Gokyo Shumyo, Section 1, Problem 33 / Solution

Black lives  

is tesuji. It is the effective use of the belly attachment suji. It deals with two problems simultaneously, namely White's cut at a and White's watari at b.

Main line  

may be unexpected resistance. makes miai of a and b.

Continuation 1  

After , the circled points show Black's liberties (four). Even if White effectively captures the stones, Black connects at a and White has three liberties : two inside the eye, and one internal, which Black cannot count. (See Richard Hunter's theory on Counting Liberties.)

Continuation 2  

After , White is caught in a shortage of liberties, so White cannot play at a.

Approach ko  

White's best resistance is this line, leading to two-move approach ko. (In practice, it may not be worth the effort because the line loses some territory points first.)

2. The connection  

Caution! Black is not alive in sente! He has to answer. If not:

Beware of the belly  

White's belly attachment makes ko. Black cannot answer with at , because at will then reduce him to one eye.

Wrong 1  

The vulgar (crude) move at provokes a forcing magari at , giving White the time to play atari with .

Wrong 2 (at move 5)  

If Black hane at , threatens to make two eyes, and makes it ko.

Wrong 2 (at move 5)  

If Black turns at , White plays atari from the other side (again threatening to make two eyes) and then captures two stones with . Black can neither play at a nor at b, because of shortage of liberties.