Benutzer:Der-Wir-Ing/Opposite-colored bishops endgame
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Vorlage:Chess notation The opposite colored bishops endgame is a chess endgame in which each side has a single bishop, but the bishops reside on opposite colored squares on the chessboard, thus can not attack or block each other. Without other pieces (but with pawns) these endings are notorious for their tendency to result in a draw. These are the most difficult endings in which to convert a small material advantage to a win.
Many players in a poor position have saved themselves from a loss by trading down to such an endgame. They are often drawn even when one side has a two or even three pawn advantage since the weaker side can create a blockade on the squares which his bishop operates on. About half of the endings with a bishop and two pawns versus a bishop on the opposite color are drawn Vorlage:Harvcol. (By contrast, over 90 percent are won if the bishops are on the same color.) Interestingly the weaker side should often try to make his bishop bad by placing his pawns on the same color of his bishop in order to defend his remaining pawns, thereby creating an impregnable fortress Vorlage:Harvcol. The attacker should generally put his pawns on squares of the opposite color as his bishop to prevent a blockade Vorlage:Harvcol.
Bishop and pawn versus bishop Bearbeiten
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The attacker's bishop is practically useless and the defender can normally draw if his king can reach any square in front of the pawn that is not of the color of the attacking bishop; or if his bishop can permanently attack any square in front of the pawn Vorlage:Harvcol. These endings are trivially drawn 99 percent of the time Vorlage:Harvcol.
Bishop and two pawns versus a bishop Bearbeiten
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About half of these positions are drawn. In most other endings, a two pawn advantage is usually an easy win. For example, if the bishops were on the same color, 90 percent of the positions would be wins.
There are three general cases, depending on the two pawns. In most endings, a pair of connected pawns have the best winning chances, but in these endings a widely-separated pair of pawns have the best chances.
Doubled pawns Bearbeiten
With doubled pawns the position is a draw if the defending king can reach any square in front of the pawns that is not of the color of the attacker's bishop. The second pawn on the file is of no help, so this is like the ending with only one pawn.
Isolated pawns Bearbeiten
With isolated pawns (on different files), the outcome depends on how widely separated the pawns are. The more widely separated they are, the better the winning chances Vorlage:Harvcol. The rule that holds in most cases is that if only one file separates the pawns the game is a draw, otherwise the attacker wins. The reason is that if the pawns are more widely separated, the defending king must block one pawn while his bishop blocks the other pawn. Then the attacking king can support the pawn blocked by the bishop and win the piece. If only one file is between the pawns, the defender can stop the advance of the pawns. See the diagram Vorlage:Harvcol. If three files separate the pawns, they normally win Vorlage:Harvcol.
Even that is only a rule of thumb, however, as N. Miller-Saidy, American Open 1971 shows. White resigned because he knew a "rule" articulated by Fine in the first edition of Basic Chess Endings: "If the pawns are two ore more files apart, they win." (ADD CITE TO Fine, Basic Chess Endings (1941), p. 179) Since here three files separate the pawns, White assumed his position was hopeless. In actuality, however, the position is a fairly straightforward draw, since "White's King has such a powerful active location that he can keep Black's King from penetrating either side of the board." CITE Edmar Mednis, Practical Bishop Endings, Chess Enterprises, 1990, p. 96. Play might continue 1.Bh3+ Ke7 2.Bg2 Kf6 3.Bh3 Kg5 4.Bg2 Kf4 5.Kc4! Bd4 6.Kd3 Bg1 7.Bc6 Kg4 8.Bg2! Bf2 9.Kc4! Kf4 10.Kd3 Ke5 11.Kc4, when, "Clearly there is no way for Black to break the blockade." Mednis, p. 97
Connected pawns Bearbeiten
Positions with connected pawns are the most complex case, and the result depends on the ranks and files of the pawns and the colors and locations of the bishops. If one of the pawns is a rook pawn (on the a file or h file) the position is normally drawn. If the pawns are on the opposite color as the defender's bishop, the defender may be able to blockade the pawns and draw. If both pawns can safely reach the sixth rank, they win (if neither is a rook pawn).
