Life In 19x19

I'm wondering how you would respond to the marked stone played below. I'm asking because this move wasn't listed under the solutions and I wonder if I'm missing something because this seems to work too and was the intuitive response for me.

Click Here To Show Diagram Code

[go]$$W
$$
$$ - . . . . . . . . .
$$ - . X X , . . . . .
$$ - . O O X X . X . .
$$ - . . . O O X . . .
$$ - . @ . . . . . . .
$$ --------------------[/go]

Kirby, the same aji exists in Solomon's variation of placement first, as white can also block the hane if it is played as move 3, black cuts, white captures, black plays 2-2 and then the same outside aji, but with white losing 3 rather than 2 stones on the left edge. FWIW placement first was my instinct too in this problem, probably because in related shapes such as killing the L shape when they attempt to live with that 2-1, you do need to do the placement before the hane, or else they play the 1-2 and live, but here the hane threatens to capture 2 stones not just reduce eyespace so either order works.

Uberdude wrote:Kirby, the same aji exists in Solomon's variation of placement first, as white can also block the hane if it is played as move 3, black cuts, white captures, black plays 2-2 and then the same outside aji, but with white losing 3 rather than 2 stones on the left edge. FWIW placement first was my instinct too in this problem, probably because in related shapes such as killing the L shape when they attempt to live with that 2-1, you do need to do the placement before the hane, or else they play the 1-2 and live, but here the hane threatens to capture 2 stones not just reduce eyespace so either order works.

Good point. I didn't think enough about the aji in Solomon's variation.

I was trying to find a reason that hane was worse in this case, but maybe it's actually not.

On this one, I wonder if black can make good use of the marked stones. What do you think?

Click Here To Show Diagram Code

[go]$$W Black to Move
$$ - . . . . . . . . . . . . . . .
$$ - . . . . . . . . . . . . . . .
$$ - X . . . . . O . . O . . . .
$$ - O X X X . . O X X O . . . .
$$ - O O O , O . . O O , X X . . .
$$ - . . O . . X . X X O . O X X .
$$ - B . B O . . . . O O . O . . .
$$ - . B . O . . . . . . . . . . .
$$ --------------------[/go]

No takers, huh? I believe the marked stones are alive.

gamesorry wrote:

I think 4-3 should be the first move. If white replies with 4-4:

$$B Black to Move
$$ - . . . . . . . . . . . . . . .
$$ - . . . . . . . . . . . . . . .
$$ - X . . . . . O . . O . . . .
$$ - O X X X . . O X X O . . . .
$$ - O O O 2 O . . O O , X X . . .
$$ - . . O 1 3 X . X X O . O X X .
$$ - B . B O 6 7 . . O O . O . . .
$$ - . B 9 O 5 4 8 . . . . . . . .
$$ --------------------

Click Here To Show Diagram Code

[go]$$B Black to Move
$$ - . . . . . . . . . . . . . . .
$$ - . . . . . . . . . . . . . . .
$$ - X . . . . . O . . O . . . .
$$ - O X X X . . O X X O . . . .
$$ - O O O 2 O . . O O , X X . . .
$$ - . . O 1 3 X . X X O . O X X .
$$ - B . B O 6 7 . . O O . O . . .
$$ - . B 9 O 5 4 8 . . . . . . . .
$$ --------------------[/go]

There is an essential move that must be made previously.

Why? Gamesorrys sequence seems to work for Black.Could White improve somewhere?

Black 9 does not create a living shape. You must create an atari somehow in order to force the eye shape.

Joelnelsonb wrote:Black 9 does not create a living shape. You must create an atari somehow in order to force the eye shape.

Sure it does. There is one eye in the corner and one after black capture the three white stones in the 6 group. They can't escape. If white connects with 10 black plays on the first line and captures the whole group.

Joelnelsonb wrote:There is an essential move that must be made previously.

Joelnelsonb wrote:Black 9 does not create a living shape. You must create an atari somehow in order to force the eye shape.

It seems that after Black 9 white can't kill?