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|Sep-19-09|| ||parmandil: It is not so hard to see that 19.Rxd6 will give two minor pieces for the rook, but when did Dreev first see this? Playing through the game, I felt he must have seen it when he played 14.c5. But after checking a database, I rather guess it was part of his opening preparation!|
14.c5 was played the first time a year previously to this game, between Zvjaginsev and Kramnik in the Moscow olympics. Kramnik declined the pawn with 15...Bf8 and the result was a quick draw. Surely many would have been curious to why Kramnik didn't take the pawn, and it wouldn't take Dreev long time to find this almost forced variation in his study.
|Sep-19-09|| ||whiteshark: 20.Ne4 is really a strong move. It creates a few strong threats (Nf6+/Bc5).|
|Sep-19-09|| ||johnlspouge: Saturday (Very Difficult)
Dreev vs R Cifuentes-Parada, 1995 (19?)
White to play and win.
Material: Down a P. The Black Kg8 has 3 legal moves, all dark squares. The White Ng5 attacks light squares in the unguarded Black K-position, but with a lack of local superiority (the White Q on a4, in particular), prospects for a K-side attack remain slim, unless coupled with other tactical opportunities. The White Qa4 attacks Nb4, so removal of the Black Bd6 guarding it makes 19.Rxd6 an attractive candidate. The White Kg1 is vulnerable to 19…Bxh2+, increasing the defensive value of 19.Rxd6.
Candidates (19.): Rxd6
19.Rxd6 Qxd6 [else, drop a B]
20.Ne4 (threatening 21.Bc5, forking Qd6 and winning Nb4)
Adequate counter-attack is not available, so Qd6 must retreat.
(1) Black can try counter-attack:
20…Qd5 21.Nf6+ (forking Kg8 and winning Qd5)
The resource 21.Nf6+ snuffs all hope. Without it, 21.Qxb4 c5 permits Black to recover the piece by pinning Ne4 to the mate threat 22…Qxg2#, an embarrassing end to White’s combination.
(2) Black can attempt to maintain contact with Nb4, but loses Nb4 anyway:
20…Qe7 [or Qf8] 21.Bc5 Q any [else, drop Qe7]
White captures Nb4, leaving him with B+N for R+P. With the Black dark-square Bd6 gone, the weak dark squares on the K-side make the Black K an easy target.
|Sep-19-09|| ||johnlspouge: < <parmandil> wrote: [snip] when did Dreev first see this? Playing through the game, I felt he must have seen it when he played 14.c5. [snip] >|
Hi, <parmandil>. Your detective work on 14.c5 Nxc5 (after which everything is forced) is a great example of why the CG daily puzzle is a unique resource for chess players. Thank you (and thanks to CG) for the interesting story.
|Sep-19-09|| ||lostgalaxy: Yes, the combo did start at move 14.c5 sac a pawn!|
|Sep-19-09|| ||monopole2313: Got the first couple of moves for White. I figured White needed a blockbuster to counter Nd5 for Black.
From the final position, White wins with Bf6+ and Rh1->h8.|
|Sep-19-09|| ||Marmot PFL: <Today's puzzle was relatively easy>|
I have to agree. Black has dark sq weaknesses on the kingside and a loose knight on b4. Taking out the Bd6 followed by Ne4 with threats of Nf6+ and Bc5 was not hard to see and white can play it without risk (unless I overlooked something).
|Sep-19-09|| ||Jimfromprovidence: Instead of 18... Nb4, 18...Bxh2+ 19 Kf1 Be5 20 Bxa6 Bxa6+ 21 Qxa6 Bxb2 seems like it leaves a lot of work to be done.|
click for larger view
|Sep-19-09|| ||Eduardo Leon: <MarmotPFL>, the only thing that was not too easy to see was that black couldn't control the open d file, because the white bishops protected the d1-d4 squares. Besides that, everything was self-suggested.|
|Sep-19-09|| ||chrisowen: Rxd6 is the obvious first choice as for white's dsb it dominates the board. The dfile is effectively closed so there's no chance black's rook can come into it.|
|Sep-19-09|| ||fm avari viraf: I think, the most logical move would be 19.Rxd6 Qxd6 20.Ne4 and Black can't defend his N. Therefore, White wins two pieces for the Rook with a dominant position. Of course, I don't see an immediate win for White but he has to fight a few tactical battles before cashing in his advantage.|
|Sep-19-09|| ||wals: Black played
15....Nxc5 lost equiv. of a pawn.
