8.1 Opposition against Opposition 1
There are a lot of definitions of the term opposition in chess literature, for example:
The two kings are in opposition, if they are placed on the corners of a rectangle with all corners of the same color.
(original german version: s. Bönsch, Schachlehre, p. 181) Die Könige stehen in Opposition, wenn in dem Rechteck, dessen Ecken die Könige besetzen, alle Ecken von derselben Farbe sind.
What is the use of this definition? Is it possible to formulate a rule, which works for more than a single pawn endgame with a white pawn on the 6-th (or a black pawn on the 3-rd) row?
Let´s try it for a pawn ending with two black and one white pawn as shown in diagram 1
The crucial question is whether Black has a move with his king which conservs the value of the position and takes the opposition!
If the last move leading to diagram 1 was 1...Kf5, then the decision to take the opposition was at least no error.
Moving the two kings across the board with the white king as the leading piece leads to the following colored diagram:
Diagram 2 shows that White has only a draw, if his king is placed on one of the squares a6-e6, a5-f5, a4-g4, h3 or g6. White draws also with hie king on f6. But in this case the right to move can´t change to Black.
8.2 Opposition against Opposition 2
Is it correct to take the opposition in all other cases? No!
Diagram 3: To take or not to take opposition: Black to move - yes, Black wins! White to move - no, White can draw!.
Diagram 3: If Black takes the opposition, he wins the won position. There is no other winning move. If it is White to move, 1 Kg4 looses. But White has a single move to draw: 1 Kf4! White has not to be afraid giving Black the chance to take the opposition with 1...Kf6, it does not help Black to win! There are no winning moves (in drawn or lost positions)!
Diagram 4: To take or not to take opposition: Black to move - no, Black wins! White to move - no, White has a draw!
Diagram 4. a (=/+)-position: If Black plays 1 Kg6, he is lost. Taking the opposition is an error. But Black can win - there are winning moves in won positions - if he plays 1 Ke5 or 1 Kf7. The last move is a little bit slower, it takes Black 31 instead of 23 moves to mate White! If White takes the opposition with 1 Kf4, he is lost. White has to play 1 Kh5 in order to draw!
Diagram 5: Taking or not taking the opposition: Black to move - no, Black wins; White to move is lost
Diagram 5: If Black plays 1 Ke6, he is okay. But it looks strange (Oops ... ! Oops has fallen back into the language of commentators!). Black can try 1 Kf6 - in order to take the diagonal opposition. But then he is lost. But with the anti-oppositional move 1 Kf5 is a winning move, so as 1 Ke7. The last move is a little bit slower: 31 instead of 17 moves to mate White. So White is without any chance in diagram 5. It is a (-/+)-position, i.e. White´s only moves are loosing moves. Taking the opposition doesn´t change this situation.
The above examples show, that it is not easy to formulate proofable rules for a large group of chess positions. Even for positions with 6 pieces. To be close to your own pawns seems to be the better rule than taking the opposition in pawn endgames of the type just shown.
Fundemental Positions and Color Codes
Color codes for the Representation of Positional Types without taking care of the right to move
List of examples