|Feb-05-15|| ||ketchuplover: Kudos to Hikaru on his tourney victory|
|Feb-05-15|| ||Eduardo Bermudez: Already bought the book: "How to get only half point from the rook endgame with decisive advantage"? written by Nakamura?|
|Feb-05-15|| ||JointheArmy: <Eduardo Bermudez> Can you show us the winning line, please?|
|Feb-05-15|| ||SirRuthless: Yes <Eduardo> Do pray tell...|
|Feb-05-15|| ||patzer2: Fritz 12 indicates Black might have won with 51. Ke2! when play might go 51. Ke2! Ra4 52. Ke3 Ke7 53. g5 Ra1 54. Kd4 Ra3 55. f4 Ra4+ 56. Kc3 Ra3+ 57. Kc4 Ra4+ 58. Kc5 Ra3 59. f5 gxf5 60. g6 fxg6 61. Rh8 Rxa7 62. Rh7+ .|
The idea is to infiltrate the Queenside with the White King and to sacrifice pawns on the King side to clear the way for a skewer attack.
White missed the same winning idea earlier by not playing 48. a7! when play might go 48. a7! f6 49. Kd2 Ra2+ 50. Kc3 Ra3+ 51. Kc4 Ra5 52. Kb4 Ra6 53. Kc5 Ra2 54. Kd6 Ra6+ 55. Kd7 Ra4 56. Ke8 Ra3 57. Kf7 Ra5 58. Kf8 Ra6 59. Kg8 Ra2 60. Kh7 Ra3 61. Kh6 Ra2 62. g4+ hxg4 63. fxg4+ Kxg4 64. h5 gxh5 65. Rg8+ Kf3 66. a8=Q+ .
The idea here is to also move the White King to the Queenside and to sacrifice pawns for a safe Rook check followed by the pawn promotion.
|Feb-05-15|| ||patzer2: With a hefty first place cash prize awaiting for a safe draw, I can see Naka's point of not trying to force the issue and risking losing here.|
|Feb-05-15|| ||SirRuthless: I think any lines showing a white kill are simply engine noise. Why should black ever play f6? The idea for black, once a7 is pushed is just shuffle the king between f5 and f6, shielding from any rook checks along the 8th rank as the white king approaches the queen side, then when the white king reaches a square touching the black rook just move the rook between a1 and a6 out of range of the king, any time the king tries to approach a7 and release the white rook from guard duty or escort the pawn , just check the king from behind and the white king has no shelter. Essentially the white king can never avoid all the checks and the R on a8 can never leave post or the a7 pawn drops. This is a theoretical draw. If there is some strange chance to create a kill for white it probably involves pushing kingside pawns and hoping black makes some silly capture but that pawn on a7 is never going to queen because there is no way to release the rook from a8, escort the pawn and avoid checks on the white king all at the same time.|
|Feb-05-15|| ||Eduardo Bermudez: Stockfish 5
1: (2.50)  47. Ra8 Ke5 48. a7 Kf5 49. Kd2 Kf6 50. Kc2 Ke7 51. Kb2 Ra4 52. Kc3 Ra3+ 53. Kb4 Ra1 54. Kb5 Ra3 55. Kc5 Ra1 56. Kc6 Ra3 57. Kb5 Ra2 58. g4 Ra1 59. Kb4 Ra2 60. Kc5
|Feb-05-15|| ||devere: <patzer2: Eduardo Bermudez:>|
It is basic that to avoid the skewer attack Black must keep his king on g7, h7, or another sheltered position (such as f6 sheltered by a pawn on f7). It seems to me that your engines, suffering from a horizon effect, did not defend properly for Black. I'd be quite surprised if you can demonstrate a win with proper defense for Black.
|Feb-05-15|| ||patzer2: <Devere> Maybe it's as <SirRuthless> says "engine noise" showing winning advantages in these lines. |
Moreover, Nakamura had everything to lose and little or nothing to gain in risking his first prize money by going for a win in a difficult and risky endgame.
|Feb-05-15|| ||keypusher: The 4 v 3 R&P ending with an a-pawn is a staple of the endgame manuals and they all say it is a draw with proper play if the rook is in front of the pawn. Has that changed?|
|Feb-05-15|| ||greed and death: GM draws these days have zero effort put into them...|
In this game, for example, Black is clearly winning in the final position because of his more centralized king, yet both players agreed to a draw.
Shameful, I say!
|Feb-06-15|| ||keypusher: <patzer2> <White missed the same winning idea earlier by not playing 48. a7! when play might go 48. a7! f6 49. Kd2 Ra2+ 50. Kc3 Ra3+ 51. Kc4 Ra5 52. Kb4 Ra6 53. Kc5 Ra2 54. Kd6 Ra6+ 55. Kd7 Ra4 56. Ke8 Ra3 57. Kf7 Ra5 58. Kf8 Ra6 59. Kg8 Ra2 60. Kh7 Ra3 61. Kh6 Ra2 62. g4+ hxg4 63. fxg4+ Kxg4 64. h5 gxh5 65. Rg8+ Kf3 66. a8=Q+ .>|
In his <Endgame Manual> Dvoretsky discusses Unzicker vs E R Lundin, 1954, in which Unzicker carries out pretty much this exact plan (missing a mating combo on the way -- see the game page), except that when the king got to h6, instead of playing 1.g4+ and opening up the black king, he played 1.Rb8 Rxb7 2.Rb5+ and the white king devoured the black kingside.
But as Dvoretsky pointed out, the only reason the plan worked was that the black pawn was on f6 instead of f7. <When Black's pawn stands on f7, his king can return to f6 and g7 with an absolutely drawn position.>
Engines are great, but sometimes you're still better off reading a book.
|Feb-06-15|| ||SirRuthless: <devere> and <keypusher> have it right. Your engines are not understanding the fortress. Nakamura explained the idea in the post mortem pretty clearly that due to the position of black's pawns and the black king that it was nothing more than a draw.|