BQM 439

  Difficulty: Intermediate   Keywords: Shape, Tactics, Question

fractic: In a recent game I got caught by the following move which I didn't know.

[Diagram]
corner  

fractic: It started innocent enough but I had never seen W1 before. Here is the game continuation which was very bad for me.

[Diagram]
W9 at W3  

fractic: White played a two stone edge squeeze after B2 but I couldn't find a better move for B2.

[Diagram]
continuation (B3 connects)  

fractic: I continued by cutting at a. It ended with white getting the whole corner and a big wall by capturing black+circle in a ladder. How could I have prevented this?


[Diagram]
corner  

Andy Pierce: How about this B2? You have a friend with black+square, so head for your friend. If white can't kill black in the corner, it's very bad for white.

[Diagram]
b lives  
[Diagram]
b escapes  

fractic: This looks much better for black. Thanks :)

Bill: This looks horrid for Black to me. black+circle is terrible shape.


[Diagram]
Better shape?  

fractic: How about B4 like this? If W5 then black has much better shape.

Bill: The exchange, black+circle - W3, is still bad.


[Diagram]
Problematic  

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 black+circle, which is too passive.


[Diagram]
White struggles.  

fractic: If White puts up more resistance with W5 then B6 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.


[Diagram]
corner  

At B3 and B5 there are opportunities to stop the squeeze.

fractic: (...) thanks for the advice (...).

[Diagram]
No squeeze  

Bill: (Later comment than below.) Avoiding the squeeze is very important. This looks playable. :)


[Diagram]
Black lives in the corner  

Bill: Black does not want to allow the squeeze. White's stones are divided.

Andy Pierce: To be fair, the shape of black+circle here isn't great either. :) Did black go wrong earlier than W1?

Bill: black+circle is part of an effective cut, by contrast with the empty triangle in the b escapes diagram above.

[Diagram]
Black lives in the corner  

Andy Pierce: How about B10 here instead? Maybe not so good, since white gets a in sente, whereas B10 above ends most of the aji in the corner, although I think white still gets some play on the left.

[Diagram]
Imamura Toshiya - Kobayashi Koichi 1999  

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.

[Diagram]
Hane, hane!  

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 black+circle 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.


BQM 439 last edited by Dieter on November 18, 2008 - 16:23
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