Capture two, recapture one
... and recaptures the stone.
is a legal move even if played immediately after .
The position (Dia. 1) is a 2 point ambiguous endgame. The value and timing is similar to that of ordinary 2 point gote endgames.
There are three possible lines of play:
- White connects - score: 0 points.
- Black captures two (Dia. 2), White recaptures one (Dia. 3) - score: 1 point.
- Black captures two (Dia. 2), Black connects - score: 3 points.
If the score of the third outcome was greater than 3, it would be sente. If it was less than 3, it would be gote with gote follow-up. However, the actual value is exactly on the limit, which makes it ambiguous.
After black captures (Dia. 2), the position has a count of 2 (the average score of the two possible continuations). This means, the initial move and the follow-up (in case black moves first) both have a value of 2 points.
Since the value of the follow-up is exactly the same as the value of the initial move, white will usually respond to the black capture as shown in Dia. 3.
In terms of endgame, the following position is equivalent to "Capture two, recapture one" (Dia. 1).
There are a lot of situations where this sequence is a possible variation, the consequences of which are easily overlooked. An example:
This is a line easily visualized and often played by both players if they fail to see the meaning of this shape.