Capture two, recapture one
The phrase capture two, recapture one describes the sequence below. Note that this is not a ko.
captures two White stones...
... and recaptures the
stone.
is a legal move even if played immediately after
.
Also, this sequence gives no eye to Black.
There are a lot of situations where this sequence is a possible variation, the consequences of which are easily overlooked. An example:
Black to live. The combination of the marked shape with the 1-2 point is very common in life and death problems. Yet our desire to atari may overcome us:
This is a line easily visualized and often played by both players if they fail to see the meaning of this shape.
White plays and recaptures a stone with
at
after
takes two stones. Black is dead.
Black's correct move is the 1-2 point. White can't play at a due to shortage of liberties. If White next b, Black a gives life.
See also: