fractic: In a recent game I got caught by the following move which I didn't know.
fractic: It started innocent enough but I had never seen before. Here is the game continuation which was very bad for me.
fractic: I continued by cutting at a. It ended with white getting the whole corner and a big wall by capturing in a ladder. How could I have prevented this?
Andy Pierce: How about this ? You have a friend with , so head for your friend. If white can't kill black in the corner, it's very bad for white.
fractic: This looks much better for black. Thanks :)
Bill: This looks horrid for Black to me. is terrible shape.
fractic: How about like this? If then black has much better shape.
Bill: The exchange, - , is still bad.
Bill: Even eliminating that bad exchange, we can make a better shape for Black. (I have added a stone for White.) But isn't this still problematic for Black? Isn't Black overconcentrated? The problem goes back to , which is too passive.
fractic: If White puts up more resistance with then still works. If White plays c black can play a or directly b. If White plays atari at a instead and then defends at c Black b captures three white stones.
At and there are opportunities to stop the squeeze.
fractic: (...) thanks for the advice (...).
Bill: (Later comment than below.) Avoiding the squeeze is very important. This looks playable. :)
Andy Pierce: To be fair, the shape of here isn't great either. :) Did black go wrong earlier than ?
Andy Pierce: How about here instead? Maybe not so good, since white gets a in sente, whereas above ends most of the aji in the corner, although I think white still gets some play on the left.
Dave: The only real example I found. Note there are nearby stones such as those marked that may have led Black to try this line.
Bill: The proverb says to Hane at the head of two stones. In this position Black can hane at a or White can hane at b. Both look strong, especially b, since it weakens Black's stones so much. If a does not work, Black almost has to play b to prevent White from playing there.
BTW, hasn't this shape, with a different position, been discussed here this year?
fractic: I don't know whether it has been discussed here or not but I looked at Kogo's joseki dictionary. For some other pincers this move is mentioned. But after Black a White b White does not extend the stone at b after the atari. Probably because the variation you gave above.