Life In 19x19

I'm sure you strong players are able to read things out much better than somebody like I can, so here are two examples where I've tried playing variations out on the board, and am still not quite certain of the correct answers.

1. Black is trying to attack the White group at top. If Black plays 1 at S12, can White save the group?

Click Here To Show Diagram Code

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

2. In this game I had White, and after trying to read the position out, I felt that if I played White 1, I'd be able to connect it to one or another of my groups, which would result in the Black group at top not able to get a second eye.

Click Here To Show Diagram Code

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

In the game, the Black group did in fact die, although after the game we went through the position and with our SDK knowledge figured that Black can probably save the group, but White can connect. Can Black save the group? If so, how far should White keep playing before letting Black save it and looking for a bigger sente move someplace else?

Don't have a serious answer to anything yet, but I wanted to note that during your game you accidentally recreated (more or less) a famous tsumego... I think it's from Gokyo Shumyo

The Shining Pearl Seeks the Ocean wrote:

$$Wc White to play.
$$ . . . . . .
$$ , X . X . .
$$ . . W . . .
$$ . X . . X .
$$ . . . X . .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$Wc White to play.
$$ . . . . . .
$$ , X . X . .
$$ . . W . . .
$$ . X . . X .
$$ . . . X . .
$$ . . . . . .[/go]

Fedya wrote:
2. In this game I had White, and after trying to read the position out, I felt that if I played White 1, I'd be able to connect it to one or another of my groups, which would result in the Black group at top not able to get a second eye.

$$Wc
$$ +-------------------------------------+
$$ |. . . . . X . . . . . . . . . . . . .|
$$ |X . O . X O O . X . O X . X O . . . .|
$$ |. . O X O X O . O O O X . X O O X . .|
$$ |. O O O O X . O . X O X X X X O O O .|
$$ |O O X . X X . . . X O X O . O . . O .|
$$ |O X X . . . X O O X O X O O O O . O .|
$$ |X . . . . . X X O X X X X X O . . O .|
$$ |. X . . . . . . O . X . X O . . O X .|
$$ |. . . . . X O . . O O X O O O O O O .|
$$ |. . X , . X O . O , X . X . . , . . O|
$$ |. . . . . . X O . . . 1 . . O . X O .|
$$ |. X . . . . X . O . X . . X O . . X O|
$$ |X . . . . . . . . . . . X . . X . X .|
$$ |O X X . . . . X . . . . . O O X X . .|
$$ |O O X . . . . . . O . O . . . O O X .|
$$ |. O O X . . . . X , . . O . O , X . .|
$$ |. . O X . . X . . . X X X O . O O X .|
$$ |. O . O X . . . . . . . . X O . . X .|
$$ |. . . O X . . . . . . . . . . . . . .|
$$ +-------------------------------------+

Click Here To Show Diagram Code

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

In the game, the Black group did in fact die, although after the game we went through the position and with our SDK knowledge figured that Black can probably save the group, but White can connect. Can Black save the group? If so, how far should White keep playing before letting Black save it and looking for a bigger sente move someplace else?

I watched this game live and was rooting for you the whole time. I was very impressed that despite being far behind, you kept your composure and found this move. I am fairly certain that the sequence your opponent showed after the game was faulty, and that black will die a certain death - but if a stronger player can tesuji his way out, I'd like to see it too.

1. I don't think White can live.

2. My initial impression is that Black can live:

Click Here To Show Diagram Code

[go]$$Wc
$$ +-------------------------------------+
$$ |. . . . . X . . . . . . . . . . . . .|
$$ |X . O . X O O . X . O X . X O . . . .|
$$ |. . O X O X O . O O O X . X O O X . .|
$$ |. O O O O X . O . X O X X X X O O O .|
$$ |O O X . X X . . . X O X O . O . . O .|
$$ |O X X . . . X O O X O X O O O O . O .|
$$ |X . . . . . X X O X X X X X O . . O .|
$$ |. X . . . . . . O . X . X O . . O X .|
$$ |. . . . . X O . . O O X O O O O O O .|
$$ |. . X , . X O . O 9 X 2 X . . , . . O|
$$ |. . . . . . X O . 6 5 1 . . O . X O .|
$$ |. X . . . . X . O 7 X 3 . X O . . X O|
$$ |X . . . . . . . . . 8 4 X . . X . X .|
$$ |O X X . . . . X . 0 . . . O O X X . .|
$$ |O O X . . . . . . O . O . . . O O X .|
$$ |. O O X . . . . X , . . O . O , X . .|
$$ |. . O X . . X . . . X X X O . O O X .|
$$ |. O . O X . . . . . . . . X O . . X .|
$$ |. . . O X . . . . . . . . . . . . . .|
$$ +-------------------------------------+[/go]

Araban wrote:2. My initial impression is that Black can live:

I stand corrected. Thanks. Nonetheless I stick with my kudos.

1. I had Black in the game, and afterwards had a feeling I'd screwed up: I didn't play S12, but S15.

2. Ahh, but Araban, would you have been able to find that sequence with the clock running and without placing any stones? I think that's more or less the sequence (or one of them) my opponent looked at after the game, and one that I looked at as well when I was trying to analyze the game. One of the problems I have with reading during the game is a distressing tendency not to notice until after the stones are actually on the board that a stone or group is in atari, putting all my well-laid plans into chaos.

For the record, I tried a different White 3 in the actual game:

Click Here To Show Diagram Code

[go]$$Wc
$$ +-------------------------------------+
$$ |. . . . . X . . . . . . . . . . . . .|
$$ |X . O . X O O . X . O X . X O . . . .|
$$ |. . O X O X O . O O O X . X O O X . .|
$$ |. O O O O X . O . X O X X X X O O O .|
$$ |O O X . X X . . . X O X O . O . . O .|
$$ |O X X . . . X O O X O X O O O O . O .|
$$ |X . . . . . X X O X X X X X O . . O .|
$$ |. X . . . . . . O . X . X O . . O X .|
$$ |. . . . . X O . . O O X O O O O O O .|
$$ |. . X , . X O . O 0 X 2 X . . , . . O|
$$ |. . . . . . X O . 4 3 1 . . O . X O .|
$$ |. X . . . . X . O . X 5 . X O . . X O|
$$ |X . . . . . . . . . 6 7 X . . X . X .|
$$ |O X X . . . . X . . 9 8 . O O X X . .|
$$ |O O X . . . . . . O . O . . . O O X .|
$$ |. O O X . . . . X , . . O . O , X . .|
$$ |. . O X . . X . . . X X X O . O O X .|
$$ |. O . O X . . . . . . . . X O . . X .|
$$ |. . . O X . . . . . . . . . . . . . .|
$$ +-------------------------------------+[/go]

Click Here To Show Diagram Code

[go]$$Wcm11 And now Black will die
$$ +-------------------------------------+
$$ |. . . . . X . . . . . . . . . . . . .|
$$ |X . O . X O O . X . O X . X O . . . .|
$$ |. . O X O X O . O O O X . X O O X . .|
$$ |. O O O O X . O . X O X X X X O O O .|
$$ |O O X . X X . . . X O X O . O . . O .|
$$ |O X X . . . X O O X O X O O O O . O .|
$$ |X . . . . . X X O X X X X X O . . O .|
$$ |. X . . . . . . O . X . X O . . O X .|
$$ |. . . . . X O . . O O X O O O O O O .|
$$ |. . X , . X O . O X X X X . . , . . O|
$$ |. . . . . . X O . X O O . . O . X O .|
$$ |. X . . . . X . O 3 X O . X O . . X O|
$$ |X . . . . . . . 2 . X O X . . X . X .|
$$ |O X X . . . . X . . O X 1 O O X X . .|
$$ |O O X . . . . . . O . O . . . O O X .|
$$ |. O O X . . . . X , . . O . O , X . .|
$$ |. . O X . . X . . . X X X O . O O X .|
$$ |. O . O X . . . . . . . . X O . . X .|
$$ |. . . O X . . . . . . . . . . . . . .|
$$ +-------------------------------------+[/go]

Fedya wrote:2. Ahh, but Araban, would you have been able to find that sequence with the clock running and without placing any stones?

That is the sequence I saw as soon as I looked at the diagream. It took all of two seconds, at most. I see it as almost a one way street. I took another few seconds to check other variations but if it were a real game and I were under time pressure I would probably just go with the first thing I saw.

Fedya wrote:2. Ahh, but Araban, would you have been able to find that sequence with the clock running and without placing any stones?

Yes.

{curses the strong players}