Protect Both Sides in the Corner

The hane-connect in this diagram is a well known endgame play.

White will now usually defend at a, b, or perhaps c.

However, in the corner, there is sometimes a better option.

Setup

Consider this corner.

White plays hane and connects, and black must defend the cut now.

How?

Wrong answer

is wrong, as is the move at a.

After , white can play another hane-connect, -, in sente. Black needs (or b) to defend again.

Right answer

The right answer is to play . This not only defends against the cut at a, it also makes the hane at b gote for white.

With , black protects both sides with one move.

Caution

The technique shown only works in limited situations where is not too far away from the cut, and is close to the other hane.

Some examples where it fails:

Note the tesuji !

at a, at b

It is also, of course, important to check for other weaknesses related to the cut, such as this one.