< Earlier Kibitzing · PAGE 2 OF 2 ·
|Oct-16-08|| ||AhmetMTF: I found the move easily, however instead of 35.Bg6 (which eventually leads to a great pin on the Black's queen to his King) I thought to play Bxb7. (which misses a great opportunity) Nonetheless with Bg6, though white would be both positionally and materially in advantage, the game is far from over. (Or do i miss something fellows?) I think the continuation would be: 35.Bg6-Nxg6 36.Rxe8-Rxc4 37.Qd2-Rf7 38.Rxf8 Rxf8 39.Qd5 Kh7 40.h5-Rc1+ 41.Kg2-Rxa8 42.hxg6 Kxg6 43.Qxa8.|
|Oct-16-08|| ||gtgloner: Got it. The knight sac sets up a winning pin on the 8th rank.|
|Oct-16-08|| ||Woody Wood Pusher: 32.Nxe4,fxe4 33.Bxe4, Rcc7 34.Bxg6,Nf6
was the defense I saw.
33...Ne7 ties black up even more IMO
34.Ra8,Rcc7 35.Bg6 + -
anybody else think 33..Rcc7 and 34..Nf6 is a tougher defense for black?
|Oct-16-08|| ||chrisowen: Lev Polugaevsky plays 30..Bxc6 thinking he can win a pawn, 27..Bxb5 would have been better. Nxe4 fxe4 Bxe4 Ne7 then Ra8! Shuffling the rooks couldn't differ things, Rcc7 Bg6 and that's it.|
|Oct-16-08|| ||zb2cr: I saw 32. Nxe4, fxe4; 33. Bxe4, Ne7; 34. Ra8, but was unable to find the final follow=up move, 35. Bg6. Instead I settled for 35. Bxb7, Rxb7, leaving material even but with Black severely restricted in mobility. Oh well.|
|Oct-16-08|| ||5hrsolver: I totally missed the 33.. Ne7 defense. And I totally missed 35.Bg6. I was so focused on capturing one of the rooks. If I was paying attention I would have noticed black's weak back rank and the opening of the e file. This was supposed to be a 'medium'.|
|Oct-16-08|| ||JG27Pyth: Ugh. Spent too much time calculating the lines if black declines and I missed the text defense. |
Anyone else think, as I do, Polugaevsky resigned a bit early? He's losing certainly...but after Bg6 black has several ways of going to Q+R vs R+R+N, which IMO is like being down the exchange -- your winning chances are gone, but you've got enough to justify playing on trying to swindle the draw.
|Oct-16-08|| ||Patriot: This was tough. I wanted to play 32.Nxe4 instantly but the hard part is working out the details to make sure it works or at least see deeply enough to know that it doesn't lose. With that in mind, I probably would've played 32.Nxe4 against anyone in a 30 minute game without being able to work out all the details. Materially, black is up a pawn so if white can at least equalize then 32.Nxe4 is worth a try.|
So if simply 32.Nxe4 fxe4 33.Bxe4 Rcc7 34.Bxb7 Rxb7, white gets 2 pawns and a rook (worth about 7 pawns) for two pieces (worth about 6.5 pawns). And since white was a pawn down to begin with, this leaves black with about half a pawn advantage. I would play it based on this fact alone without doing a thorough analysis which isn't always possible in a fast game (like 30 minutes). It takes about 1 pawn advantage to be "winning" and if you can reduce your opponents pawn advantage to half a pawn, it's closer to a draw.
After analyzing, I saw that I made a key mistake early on. I figured after 32.Nxe4 what if black tries to hold the pawn with 32...Rxc4? Things then got more complicated when trying to play Qb3 or Qa2 and win the exchange. But white can simply play 33.Nf6+ Nxf6 34.Bxb7. Materially, the exchange is worth about 1.75 pawns and this would leave white with a 3/4 pawn advantage.
So from an OTB point of view, I don't think much analysis is required. From a "solve the puzzle" point of view, early analysis would suggest 32.Nxe4 fxe4 33.Bxe4 as the principal variation to start with.
|Oct-16-08|| ||ChessApplet: User: Woody Wood Pusher
But white could just take the rook instead of knight in the 34th move which is an advantage for white if I am not missing something. Time to check.|
|Oct-16-08|| ||kevin86: What started as a fork-skewer turns into a boa-type mating net.|
|Oct-16-08|| ||Marco77: <Puffen: What about 32.Ra8? Can't see how it's not as good as nxe4>
|Oct-16-08|| ||Patriot: ChessApplet: Woody Wood Pusher's line is better. After 32.Nxe4 fxe4 33.Bxe4 Rcc7 34.Bxg6, white wins a whole piece. 34.Bxb7 Rxb7 only wins the exchange. It's better to win a whole piece than the exchange.|
In my previous analysis, I have to point out that I looked at Bxb7 which is inferior to Bxg6, but was mainly trying to demonstrate an OTB thought process to see if 32.Nxe4 should be considered at all. Because OTB all you need to do is find the best move, and if simple analysis can show that it leaves you with at least a better evaluation then the move can usually be played. You have to be careful though when using this approach and not miss a candidate move by your opponent that refutes your move in some way (e.g. a mating attack or simple refutation that wins material).
|Oct-16-08|| ||YouRang: Our bishop being in-line with the two black rooks was certainly an eye-grabber. We just have to sac our knight for the 2 black pawns, leaving our bishop on e4 spearing the rooks and forking the knight.|
The natural move for black (i.e. the only move I considered) was 33...Ne7, protecting the knight and guarding the c6 rook. However, this leaves white with the pleasant situation of having a free move (the rooks are still speared, so our threat of winning the exchange isn't going away).
It took me a moment to find the best move to exploit this situation, but I finally noticed that after our bishop and black's knight clear the e-file, our rook will be attacking the Ne8, and so 34.Ra8! setting up the double attack on that knight came into view.
I didn't look any further that this, but I felt satisfied that black was in hot water.
|Oct-16-08|| ||soberknight: Bah, didn't see anything past winning a rook and two pawns for two minor pieces.|
|Oct-16-08|| ||benveniste: I also spent a lot of time looking at what happens if black declines with 32. ... c8. I could find nothing better for white than 33. c3. White has a pawn and the superior position, but with all the major pieces still on the board it's going to be a struggle.|
|Oct-16-08|| ||slapwa: benveniste: No - if 32 ..., Rc8; 33 Nf6+ and the b7 rook goes.|
|Oct-16-08|| ||DarthStapler: I just saw that I could win a rook and two pawns for a bishop and a knight and thought that was good enough since some of these puzzles were just the win of one pawn or something|
|Oct-16-08|| ||beenthere240: So, for the people who think declining the sac negates this puzzle, what's move 32...? As slapwa points out 32....Rc8 is a bust.|
|Oct-16-08|| ||johnlspouge: Thursday (Medium):
Lombardy vs Polugaevsky, 1978 (32.?)
White to play and win.
Material: B for N+P. The Black Kg8 has 3 legal moves and is open to check on the a2-g8 diagonal. Both Black Rb7 and Rc6 are loose, as is Ng6. The White Ra1 has the open a-file; and Qb2 has the semi-open long diagonal a1-h8 terminating at Pg7. The White Kg8 is secure. The White Nd2 and Bg2 have limited scope and require activation, but they both focus on Pe4. Given the conjunction of Bg2, Pe4, Rc6, and Rb7 on the long diagonal a8-h1, the action is likely to be on the Q-side. Capture at e4 is interesting, and the piece remaining there should be Bg2, to skewer Rc6 and Rb7 while forking Ng6. The capture might also open the e-file, activating Re1 with the threat Rxe8.
Candidates (32.): Nxe4
32.Nxe4 (threatening 33.Nf6+ or 33.Nd2 then 34.Bxc6 or 34.Bxb7)
Black can accept the sacrifice:
Candidates (33.): Bxe4, Rxe4
33.Bxe4 (threatening 34.Bxc6 or 34.Bxg6)
Black has only 2 responses to avoid being immediately at least a P down:
(1.1) 33…Ne5 34.Bd5+ (threatening 35.Rxe5)
White recovers at least the piece and remains a P up.
(1.2) 33…Ne7 34.Ra8 (threatening 35.Bxc6 36.Rexe8)
34...Rcc7 35.Bg6 (threatening 36.Rxe8)
White remains up Q for R+N.
Black can decline the sacrifice:
White has regained material balance and can withdraw with 33.Nd2 with a superior game.
|Oct-16-08|| ||johnlspouge: <dzechiel> let me know that he is on vacation until Monday's puzzle.|
|Oct-16-08|| ||johnlspouge: Toga II 1.3.1 indicates that refusal is best but still losing. (Humans can improve near the end of the full computer variation.) I give the 12-ply analysis, because it includes the "human" response 34...Rxa1.|
[ply 12/34 time 00:02 value +2.85]
32…Rcc7 33.Nc3 Ra7 [else, Bxb7] 34.<Nd5> Rxa1 35.Qxa1 Rxc4 36.Qa8 Nc7 37.Qa2 Ne5 38.f4 Nxd5 39.fxe5 Rd4 40.Bxd5+ Kh7 41.e6 Rxb4 42.e7 Qe8 43.Qd2
[ply 15/49 time 01:04 value +2.98]
32…Rcc7 33.Nc3 Ra7 [else, Bxb7] 34.<Nd5> Rcb7 35.Rxa7 Rxa7 36.c5 Rf7 37.Qe2 bxc5 38.Qxe8 cxb4 39.Qxf8+ Kxf8 40.Re6 Ne7 41.Nxb4 Nc8 42.Bd5 Re7 43.Nc6 Rxe6 44.Bxe6 Ne7 45.Nxe7 Kxe7 46.Bxf5 d5 47.Kg2
|Oct-16-08|| ||johnlspouge: < <JG27Pyth> wrote: Ugh. Spent too much time calculating the lines if black declines and I missed the text defense.>|
Hi, <JG27Pyth>. I was not very happy with my analysis of what happens if Black declines, but my general rule of thumb is if acceptance is off-limits, the sacrifice is probably the best move.
Today, the attitude paid dividends, because the analysis of Black declining felt about at a Saturday level, more time than a working stiff like me can spend on a Thursday. I saved myself a lot of time.
|Oct-16-08|| ||al wazir: <kirchhoff: If black turns down the sac with 32...Rc8 then white can play 33. Nf6+ and wins a R and P for the knight with a nice position.>|
After 32...Rc8 33. Nf6+ Qxf6 34. Qxf6 (what else?) Nxf6 35. Bxb7 Rxc4, black has ++ vs. +. That's nothing to write home about, but it's better than the game line
|Oct-16-08|| ||yoozum: I didn't get the exact sequence of moves here, but I realized that the initial knight sac was the way to go and how the knight on e8 had to be eliminated and the seventh file had to be closed off for the black rooks.|
|Oct-17-08|| ||whitebeach: <al wazir: But if I had been black I would have played 32. Rc8 instead of accepting the sac. (Now material is even).
After that I think white has the advantage, but no easy win. If 33. Nxd6, then 33...Nxd6 34. Bxb7 Nxb7.>|
Your line is for sure better than the game continuation, but after 35. Ra7 black is in serious trouble. Black needs to defend the knight or move it. There are very few possibilities. Certainly not 35 . . . Nd8 when 36. Re8! wins outright. 35 . . . Qf7 just pins the knight to the queen. On 35 . . . Nd6 36. c5 is strong. Best may be 35 . . . Rb8, but again 36. c5, and if, say, 36 . . . Ne7 (to prevent c6), then 37. Qe5 with powerful threats.
All in all, I don't see a defense for black after the offered knight sac in the game.
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