High invasion of mixed three space extension
is not as common as the invasion at a (see low invasion of mixed three space extension), because Black's response at a will usually connect the two black stones together. Alternatively, Black may choose to attack
with b.
alone is usually not a good play: usually
is used in conjunction with a white stone at c.
Trying to cut with is unreasonable. In this diagram, White has achieved nothing. If
is played at
, Black will cut at
.
Trying to live this way is too low for white, and tends to give away too much influence to Black. Later, Black a will capture .
Normally the wedge at is too big a sacrifice because it gives Black a ponnuki, but in some specific situations separating
may be worth the sacrifice. In some other situations
may be played at a, but Black b can seal the white group in.