The opposition, and how to count who has it
Kings cannot touch, so they push each other about at a distance. In an endgame with almost nothing left, that shoving match is the entire game.
- Who has it The player who does not have to move
- How to count An odd number of squares between the kings
Two kings can never stand next to each other, and that simple rule turns into a whole technique. When the kings face each other with one square between them, the player who has to move must step aside and let the other king past on one side or the other. The player who does not have to move is said to have the opposition.
In a king and pawn ending this is usually the only way to make progress, because your king cannot walk through the enemy king and there is nothing else on the board to threaten. It is zugzwang in its purest form: the obligation to move is the thing that loses.
The position everything else is measured against
Black to move, and the king has exactly two squares. Both of them step aside, and White takes the one Black gave up.
Black gives way on the kingside, so White goes the other way.
1...Kf8 2.Kd7 Kf7 3.e6+ Kf6 4.e7 Kf7 5.e8=Q+
A new queen, with check. Note that this position is actually winning for White whoever is to move, because the king is already in front of the pawn on the sixth rank. That is what makes it worth fighting for.
One rank further back, and the move decides everything
Same material, one rank back, White to move. Black has the opposition here and holds the draw. The defensive rule on show: retreat straight back, to the square in front of the pawn, never to one side.
1.Kd5 Kd7 2.e5 Ke7 3.e6 Ke8 4.Kd6 Kd8 5.e7+ Ke8 6.Ke6
Stalemate. Black is not in check and has no legal move at all, so the game is drawn. Two positions, the same three men, and the only difference was who had to move first.
The practical version of all this is short. In a king and pawn ending, walk your king in front of your pawn rather than behind it, and try to arrive there with your opponent to move. A king in front of its pawn on the sixth rank wins on its own, with one exception: a rook pawn, where the defending king reaches the corner and cannot be evicted from it, which is the simplest fortress in the game.
And do the counting before you touch anything. The opposition is usually decided several moves before the kings are anywhere near each other, which is why so many drawn pawn endings are thrown away by a king move played instantly because it looked natural.
How to count it
- Kings on the same file, rank or diagonal with an odd number of squares between them: the player who does not have to move has the opposition.
- One square between is direct opposition. Three or five is distant opposition, and it works the same way, so keep the count odd as you walk towards each other.
- With a pawn on the board, your target is the square in front of it on the sixth rank. Get there and the opposition stops mattering.
- When you have the position you want but the wrong side to move, the fix is triangulation.
- More of this shape of ending is at pawn endgames.
Questions people ask
How do you know who has the opposition?
Count the squares between the kings along the file, rank or diagonal they share. If that number is odd, whoever is not to move has the opposition, and the other king will be forced to give way sooner or later. If the number is even, the player to move can take the opposition by stepping towards the other king and making it odd.
What is distant opposition?
The same standoff with three or five squares between the kings instead of one. It matters because the kings are often nowhere near each other when the critical decision is made. If you keep an odd number of squares between the kings as they approach, the direct opposition will be yours when they finally meet, and the whole fight is decided long before that.
Related
Opposition sits under Endgame words in the reference. Nearby: