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|Aug-06-19|| ||whiteshark: <RainPiper: So, at least, it seems that keeping the rook on the second rank is much better than 93.♖xg3, and there is no straightforward plan for a Black win after this continuation.> At least our now installed SF engine seems to confirm this:|
click for larger view
White to move
1) -1.26 (55 ply) 93.Re2 Qc3+ 94.Kf4 Qc4 95.Rg2 Qd4 96.Kf3 Kd1 97.Rxg3 Kd2 98.Rg2+ Kc3 99.Rc2+ Kb4 100.Kf4 Qa7 101.Kf3 Qd7 102.Ke3 Qg7 103.Kd3 Qg5 104.Kd4 Qf6+ 105.Kd3 Qh6 106.Bg2 Qg6+ 107.Be4 Qg7 108.Ke3 Qe5 109.Kd3 Qg3+ 110.Kd4 Qg1+ 111.Kd3 Kb5 112.Bg2 Qd1+ 113.Rd2 Qc1 114.Rc2 Qf4 115.Be4 Qf1+ 116.Kd4 Qa1+ 117.Ke3 Qg1+ 118.Kd3 Qe1 119.Kd4 Qg3 120.Bd3+ Ka4 121.Be4 Qf4 122.Kd3 Kb5 123.Kd4 Ka5 124.Kd3 Qf1+ 125.Kd4 Kb4 126.Ke3 Qd1 127.Kf2
2) -1.26 (54 ply) <93.Rc2+ Kd1 94.Rd2+ Ke1 95.Rc2 Qg5+ 96.Kf3 Kd1 97.Rg2> Qh6 98.Bc2+ Ke1 99.Be4 Qh4 100.Re2+ Kd1 101.Rg2 Kc1 102.Re2 Qg5 103.Rg2 Qg7 104.Kf4 Qd4 105.Kf3 Kd1 106.Rxg3 Kd2 107.Rg2+ Kc3 108.Rc2+ Kb4 109.Kf4 Qa7 110.Kf3 Qd7 111.Ke3 Qg7 112.Kd3 Qg5 113.Kd4 Qf6+ 114.Kd3 Qh6 115.Bg2 Qg6+ 116.Be4 Qg7 117.Ke3 Qe5 118.Kd3 Qg3+ 119.Kd4 Qg1+ 120.Kd3 Kb5 121.Bg2 Qd1+ 122.Rd2 Qc1 123.Rc2 Qf4 124.Be4 Qf1+ 125.Kd4 Qa1+ 126.Ke3 Qg1+ 127.Kd3 Qd1+ 128.Ke3 Qe1+ 129.Kd3 Qh4 130.Kd4 Qf6+ 131.Kd3 Kb4 132.Ke3
3) -2.46 (54 ply) 93.Kd3 Qg5 94.Rg1+ Kb2 95.Rg2+ Ka1 96.Rc2 Qf6 97.Rd2 Qf1+ 98.Kd4 Qg1+ 99.Kd3 Qb1+ 100.Kd4 Qb6+ 101.Kd3 Qa5 102.Rg2 Qa7 103.Rd2 Qa6+ 104.Kd4 Qc8 105.Kd3 Qc1 106.Rg2 Qf4 107.Kd4 Qg5 108.Kd3 Qg4 109.Rd2 Qh5 110.Rg2 Qd1+ 111.Kc4 Qa4+ 112.Kd3 Qb5+ 113.Kd4 Qb6+ 114.Kd3 Qa5 115.Rd2 Qc5 116.Rg2 Kb1 117.Rd2 Qc7 118.Ke3+ Ka1 119.Kd3 Qg7 120.Rc2 Qe5 121.Rd2 Qf6 122.Ke3 Qc3+ 123.Ke2 Qc4+ 124.Ke3 Qc5+ 125.Kd3 Kb1 126.Rg2 Kc1
6.0 minute analysis by Stockfish 9 v010218
|Oct-09-19|| ||Cheapo by the Dozen: What calamaity did White avert by pitching the g-pawn on Move 64?|
|Oct-09-19|| ||Cheapo by the Dozen: A little different, and remarkably easy for a Wednesday for me.|
White doesn't seem to have any weaknesses. The king isn't subject to attack, the queen has a path of retreat, and the other pieces aren't hanging.
Oh, wait. the queen only has one major path of retreat. And the obvious move to cut it off, 22 ... Nd4, has to be played immediately or not at all. And it happens to have the virtue of closing down a lesser escape route, namely the one to b5.
|Oct-09-19|| ||Cheapo by the Dozen: Same question for the d-pawn in the 90s.|
|Oct-09-19|| ||agb2002: Black has a bishop and a knight for the bishop pair.|
White threatens Qxb5.