The ideal drawing setup is seen in the diagram at left. Black's king (on a square not of the color of the opposing bishop) and bishop stay two ranks in front of the pawns, with both defending against a pawn advance (here d6 by White) to the same color square as the bishop. The defending bishop must maintain an attack on the pawn on the same color square as itself, so that the attacking king is not allowed to advance. If White pushes the other (unattacked) pawn, Black's bishop sacrifices itself for both pawns, with a draw. In the diagram position, Black on move passes (i.e. a waiting move that maintains the attack on the pawn) with 1... Bb8! 2. Ke4 Bc7! 3. Kf5 Bb8! and so on. White cannot make progress: 4. d6+ is met, as always, by 4... Bxd6 5. exd6+ Kxd6 with an immediate draw; 4. e6 gives Black an unbreakable blockade on the dark squares; and White can never prepare for d6+ by playing Kc5 because Black plays ... Bxe5.
A similar position with White's pawns on the sixth rank is a win because the black bishop has no room to move and maintain the attack on the pawn on d6, thus Black is defeated because of zugzwang. In the position at right, Black loses immediately. Black, on move, must give way with either bishop or king, allowing White to move e7, winning, or else play the hopeless 1... Bxd6 2.Kxd6. If White is to move in this position, he plays a waiting move such as 1. Kc6, placing Black in the same predicament (1... Ke8 2. Kc7#) Vorlage:Harvcol.
More pawns Bearbeiten
Vorlage:Chess diagram Draws are possible with more pawns. This is an example of a drawing fortress with opposite-colored bishops when three pawns behind. White simply keeps his bishop on the h3 to c8 diagonal Vorlage:Harvcol. (See Fortress (chess)#Fortress with opposite-colored bishops.) Positions with three pawns versus none are wins 90 percent of the time Vorlage:Harvcol.
Examples from master games Bearbeiten
Berger-Kotlerman Bearbeiten
Vorlage:Chess diagram In Berger versus Kotlerman, the pawns are separated by two files, but the game was drawn Vorlage:Harvcol.
- 1. Ke2 b3
- 2. Kd1 Kb4
- 3. Bh7 Ka3
- 4. Bg6 Kb2
- 5. Bf7! Ka2
- 6. Be6 Ka3
- 7. Bf5! ½-½
If 7. ...b2 then 8. Bb1. If Black keeps his king near the b pawn then White moves his king. If the king goes to g2 trying to displace the white king, White moves the bishop.
Piskov-Nunn Bearbeiten
Vorlage:Chess diagram Black has an inferior position, but he draws by exchanging queens and rooks, giving up two pawns, and reaching a drawn endgame:
- 37. Bf6 Qh5!
- 38. Qxh5 gxh5
- 39. Rxe8+ Bxe8
- 40. Be7 Bg6
- 41. Bxc5 Kf7!
- 42. Bxd4 a6
- 43. a3 Bd3
- 44. c5 Bc5
- 45. d6 Ke6
- 46. Kf2 Kd7
Vorlage:Chess diagram The blockade has been set up. Black's pawns can be protected by his bishop and White's passed pawns can't make any progress. The game continued:
- 47. Kg3 Be6
- 48. h4 Kc6
- 49. ½-½ Vorlage:Harvcol.
Nunn Bearbeiten
Vorlage:Chess diagram In this position from Nunn (a slight modification of a simultaneous game), White wins:
- 1... Be1
- 2. Kf6! Bh4
- 3. Kf5 Kd6
- 4. g3 fxg3
- 5. Bg2 Kc7
- 6. Ke5 g4
- 7. hxg4
and White wins easily by supporting the g-pawn with the king. Black loses because he cannot defend the pawn on g5 with the bishop from d8 or e7. If the black king were on b8 then 1... Ba5 would draw Vorlage:Harvcol.
