Sealing in by striking at the waist
Black threatens to cut White apart. By capturing firmly with
White keeps her stones connected, but now Black can play
in sente, sealing White in.
Related questions
Should White play the intermediary atari?
If this happens, White at a is less powerful (because assists Black at b).
Not entirely clear, though.
If the fighting is intense, White might prefer this. In principle is bad style (rather than taking
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 added everywhere?
If is actually going to be played, therefore, it looks as if playing
atari first will sometimes be correct.
tapir: I can't believe that 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.
Black is O Meien, White is Lee Sedol. White is sealed in and proceeds at a to make life for his stones. resists against the above mentioned technique: