In the absence of the black stone on the side at the circled point, is joseki: a double kakari here isn't an overplay.
White may also invade the corner at the 3-3 point for : see below.
Then matters can be expected to take a definite course: up to here is a very well-trodden path in joseki.
After that Black a and b are joseki continuations. Black c is no longer: this variation died a sudden death in 1992 amongst the pros. Klaus: Does annyone know why c is bad ?
To play high is also possible. Then
is still good shape. Next White at a may be the expected answer; but White directly at b has been played consistently enough in pro games since 1994.
If White invades the corner to get settled, up to is an invariable joseki.
Bill: Not invariable.
can also be at
.
Most likely, Black nows plays tenuki. There is some question about Black's play here, if Black does add a stone.
Adding is taught as honte.
Adding is normally treated as sente by White, because Black's move next at a feels severe.
Therefore the exchange - White a is often seen here before Black plays away. Black is trying with the play at
to confine the
stone on a larger scale. Naturally it still has plenty of aji.
It is forbidden to strong players to think in terms of adding both and
, though. This is Overconcentrated shape. See more at Honte / Discussion.
A compromise is for Black to play at a. This may have been invented by Kubomatsu in 1931. It gives Black a good next move here at b.
Author: Charles Matthews