Sokolov-McShane Bearbeiten
Vorlage:Chess diagram Vorlage:Chess diagram Vorlage:Clear In the game between Ivan Sokolov and Luke McShane, Black discards his pawn and goes for a stalemate defense:
- 1... c4!?
- 2. Bxc4 Kf8
- 3. h5 Ke7
- 4. Bb3 Kf8
- 5. f6 Ke8 ½-½
and a draw was agreed, because White cannot break through, e.g. 6. Ba4+ Kf8 7. h6 Bxf6 8. Kxf6 stalemate Vorlage:Harvcol.
Lautier-Rublevsky Bearbeiten
Vorlage:Chess diagram In an endgame with opposite colored bishops, positional factors may be more important than material. In this position, Black sacrifices a pawn (leaving him three pawns down) to reach a fortress.
- 1... Kf5!
- 2. Kxf7 Bh5+
- 3. Kg7 Bd1
- 4. Be7 ½-½
After 4... Be2 5. Kh6 Bd1 6. h5 Black just waits by playing 6... Be2 Vorlage:Harvcol.
"In endings with bishops of opposite color, material means NOTHING, position EVERYTHING." - Cecil Purdy Vorlage:Harvcol. Vorlage:Clear
Kotov-Botvinnik Bearbeiten
Vorlage:Chess diagram Another position illustrating the above-stated principle is Kotov-Botvinnik, Moscow 1955. Alburt writes, "Black has an extra pawn, but his opponent appears to have a reasonable blockade in place." Vorlage:Harvcol. However, Botvinnik finds a way to create another passed pawn.
- 1... g5!!
- 2. fxg5 2. hxg5 h4 3. Bd6 Bf5 4. g6 Bxg6 5. f5 Bxf5 6. Kxb3 Kg2 costs White his bishop and the game. Vorlage:Harvcol Vorlage:Harvcol.
- 2...d4+! Black must keep his b-pawn Vorlage:Harvcol Vorlage:Harvcol.
- 3. exd4 Black has gone from being a pawn up to temporarily being a pawn down, but he has a won game. If 3. Bxd4, Kg3 4. g6 Kxh4 5. Kd2 Kh3!! 6. Bf6 h4 7. Ke2 Kg2! Vorlage:Harvcol
- 3...Kg3! Not 3...Kg4? 4. d5! Bxd5 5. Bf2, drawing Vorlage:Harvcol.
- 4. Ba3 4. g6 Kxh4 5. g7 Kg4 also wins Vorlage:Harvcol. 4. Be7 Kxh4 5.g6+ Kg4 wins Vorlage:Harvcol.
- 4...Kxh4
- 5. Kd3 Kxg5
- 6. Ke4 h4
- 7. Kf3 Or 7.d5 Bxd5+ Vorlage:Harvcol.
- 7...Bd5+ 0-1
Advantageous against weak pawns Bearbeiten
Vorlage:Chess diagram In some cases with more pawns on the board, if one side has weak pawns then it is actually advantageous to the other side to have the bishops on opposite colors. In the game of Efim Bogoljubov versus Max Bluemich, 1925 (see diagram), White wins because of the bishops being on opposite colors making Black weak on the black squares, the weakness of Black's isolated pawns on the queenside, and the weak doubled pawns on the kingside Vorlage:Harvcol. The game continued: (complete game)
- 29. Kd2 Ke7
- 30. Kc3 f6
- 31. Kd4 Be6
- 32. Kc5 Kd7
- 33. Kb6 g5
- 34. Kxa6 Kc7
- 35. Bb6+ Kc8
- 36. Bc5 Kc7
- 37. Bf8 f5
- 38. Bxg7 f4
- 39. Bf6 f3
- 40. gxf3 exf3
- 41. Bxg5 Bxh3
- 42. Bf4+ 1-0
See also Bearbeiten
References Bearbeiten
- Lev Alburt: Rules? What Rules? Part I. In: Chess Life. December, 1996, S. 18–19.
- Vorlage:Citation
Further reading Bearbeiten
- Benko, Pal. "Opposite-Colored Bishops", Chess Life, Nov 2007, 56-57.