Joseki-related life-and-death example 11
After the double approach ( stones), - are joseki.
If the corner group later gets surrounded ( stones to indicate this), and the top side is white ( stones to indicate this) the moves - are sente.
If black plays tenuki after , how can white kill?
and are not hard to find, but the tesuji sequence of - is quite nice.
Now black can try a number of things.
Simply connceting is pointless. and create a bulky five.
attempts to create liberties along the top, to prevent white from cutting at a.
But still, after -, a bulky five is formed. Black is dead (Note that black should not be able to make eyes along the top, hence the requirement of the stones.
This doesn't work either. After , black is captured. The same refutation works for at a or b.
With here, black is trying to tempt white to cut. But is simple and correct. If black plays to prevent the bulky five, cuts with atari, and black is captured in a ladder.