3-3 invasion, double hane divergence

[oca]

oca, you liked this post, don't forget it!

http://www.lifein19x19.com/forum/viewto ... 51#p166351

That's still in my head, and that was my first try but I did it the wrong way like that...

$$W The wrong way...
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X . |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . . a 1 . . |
$$ . . . . b . . |
$$ --------------+

Click Here To Show Diagram Code

[go]$$W The wrong way...
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X . |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . . a 1 . . |
$$ . . . . b . . |
$$ --------------+[/go]

seems like I first need to play "a" to force black to form that L+1 group (black playing at )... and only then I reduce at "b"

[EdLee]

Hi oca, yes, very Zen indeed. And very difficult to reach.
Very, very high level.

[drmwc]

Can't black actually get a ko here?

$$W Here we ko, here we ko, here we ko....
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O 2 . |
$$ . . . 5 X O 3 |
$$ . . . O O X 4 |
$$ . . . O X X . |
$$ . . . O X . 9 |
$$ . . . 1 6 7 0 |
$$ . . . . . 8 . |
$$ --------------+

Click Here To Show Diagram Code

[go]$$W Here we ko, here we ko, here we ko....
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O 2 . |
$$ . . . 5 X O 3 |
$$ . . . O O X 4 |
$$ . . . O X X . |
$$ . . . O X . 9 |
$$ . . . 1 6 7 0 |
$$ . . . . . 8 . |
$$ --------------+[/go]

This seems to work. There are other variations, but they are all ko-like. The key point is the stone captured in the ladder gives black aji he doesn't usually have, so 4 becomes sente.

For the avoidance of doubt:
Getting a result like this from a 3-3 invasion is a miserable failure for black, and he should have played differently earlier on. But once in this mess, his or her corner can scramble a ko.

[oca]

I was white in that game and black won, mainly because this corner actually went to a ko. I decided to take that ko to kill the corner. Unfortunatly, I missed to fully evalute the ko threat which was way more severe than what my poor reading told me... and I finally lose that game.

A few more try for the fun

[Marcus]

@drmwc:

Yes, the ko result is interesting. I hadn't read that particular variation in my own reading, so thanks for pointing it out.

@oca:

That last attempt is a good start for reading, but perhaps you should increase the breadth of your reading from 2 candidate moves to 3. You covered two outside moves trying to reduce or gain eyespace (depending on who is playing the move), but perhaps either Black or White might want to play a critical inside move instead? Those variations (along with drmwc's variations due to the ladder) can also be interesting and instructive:

$$W This seems like an interesting point for either B or W
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X . |
$$ . . . O X X . |
$$ . . . O X . a |
$$ . . . 1 . 2 . |
$$ . . . . . . . |
$$ --------------+

Click Here To Show Diagram Code

[go]$$W This seems like an interesting point for either B or W
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X . |
$$ . . . O X X . |
$$ . . . O X . a |
$$ . . . 1 . 2 . |
$$ . . . . . . . |
$$ --------------+[/go]

And because this reading practice is good for me, too, here's another possibility (there may be death in the hane ...):

$$W Looks like an L group, doesn't it?
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X 1 |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . 3 2 4 . . |
$$ . . . 5 . . . |
$$ --------------+

Click Here To Show Diagram Code

[go]$$W Looks like an L group, doesn't it?
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X 1 |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . 3 2 4 . . |
$$ . . . 5 . . . |
$$ --------------+[/go]

Lots of possibilities.

[Uberdude]

$$W Looks like an L group, doesn't it?
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X 1 |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . 3 2 4 a . |
$$ . . . 5 . . . |
$$ --------------+

Click Here To Show Diagram Code

[go]$$W Looks like an L group, doesn't it?
$$ . . . . . . . |
$$ . . . . . . . |
$$ . . . . O . . |
$$ . . . . X O . |
$$ . . . O O X 1 |
$$ . . . O X X . |
$$ . . . O X . . |
$$ . . 3 2 4 a . |
$$ . . . 5 . . . |
$$ --------------+[/go]

4 at a is better for ko shape (white can also think about 3 at a to stop that).