In chess, opposition (or direct opposition) is the situation occurring when two kings face each other on a rank or file, with only one square in-between them. In such a situation, the player not having to move is said to "have the opposition" (Flear 2004:12). It is a special type of zugzwang and most often occurs in endgames with only kings and pawns (Flear 2000:36). The side with the move may have to move the king away, potentially allowing the opposing king access to important squares. Taking the opposition is a means to an end (normally forcing the opponent's king to move to a weaker position) and is not always the best thing to do.
There are extensions of direct opposition, such as diagonal opposition and distant opposition, which can be conducive to reaching direct opposition. All three types may be referred to simply as opposition if the type is unambiguous in context.
|This article uses algebraic notation to describe chess moves.|
Direct opposition is a position in which the kings are on the same rank or file and they are separated by one square. When the term opposition is used, it normally refers to direct opposition.
In this diagram, the player whose turn it is not to move has the opposition. If it is Black's turn to move, White has the opposition and wins (Flear 2004:23). (See King and pawn versus king endgame.) If it were White's turn to move, Black would have the opposition and the position would be a draw.
In the 1959 game between Svetozar Gligorić and Bobby Fischer, Black can draw by keeping the white king from getting to any of the key squares (marked by dots). This is accomplished by not allowing White to get the opposition, and seizing the opposition if the white king advances.
- 57... Kb8!
This waiting move is the only move to draw. (In the actual game the players agreed to a draw at this point.) Other moves allow White to get the opposition and then get to a key square. If the white king gets to a key square, White wins. For example 1... Kb7? 2. Kb5, then the black king moves and the white king gets to a key square and then wins by forcing promotion of the pawn.
- 58. Kc5 Kc7
- 59. Kb5 Kb7
- 60. Ka5 Ka7 and Black draws. In this sequence, any other moves by Black lose (Müller & Lamprecht 2007:20), (Fischer 2008:86).
Opposition along a diagonal (instead of a rank or file) is called diagonal opposition. Sometimes diagonal opposition is used to achieve direct opposition. An example is the position in the diagram on the left, with Black to move. White has the direct opposition in this position, but it does him no good because his king cannot attack the black pawn after the black king moves away. White needs to achieve direct opposition closer to the pawn.
- 1. ... Kf8
- 2. Kd6 and White has the diagonal opposition (diagram on the right).
- 2. ... Ke8
- 3. Ke6 White now has direct opposition on a useful square, and White wins:
- 3. ... Kf8
- 4. Kd7 Kg8
- 5. Ke7 Kh8
- 6. f6 gxf6
- 7. Kf7 or 7. Kxf6 win for White (Flear 2004:33).
Distant opposition is a position in which the kings are on the same rank or file but are separated by more than one square. If there are an odd number of squares between the kings, the player not having the move has the (distant) opposition. As with diagonal opposition, it is often converted to direct opposition, as in the diagram on the right (Capablanca & de Firmian 2006:41):
- Ke2 (White takes the distant opposition) ... Ke7
- Ke3 Ke6
- Ke4 (takes the direct opposition, and now Black must step aside) Kd6 (... Kf6 allows the corresponding Kf4!)
- Kd4! (Kf5 would lead to both pawns queening) Kc6 (... Ke6 5. Kc5 and is way ahead in the queening race)
- Ke5 (and White has a choice of which pawn he wins, and then use this as the outside passed pawn unless he can promote it directly)
Black can be tricky and try
- ... Kf8 and if
- Ke3 then Ke7 and now Black has the distant opposition and draws. Similarly 2. Kf3 Kf7.
White instead should remember that the aim of the opposition is to penetrate, so step sideways and forward with
- ... Kf8
- Kd3! Ke7 (otherwise White penetrates with Kc5, and will win a queening race)
- Ke3! (White again has the distant opposition and transposes into the main line)
This position is very similar to the previous position. White is to checkmate, moving the rook only once in the process. The main line is:
- Kg2 (taking the distant opposition) Kg7
- Kg3 Kg6
- Kg4 Kh6 (and since the black king has been forced to step aside to the h-file, White can now penetrate on the f file)
- Kf5! Kg7 (... Kh5 5.Rh1#)
- Kg5 Kh7
- Kf6 Kg8 (... Kh8 7. Kf7 Kh7 Rh1#)
- Kg6 Kh8
Again, if Black is tricky, he can try
- ... Kh8 (again, White penetrates)
- Kf3! (Kg3 Kg7; Kh3 Kh7 give Black the distant opposition) Kg7 (Kh7 3. Kf4!)
Yuri Averbakh pointed out that the opposition is a means to an end; the end is penetration to a key square (Averbakh 1987:5). This can be a square in front of a pawn, so the king can lead it to the queening square, or into a critical zone to win an enemy blocked pawn.
In the diagram, White should play 1.Kc5; taking the opposition by 1.Ke4 draws.
The second position shows a simpler example. If White takes the opposition with 1.Ke6 he makes no progress. The winning move is 1.Kc7 (see king and pawn versus king endgame).
- Chess endgame
- Corresponding squares
- Key square
- King and pawn versus king endgame
- Averbakh, Yuri (1987), Comprehensive Chess Endings: Pawn Endings, vol. 4, Pergammon, ISBN 0-08-026906-0
- Capablanca, Jose; de Firmian, Nick (2006), Chess Fundamentals (Completely Revised and Updated for the 21st Century), Random House, ISBN 0-8129-3681-7
- Fischer, Bobby (2008) , My 60 Memorable Games, Batsford, ISBN 978-1-906388-30-0
- Müller, Karsten; Lamprecht, Frank (2007), Secrets of Pawn Endings, Gambit Publications, ISBN 978-1-904600-88-6
- Nunn, John (2007), Secrets of Practical Chess (2nd ed.), Gambit Publications, pp. 113–18, ISBN 978-1-904600-70-1