Should have played 15...Bf8 and not lose ground.
18....Nb4 lost equiv. of a pawn.
Should have played 18....Bxh2 and not lose ground.
32....hxg6 and lost a whopping equiv. of 6 pawns.
Should have played 32....Kxg6 and prayed brandy fumes would get to Dreev.
Rybka 3 1cpu time 3min 37 ply 16.
|Sep-19-09|| ||Alexwlh: awesome, black cannot do anything in the middle game, every important square was nicely controlled by white|
|Sep-19-09|| ||gofer: 19 Rxd6
19 ... Qxd6
20 Ne4 winning
20 ... Qe7 21 Bc5
20 ... Qf8 21 Bc5
20 ... Qd5 21 Nf6+
20 ... Qe5 21 Qxb4
19 ... c5 29 Rd7 winning
So what have I missed??? Time to check...
|Sep-19-09|| ||WhiteRook48: I actually got it...|
|Sep-19-09|| ||LIFE Master AJ: When I first looked at the position, a few things flashed through my mind. |
However after less than 1 minute, (it takes about that long to work through my checklist); I instantly settled on 19.Rxd6.
It took another 7-10 minutes to work things out to the 23rd move.
Quite a few people have already gone through this problem, yet I have not seen anyone point out what I saw, so ...
19.RxB/d6!, QxR/d6; 20.Ne4, Qe5.
...Qe5 is completely forced, otherwise Black gets into trouble. For example, 19...Qe7?; 21.Bc5 Qd8; 22.Qxb4 Bc8; (22...Rb8?; 23.BxP/a7, etc.) 23.Rd1 Qh4; 24.g3 a5; 25.gxh4 axb4; 26.Nf6+ Kh8; 27.Nxe8, " " (I want to stress that this is NOT a Fritz line, just one of the lines I looked at in my analysis!)
21.QxN/b4, Red8; (This is forced to prevent a winning -fork on d6, Black also gets out of a possible fork on the f6-square as well. Black is not worried about 22.QxB/b7, as he has 22...QxN/e4.)
Here, I was not as sure of what to do, however 22.f4!? was a candidate simply because it kicked the BQ out of the center. Black has many moves, but I finally settled on 22...a5!?
I did NOT see the way the game ended ... that may have been part of what Dreev saw. (Black's lack of a dark-squared Bishop turned out to be HUGE, Black's inability to protect the dark-colored squares near his King is really what did him in.)
The only question is: "Do I get credit for solving the puzzle?"
ChessGames, your input is required here. How much did you need to see in order to receive credit for solving this one? (Usually Saturday puzzles require a minimum of 5-7 moves of looking ahead.)
|Sep-19-09|| ||LIFE Master AJ: Please note that I WANT you to read the other kibitzes! Usually <dzechiel>, <Once>, <TheBish> (and many others!); have already given detailed estimates of the beginning position. (I consider it a waste of my time to continuously repeat what has already been pointed out by others.)|
|Sep-19-09|| ||LIFE Master AJ: As <Parmandil> first pointed out, this combination actually begins with 14.c5!! At this point, Dreev must have already worked things out close to ten moves ahead. He certainly already saw that he would win two minor pieces for a R+P, and also have a dominating position.|
|Sep-19-09|| ||CHESSTTCAMPS: Black is up a shaky pawn with a kingside majority, but the black position has significant weaknesses: The Nb4 is only defended once, the queenside pawns are split, the c-pawn blocks the Bb7, and the kingside pawn structure invites an attack on the dark squares. All of these factors point to one move for white:|
This is easy to understand both on technical and tactical grounds. Removing the bishop stops the superficial attack on h2, but more importantly, it enhances white's chances to attack the kingside dark squares and destabilizes the Nb4.
The only plausible continuation; h6 or f6 is met by 20.Qxb4 and 19... Nd5 is met by 20.Bc5, remaining a comfortable piece ahead. But now
20.Ne4 leaves black no good way to defend both the Q and the Nb4:
A) 20... Qe7 21.Bc5 (Bg5 Qf8 22.Nf6+ looks good, but I can't find a clear win) Qh4 22.Qxb4 f5 23.f4! (to seal off the black queen and ruin black's pawn structure) fxe4 24.Qxb7 with a material advantage (2Bs for a R), lots of weak black pawns to pick off, and a vulnerable black kingside, this is easily won.
A.1) 23... Rab8 24.Nd6 Red8 25.Bxa7 is winning for white.
B) 20... Qxe5 21.Qxb4 f5 22.Nd6 c5 23.Qf4 Qxf4 24.Bxf4 Re7 (e5 25.Nxe8 exf4 26.Nd6 is no better) 25.Nxb7 Rxb7 26.Bf3 cleans up quickly for white.
C) 20... Qf8 21.Bc5 wins the Nb4 without any counterplay chances for black.
Time to check.
|Sep-19-09|| ||benjinathan: I am a bit late withthis question, but here goes: Is 19.Rxd6 justified on its own (positional merits) or is it only the fact that white picks up the knight too, that makes Rxd6 appropriate?|
|Sep-19-09|| ||MaxxLange: <benjinathan> do you mean, in this position, would an exchange sac for the bishop been good, even if White somehow couldn't get a second piece for his Rook? Or, in general, are you asking, is that kind of sacrifice positionally justified?|
In the second case, of course "it depends" on the exact position, but the exchange sac is very often used as a middlegame method to try to make one's minor pieces better.
|Sep-20-09|| ||benjinathan: <do you mean, in this position, would an exchange sac for the bishop been good, even if White somehow couldn't get a second piece for his Rook?>|
Right-it is this. Sorry I was not clear.
To be more clear-do the positional qualities which have been discussed in the interesting posts above (esp. the dark squared weakness) justify the exchange sac where the piece being exchanged is the dsb...in this position?
|Sep-20-09|| ||benjinathan: I am thinking not. I think the positional advantages lose out to tactics, piece exchanges and, if not lost, that knight will be strong on d5.|
Maybe, this is simply the full answer:<In the second case, of course "it depends" on the exact position,>
|Sep-20-09|| ||MaxxLange: it's kind of attractive to just kill that dark squared bishop where it stands. The DSB looks pretty strong. I'm sure it would at least feel good to chop it off with the White Rook! But that kind of general principle based analysis will keep you down at my rating :)|
To make up a position close to this puzzle, but where White doesn't get the b4 Knight after Rxd6, you would have to change something: either the Knight would need to be on a different square, or something else would have to be on a different square, defending the Knight, or White would have to have some vulnerability that made it tactically impossible to take the second piece.
Analyzing such positions would be a really interesting and difficult training project
|Sep-20-09|| ||johnlspouge: < <benjinathan> wrote: [snip] Is 19.Rxd6 justified on its own (positional merits) or is it only the fact that white picks up the knight too, that makes Rxd6 appropriate? >|
Hi, <benjinathan>. Computer evaluation is useful as an approximate but reproducible measure of a position. <patzer2> initiates a thread concluding that the B+N for R+P advantage resulting from the combination is worth +2 P but not +3 P. The answer to your question is therefore: yes, White requires the win of Nb4 (or its equivalent) to justify the combination.
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