( 980)

(Referenced by 152)

Instead, White will exchange two pairs of / .

But now, White's centre group has six effective liberties left (3 * w, 3 * c), at a moment when Black must connect the hanezeki's tail, which is a disaster for Black. So what went wrong with the transformation?

Nothing, we are simply not finished yet. We can shift Black's stone , which occupied a shared liberty, to the outside of White's centre-group, to give Black's group an additional liberty.

Black's moved stone is at now. Additionally, we added a pair of / stones to reach the moment, when White's centre group has five effective liberties left (w, 4 * c), i.e. the moment when White will capture the ko "late".

The position is similar to that of the main line, as far as the relationship of liberties is concerned. Black will need one external ko-threat to win the ko-fight.

:
In this variation, however, Black has the required external ko-threat ( to are played at an appropriate moment earlier) available. Please note that White does not have any valid ko-threats here.

Black's atari at simultaneously reduces White's -group to only four liberties (x), less enough to lose the semeai with Black's connected group on the lower edge. So White is forced to answer locally. Additionally we have to record that it would not really help White to pre-empt Black's ko-threat on the left side, because Black has another ko-threat available, the atari at .

This implies that White cannot start the ko-fight in the upper right "late", but must do so "early", to exhaust Black's ko-threats.

:
Black's group is below the Punishment Semeai Liberty Level, so Black is unable to occupy another shared liberty, with a move at . His only option remaining is to use the atari of in the hanezeki as a ko-threat.

:
White covers her weakness on the upper edge.

:
The point of is still unavailable for Black, due to White's threat of the Punishment Semeai, so he has to connect the hanezeki's tail.

Ko: ; ; ;

:
Black uses his remaining "quick" ko-threat in the nakade on the left side. If White had used her move at (= ) to pre-empt Black's ko-threat in the nakade, e.g. with a move at , Black would give atari at , instead, achieving the same result.

White's -group has five liberties left, so the "slow" in the nakade is no valid ko-threat for Black. The same is true for on the upper edge, because White's centre group still has four liberties.

:
Black re-captures the ko for the last time, and will win the game.

After Black's move at , it is simply no valid option for White to start the ko "late".