In this article of Go World, Ayumi Suzuki explains some middle game joseki.

She takes a look at the sanrensai opening and explains that the point A is a key point for invasion (although it may be a little early to invade in this situation):



Attaching on top is natural for black. Now the question is in which direction should white extend. Extending upwards leads to this sequence:



This is quite a painful shape for White.

So the extension of White 1 in the other direction is right, after which the connection of Black 2 is correct (... explanation omitted here ...):



The point of A is open this time, so Black can't attach at B.

This sounds as if it is obvious - but I can't see it. Any ideas?

_________________
Stay out of my territory! (W. White, aka Heisenberg)

The book "Get Strong at Invading" contains a lot of this kind of joseki. Still on my to-do-list.

I believe the reason why black can't attach at B is because is now sente (and living) since black has so many cuts in his wall.

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . X . O . O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . X , . . . . . , . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . X . . . . . . . . . . . X W . . |
$$ | . . . . . . . . . . . . . . X O O O . |
$$ | . . . , . O . . . O . . . . . X X X . |
$$ | . . . O . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

hum~~ no!
below shape i think white will cut then black is in trouble. (dont ask me how..but it is just a feeling)

Click Here To Show Diagram Code

[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . X . O . O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . X , . . . . . , . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . X . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . X O O O . |
$$ | . . . , . O . . . O . . . . 1 X X X . |
$$ | . . . O . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

_________________
"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson