Karl Knechtel: The eye at a is already secured. White needs to make one in the space around b.
First, White chases Black around. If is played elsewhere, then White will play at
to seal off the second eye. Similar reasoning is applied for
.
threatens capture of more than enough eye space, so Black must capture.
threatens to capture again so Black fills in, but it's a connect-and-die -
finishes the job since Black can't escape.
splice: Small technicality. Karl's comment: " threatens capture of more than enough eye space ...". As far as I can read, anything less will leave White with one eye. To wit:
So playing until the black stone is hit is not more than enough eye space, it's actually just enough. At least, the way I see it :)
unkx80: In the diagram entitled "Not enough", is wrong, but
is also wrong.
lives.
aigo: Following the same line of logic, is another mistake, it should go where
is to make an eye instead of capturing the black stone.
unkx80: Yes.
should be played here. Subsequently, if White a, Black throws in at
and the eye becomes a false.
This way White has just enough space to make a second eye.