The white queen can move along the D-file and to 5 only. Therefore, 22... Nd4, with the double threat e6 and Ne2+:
A) 23.cxd4 e6 traps the queen.
B) 23.Bxd4 e6 24.Bxg7 exd5 25.Bxf8 dxe4 26.Bxh6 (26.Bxd6 removes one of Black's weaknesses and activates the queen) 26... Kxh6 27.fxe4 Qa7+ 28.Kh2 Qe3 looks good for Black.
C) 23.e5 Ne2+ wins an exchange.
D) 23.b4 e6 wins (the knight controls b3).
E) 23.Qxd4 Bxd4 24.Bxd4 e5 and White probably won't be able to build a fortress (25.Bb6 Qb7 26.Bxa5? Qa7+).
|Oct-09-19|| ||Walter Glattke: 23.Bxd4 Change compelling queen against other material, better ending for black, Stockfish -1.26 from 93-127th move, must change after 22.Nd4, others worse.|
|Oct-09-19|| ||saturn2: I saw 22...Nd4
23. Qxd4 Bxd4 24. Bxd4
23. e5 Ne2+
23. Bxd4 e6 24. Bxg7 exd5 25. Bxf8 Rxf8 26. exd5-
All with more or less material advantage for black.
|Oct-09-19|| ||charlesdecharemboul: This time I give not a line to the mate!|
|Oct-09-19|| ||saturn2: I would have played 23 e5 to keep the queen. Furthermore 27 Re1 concedes the exchange of rooks. Why not 27 Rf2?|
|Oct-09-19|| ||mel gibson: I didn't see that.
Stockfish 10 agrees with same line:
(22. .. Nd4 (♘c6-d4 ♗e3xd4 e7-e6 ♗d4xg7
e6xd5 ♗g7xf8 d5xe4 ♗f8xh6 e4xf3 ♗h6-d2 f3xg2 ♔g1xg2 ♕d7-e6 ♖f1-f2 a5-a4
♖c1-e1 ♕e6-d5+ ♔g2-h2 a4xb3 a2xb3 ♕d5xb3 ♖e1-e7 ♖c8-f8 ♖e7-c7 ♕b3-d5 ♗d2-e3
♔h7-g8 ♗e3-b6 ♖f8-e8 ♗b6-d4 b5-b4 ♖c7xf7 ♕d5xf7 ♖f2xf7 ♔g8xf7 c3xb4 ♖e8-e2+
♔h2-g1 ♖e2-e4 ♗d4-h8 ♖e4xb4 ♔g1-f2 ♖b4-b3 ♗h8-d4 ♔f7-e6 ♗d4-e3 ♔e6-d5
♗e3-f4 ♔d5-c5 ♔f2-e2 d6-d5 h3-h4 ♔c5-c4) +3.03/41 267)
score for Black +3.03 depth 41
|Oct-09-19|| ||Whitehat1963: So, how far were we supposed to see to conclude we “solved the puzzle? I was able to see only the next 40 or 45 moves, not all the way to move 102!|
|Oct-09-19|| ||malt: Spied 22...Nd4 23.e5
(23.B:d4 e6 24.B:g7 ed5 25.B:f8 )
(23.cd4 e6 24.R:c8 R:c8 and 25...ed5 )
23...Ne2+ 24.Kh1 N:c1
|Oct-09-19|| ||Halldor: I went for 22... Bd4 winning the bishop on e3, but if White takes then 23...e5, trapping the queen.|
I only looked briefly at 22...Nd4 and thought it wouldn't work since White could then play 23 e5, making an escape for the queen to e4, although losing the exchange after Night fork on e2.
|Oct-09-19|| ||zb2cr: It looks like 22. ... Nd4. And then whichever way White captures, ... e6 will collect the Queen.|
|Oct-09-19|| ||beenthere240: I think you “solve” the puzzle if you realize that Nd4 gives black a significant material advantage|
|Oct-09-19|| ||TheaN: After 22....Nd4 Black has already effectively trapped White's queen, it's just up to White how she goes.|
The only practical way I can see White saving the queen is 23.e5, but this runs into 23....Ne2+ -+, the other threat of Nd4.
White has two ways to go. 23.cxd4 looks logical but is way worse: 23....e6 24.Rxc8 Rxc8! -+ and the queen's trapped just as much.
