacrificial line, material is less the point than winning is. And let’s face it, none of your suggested replies so far has actually refuted the early sac.
BTW, looking over your line with 23 . . . f6 (which I had not considered before you came up with the idea), I saw a still stronger continuation for white, 24. Rh3. Now, for example, 24 . . . Nc4 fails immediately after 25. Nxg5+ fxg5 26. Qxg5. And black no longer has 24 . . . f5 because of 25. Qxg5. Another try is 24 . . . Qd8, but after 25. Qh5 it’s curtains. Somewhat better is 24 . . . Qe8 but 25. Nxd6, while not yet winning “an equivalent amount of material,” is going to make life very difficult for black. It seems that black’s best hope is 24 . . . Rg8, when 25. Rc3 Qd8 26. Qf5+. Again, no “equivalent amount of material” quite yet, but after either 26 . . . Kh8 27. Nxd6 or 26 . . . Rg6 and now maybe 27. h4 Bxh4 27. Rh3 Bg5 28 R(a)a3, who would you say is more likely to win the game?
|Dec-16-07|| ||Jimfromprovidence: <whitebeach> <BTW, looking over your line with 23 . . . f6 (which I had not considered before you came up with the idea), I saw a still stronger continuation for white, 24. Rh3.>|
In summary, my original point was that if black had played 20… Nf6 instead of Bc7, he would have been in much better shape; that white would have had less than a pawn advantage instead of a three-point advantage. That’s what I said.
Making the sacrifice a move earlier could or could not be better than the continuation I favored, but it does not appear from your posts that it is better than the actual game continuation.
I’m done with this game.
|Dec-17-07|| ||whitebeach: <Jimfromprovidence: Making the sacrifice a move earlier could or could not be better than the continuation I favored, but it does not appear from your posts that it is better than the actual game continuation. |
I’m done with this game.>
Yeah, me too. You seem like an OK guy, Jim--maybe a little curmudgeonly, but then I'm that way myself. I'd bet if we sat down over a chessboard we'd have a good game and a good time, so don't take the following as unfriendly.
I didn't sign some contract to "prove" that my early sac gained some certain amount of material or was better than the "actual game continuation." Inspired in fact by your own observation that black had erred on move 20, I wondered if white couldn't make his sac a move earlier. I found some very interesting (to me at least) lines that suggest he certainly could, and I posted them. (Maybe in the first rush of discovery I overstated a little. Sue me.)
This kind of analysis appears to be one of the main things this forum is about. So don't get all huffy. I enjoyed it, and I suspect you did too.
But I'll still take white's position after my sac and let you play black. Say a hundred bucks? (No computers allowed.)
|Dec-17-07|| ||Jimfromprovidence: <whitebeach> <This kind of analysis appears to be one of the main things this forum is about. So don't get all huffy. I enjoyed it, and I suspect you did too.|
But I'll still take white's position after my sac and let you play black. Say a hundred bucks? (No computers allowed.)>
I like the site because with my analytical background I think I can hold my own with the other kibitzers.
I enjoy exploring alternative positions, playing devil's advocate and engaging with the other kibitzers.
But once it's a new day I simply want to move on to the most current puzzle.
|Dec-17-07|| ||whitebeach: <Jimfromprovidence: But once it's a new day I simply want to move on to the most current puzzle.|
Great. See ya later somewhere else.
|Dec-17-07|| ||MostlyAverageJoe: <whitebeach> & <Jimfromprovidence>|
I think you guys set a record for the longest lasting discussion about a daily puzzle :-)
< Earlier Kibitzing · PAGE 4 OF 4 ·