Sealing in by striking at the waist

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    Keywords: Tesuji, Shape
[Diagram]

Black can set up a useful sequence by striking at the waist of the keima.

[Diagram]

Black threatens to cut White apart. By capturing B1 firmly with W4 White keeps her stones connected, but now Black can play B5 in sente, sealing White in.


Related questions

Should White play the intermediary atari?

[Diagram]

Is atari good here?

This is a typical 'good style' question. Here the answer seems fairly clear.

[Diagram]

White has lost something

If this happens, White at a is less powerful (because B2 assists Black at b).



Not entirely clear, though.

[Diagram]

If White want this ...?

If the fighting is intense, White might prefer this. In principle W5 is bad style (rather than taking black+circle off immediately). Sometimes White might want to form one immediate eye; and leave the cutting point at c. In that case it could be true that the aji of White at d later is worth having; and more important than the direction of the bend at a.

tapir: I doubt White want to give away sente like this. Especially if fighting is intense. Why is this W5 added everywhere?

If W5 is actually going to be played, therefore, it looks as if playing W1 atari first will sometimes be correct.


tapir: I can't believe that W6 creating a cutting point with a clumsy shape is any good. Isn't direct capturing better? Now white has some reason to expect she will be the one playing at a etc.

[Diagram]

I would expect this.


Pro example

[Diagram]

Moves 45 to 51

Black is O Meien, White is Lee Sedol. White is sealed in and proceeds at a to make life for his stones. W4 resists against the above mentioned technique:

[Diagram]

Moves 45 to 51

Regardless the fact that W4 makes a ladder that doesn't work, Black connecting with B5 and B7 is probably unbearable.


Diagram from Tesuji Dictionary

[Diagram]

From Fujisawa Hideyuki's Tesuji Dictionary (vol. I, p.63)


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