After 23.Bxd4 e6 24.Bxg7 exd5 25.Bxf8 dxe4 -+ and the bishop's still trapped. 25....Rxf8 ∓ might be playable but keeps another weakness on the board. It was what I originally wanted to play though: I guess if the situation arose I would have played dxe4: the key is that the queen is definitely won for R+N.
|Oct-09-19|| ||TheaN: <Halldor: I went for 22... Bd4 winning the bishop on e3, but if White takes then 23...e5, trapping the queen.>|
The problem's Pb5. Ie 22....Bd4? 23.Bxd4 e6 24.Qxb5 +-.
|Oct-09-19|| ||gawain: Is this the least conclusive "winning" combination ever? Black traps White's queen and gives up rook and knight for it. White resigns--after 78 further moves!|
I concede that the trap is clever and the puzzle is Wednesday-worthy.
|Oct-09-19|| ||landshark: Because this was a puzzle I saw the solution quite quickly - but OTB in G15 format which is what I usually play, this is the type of opportunity I often miss -|
|Oct-09-19|| ||patzer2: I missed the clever obstruction and Queen trap combination, beginning with 22...Nd4!, solving today's Wednesday puzzle, because I didn't consider it. |
However, even after I saw the game continuation and looked at it with the computer, I had difficulty understanding why Black's advantage after 22...Nd4! 23. Bxd4 e6 24. Bxg7 exd5 25. Bxf8 Rxf8 26. exd5 (diagram below)
click for larger view
is three Pawns plus after the computer best move reply 26...h5 -+ (-3.27 @ 42 ply, Stockfish 10).
After all, in the diagrammed position, the material count, provided you use the modern valuation of the Queen at 9 Pawns, is even (20 Pawns for each side).
Back when I began to study Chess, the Queen was valued at 10 Pawns, which today would have made the calculation of this combination easier (21 Pawns for Black to 20 Pawns for White).
In this position (diagram above), the computer indicates the Queen (9 Pawns) is worth three pawns more than the Rook (5 Pawns), Bishop (3 Pawns) and extra Pawn (1 Pawn) White has as compensation for the exchange.
Apparently the superior mobility of the Black Queen in this position increases her value far more than the standard 9 Pawn assessment of piece point values.
For example, one of the three best moves for Black in the above diagrammed position is 26...Qf5 -+ (-3.28 @ 34 ply, Stockfish 10). If White attempts to protect the threatend d-pawn after 26...f5 with 27. Rfd1 (diagram below),
click for larger view
Black maintains a decisive advantage by attacking White's weak pawn structure with 27...Qe5 28. Kf2 b4 29. Rc2 bxc3 -+ (-3.49 @ 35 ply, Stockfish 10).
P.S.: White's decisive mistake appears to be 22. Qxd5?, allowing today's Wednesday puzzle solution 22...Nd5! -+ (2.58 @ 31 ply, Stockfish 10).
Instead, 22. exd5 Nb8 23. f4 ⩲ (+0.68 @ 33 ply, Stockfish 10) leaves White with the advantage.
|Oct-09-19|| ||dhotts: <Patzer2> it took a GM to bring the win home 78 moves later...If a GM truly is a piece up (+3) then it should happen much sooner. I tend to agree with you, the silicon evaluation is heavy handed in assessing the Black Queen's mobility.|
|Oct-09-19|| ||Damenlaeuferbauer: After long pondering, my then 18 years old German compatriot Niclas finally trapped the white queen with 22.-,Nd4! 23.Bxd4,e6 (she has no square on the whole board) 24.Bxg7,exd5 25.Bxf8,Rxf8 ... and won the game 80 moves later.|
|Oct-09-19|| ||Check It Out: I saw the queen trap, but could easily have blown the complicated endgame against a GM opponent.|
|Oct-09-19|| ||patzer2: <dhotts> <I tend to agree with you, the silicon evaluation is heavy handed in assessing the Black Queen's mobility.> Thanks! My thought is a plus 3 advantage for a computer or a strong Master is much different than a plus 3 advantage for a club or weekend tournament player. |
Even so, the game and puzzle are instructive in highlighting the fact that the value of the Queen in exchange for pieces of "equal value" is more dependent on the assessment of the position than it is on a general assessment of piece point values (e.g. 9 Pawns = 1 Queen).
In this case, I suppose the Queen is worth three extra pawns to a computer or strong GM and quite a bit less for amateur players.
|Oct-09-19|| ||Breunor: <What calamaity did White avert by pitching the g-pawn on Move 64?>|
Move 4 was Rd2, the pawn is lost on move 66-67; at that point white has to save the bishop so must abandon the g pawn after white played 66 Be4 and then Qe5.
The calamity that is threatened is Qb2! This wins unless the white bishop can get into position to defend the white pawn on a2. So white has to play Be4 and then lose the g pawn after Qe5.
This indicates that the position was untenable for white.
The white rook needs to stay on the second rand and to the left of the king to stop the black ding from taking the pawn on a2. The white king needs effectively to defend the rook on d2. If the rook goes to c2, black can chase it with the king with Kb1. But only the white king can then defend the pawn on g3.
The pressure from QB2 is then decisive, something has to fall.
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