Imagist: In a teaching game a while ago, my teacher (Yilun Yang) said that the ponnuki is small, but this joseki is okay for black because of a huge endgame followup starting at a which allows black to live in the corner without damaging the outside. However, I don't remember what that followup is, and I seem to have lost the SGF. Does anybody know what the followup is?
I seem to remember that the followup starts like this, but this may or may not be right. There also may be a ko involved (my memory of this is poor).
Bob McGuigan: In order for Black to use this aji he needs to play the marked stone :
This is a fairly urgent move for Black. White usually responds, but for simplicity White's response is omitted.
After the marked Black stone is in place then your followup is the correct start:
The stone gives force to since if White saves the stone in atari by extending with , is atari.
So it would usually go like this:
creates the ko you remembered.
White may also capture with instead of extending, again with ko possibilities:
Essential Joseki, page 191, indicates that when Black has reinforcement on the left, such as the marked Black stone , then pushing from behind at is good. After the invasion of the corner by Black at , White finds himself in a position that is hard to accept.