| Oct-15-06 |
| arctic tern: What's wrong with 77. Rxh2? |
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Oct-15-06
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| Sneaky: You must be looking at the board upside down or something, 77.Rxh2?? and Black wins after 77...Rxh2. |
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Oct-15-06
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| al wazir: <arctic tern>: 77. Rxh2 Rxh2 78. e8=Q Rd2+ (78...a1=Q? 79. Qe5+ draws) 79. Kc8/Kc7 Rc2+ 80. K moves a1=Q wins. |
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| Oct-15-06 |
| arctic tern: Ah yes, I was only seeing al wazir's drawing line. |
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| Oct-15-06 |
| MarioBalibrera: Wow, this came pretty close to a draw by the 50-move rule. Does anybody know any games where a theoretically won position is drawn by this rule? |
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| Oct-15-06 |
| syracrophy: Look at a charming fact of this game:
click for larger viewIt's move 104, and it's black's turn. If it would have been White's turn on this position, he would have been hopelessly lost, now, check this:
click for larger viewIt's move 119, and it's the same position as in move 104, but now it's White's turn, and he is in zugzwang! Check the variants: a)120.Rh8 Qe7 121.Kg8 Kg6 <zugzwang!> b)120.Rh6 Qe7+ wins the rook
c)120.Rh3 Qd7+
d)120.Rh2 Qd7+ 121.Kg8 Qc8+ 122.Kg7 Qc7+
e)120.Rh1 Qd7+ 121.Kg8 Qc8+ 122.Kg7 Qb7+
Another example of this kind of zugzwang is the following position from the game Carlos Torre vs Opocensky, 1925: 
click for larger viewIt's move 48, and it's White's turn. Check that if in the position it was Black turn, he would immediately be in zugzwang: if the black rook moves from the f-file, the move f5! would be too strong, and if the rook moves from the 3rd rank, White plays Kd3 and Be3, and if the bishop moves, Ra8 is crushing. Now check the next sequence that Torre played to return to same position, but with black's turn to play: 48.Rh8! Rg3 49.Rf8 Ke7 50.Rf6 Rf3 51.Rg6 Kd7 52.Rg8!
click for larger viewIt's just the same position as in move 48, but it's now Black's turn! See the game to see the continuation |
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| Oct-15-06 |
| patrikey: <al wazir> are you sure that after <77.Rxh2 Rxh2 78. e8=Q Rd2+ 79.Kc7 Rc2+ 80. Kb6 a1=Q > black wins? The board is empty. Should white run out of checks? I couldn’t see how. <arctic tern> I believe your 77.Rxh2! is drawing. |
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| Oct-15-06 |
| Confuse: does it usually take this long for a queen vs rook ending? if so i'll remember to offer a draw if im on the queen end... |
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| Oct-15-06 |
| aldehyde: black was always one move away till the final position arrived. hey white rook, twas a good job. the black queen would never forget this perspiration. |
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Oct-15-06
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| al wazir: <patrikey: are you sure that after <77.Rxh2 Rxh2 78. e8=Q Rd2+ 79.Kc7 Rc2+ 80. Kb6 a1=Q > black wins? The board is empty. Should white run out of checks?> I can't prove that it's a win, at least not without doing a lot more analysis than I want. Usually in situations like this it's possible to get a position in which the inferior side has to stop checking or else allow the superior side (black) to interpose his  with check, forcing the exchange of s. The way to do this is to maneuver the black  close to the white , while keeping the  in contact with the other two black pieces so that white can't snap it up. |
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| Oct-15-06 |
| semislav: The game is a forced draw with 81. Qb5+!. Just check it with any ending database. |
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| Oct-15-06 |
| arctic tern: <semislav><al wazir><patrikey> Interesting. I was looking at 81.Qb5+ for a while to see if there might be a perpetual to save white but I suppose it would have to be a draw by the 50 move rule. The point I was getting at with my initial post was, why play 77.e8=Q when it will lead to a theoretically won Q vs R ending for black (even if such a win is not straightforward), instead of 77.Rxh2 where white might still find a way to swindle the draw? |
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Oct-15-06
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| Albertan: Semislav you are wrong because Black cannot play 81...Qb5+ and White does not have a queen on move 81. Check the position again. |
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| Oct-15-06 |
| arctic tern: <Albertan> semislav was referring to al wazir's variation, not the actual board position. |
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Oct-15-06
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| Albertan: Oh I see arctic tern lol thanks for educating me it pays to read all the messages too :) |
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Oct-15-06
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| Albertan: <patrikey: are you sure that after <77.Rxh2 Rxh2 78. e8=Q Rd2+ 79.Kc7 Rc2+ 80. Kb6 a1=Q > black wins? The board is empty. Should white run out of checks?> As semislav correctly pointed out,
according to endgame tablebases that position is a draw if White plays and only plays 81.Qb5+ (then Black must play 81...Ka2, 81...Ka3 or 81..Kc3 (the other move 81...Kc3 leads to a checkmate in 31 moves if played correctly). |
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Oct-15-06
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| al wazir: <semislav, Albertan>: Thanks. I was wrong. Your observation casts an interesting sidelight on the game of chess. I can't use tablebases in a game, I won't study them (I'd rather study string theory or the Congressional Record), and even if I did I couldn't memorize all that stuff -- it would be like memorizing logarithm tables. Practically speaking, even GMs can't memorize all the tablebases they might conceivably need for play OTB. So what significance do they have? I'm tempted to say, none. But maybe someone can give a better answer. |
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Oct-15-06
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| artemis: al wazir: Ignoring their uses in computers, so that they can give an instant analysis of a position, they do have some value. Apparently, endgame tablebases have allowed GM's to learn more about the geometries on a chess board (they never read Euclid apparently;)), so that they have re-evaluated Queen endings, and also some complicated rook endings. I am nowhere near good enough to appreciate it, but apparently, there are some patterns that can be learned from them. |
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| Oct-15-06 |
| capablancakarpov: <MarioBalibrera> Check those Gelfand vs Svidler, 2001
V Achenbach vs Yusupov, 2000 |
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Oct-16-06
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| kevin86: This is one of the rare cases where it was a benefit to have a pair of rook pawns. White looked like the hound chasing two rabbits at the same time. |
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| Oct-17-06 |
| semislav: <MarioBalibrera> I believe this game was also a forced win S Nadir vs I Labib, 2001 |
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| Oct-20-06 |
| MarioBalibrera: <capablancakarpov>, <semislav> thanks ;-) |
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Jul-11-08
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| 4tmac: 77.RxP!! is a very pretty save by perpatual. With blacks pieces on the edge of the board (unable to help his KING) the white queen can keep checking away but care is required. A line I like goes: 77.RxP!! RxR 78. P-e8=Q R-d2+ 79. K-c7 R-c2+ 80. K-b7 P-a1=Q 81. Q-b5!! K-a2 82. Q-a5+ K-b1 83. Q-e1+ R-c1 (black sets a trap) 
click for larger view (from here on any move with a !! is an "only move to draw") 84. Q-e4+!! K-b2 85. Q-e2+!! <OR> 84. Q-e4+!! K-a2 85. Q-a5+ K-b2 86. Q-b5+ (Q-b6+) BUT Q-b4+ and Q-e5+ LOSE) |
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