(Referenced by 225)

: ( 72)
Black spoils the shape of White's group on the upper edge, before continuing with the Crosscut Sequence.

:
!!! We use this sub-variation as an example to show that it will not really help Black to keep his three forcing moves , , and , in the upper right corner (as well as the throw-in of in the centre) in reserve, for the later application as ko-threats. !!!

This is also shown in the chapter about the historical development of our amateurs' knowledge ( 864).

Ko: ; ; ;

: (A 85)
White is able to play this protective move on the left side. It reduces the amount of Black's potential ko-threats in the nakade to only two.

Doing without a protective move like this is possible for White, but the ko-fight will become unnecessarily protracted.

:
White starts the ko-fight "early".

Ko: ; ; ; ; ; ; ; ;

:
This move is gote, but it will enable ko-threats at , and .

:
Black will not create more valid ko-threats in the nakade by giving atari with a move at , instead.

:
White re-captures the ko for the last time, and Black faces a dilemma now: He has run out of valid ko-threats.

All of White's -groups on the left side have two liberties more than Black's nakade-stones . This means that there are no valid ko-threats in the nakade any more.

White's centre group has six effective liberties (3 * w, 3 * c) left. Connecting the hanezeki's tail makes no sense now, because Black's connected group on the lower edge will have five effective liberties only. Black's suicidal ko-threat at is no option either. It would hasten the end, due to the loss of an approach-move liberty for Black's connected group.

:
So Black sets his hopes on further occupying liberties of White's centre group.

:
White establishes a temporary seki in the upper right, and the centre. Black is unable to give atari at .

Thereafter, she will capture Black's connected group on the bottom, winning the game.