Life In 19x19

I was reading the page 48 chapter 5 in Basics of Go strategy titled Light Stones and Sabaki and was wondering about a sequence.



Here is the current situation.

Click Here To Show Diagram Code

[go]$$B "Black has mapped out a huge territorial framework in the upper right quadrant. The two Standard ways for white to reduce it are to cap at A or to attach at B. Let's look at the the cap." Source: The Basics of Go Strategy
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . X . . . . . , X b . |
$$ | . . O . . . . . . . . . . . a . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The sequence:

Click Here To Show Diagram Code

[go]$$W Black 2 at A also possible. "If Black wants to emphasize the top, he will play at A".
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . 10 . . . . |
$$ | . . . . . . . . . . . . 9 4 5 6 . . . |
$$ | . . . O . . . . . . . . . 3 X 8 . . . |
$$ | . . . , . . . . . X . . . a 7 , X . . |
$$ | . . O . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Wm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . O X . X . . . |
$$ | . . . O . . . . . . . . . O X X . . . |
$$ | . . . , . . . . . X . . . . O , X . . |
$$ | . . O . . . . . . . . 1 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

My Question: What happens if Black captures at 8 rather than connecting at A?

Click Here To Show Diagram Code

[go]$$W What happens if Black captures at 8 rather than connecting at A?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . 4 5 6 . . . |
$$ | . . . O . . . . . . . . . 3 X a . . . |
$$ | . . . , . . . . . X . . . . 7 , X . . |
$$ | . . O . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Continuation attempt:

Click Here To Show Diagram Code

[go]$$B Move 8 now numbered as 1. Is white satisfied with this or is there a different variation?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . 4 X . X . . . |
$$ | . . . O . . . . . . . . . O X 2 3 . . |
$$ | . . . , . . . . . X . . . . O 5 X . . |
$$ | . . O . . . . . . . . 6 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Note: This is my first time creating diagrams, and I wish I had just embedded an sgf file

Continuation attempt:

$$B Move 8 now numbered as 1. Is white satisfied with this or is there a different variation?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . 4 X . X . . . |
$$ | . . . O . . . . . . . . . O X 2 3 . . |
$$ | . . . , . . . . . X . . . . O 5 X . . |
$$ | . . O . . . . . . . . 6 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$B Move 8 now numbered as 1. Is white satisfied with this or is there a different variation?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . 4 X . X . . . |
$$ | . . . O . . . . . . . . . O X 2 3 . . |
$$ | . . . , . . . . . X . . . . O 5 X . . |
$$ | . . O . . . . . . . . 6 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

3 must connect for black, he can't fight the ko. Then w can probably make something happen there

dtslife wrote:

$$W What happens if Black captures at 8 rather than connecting at A?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . 4 5 6 . . . |
$$ | . . . O . . . . . . . . . 3 X a . . . |
$$ | . . . , . . . . . X . . . . 7 , X . . |
$$ | . . O . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$W What happens if Black captures at 8 rather than connecting at A?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . 4 5 6 . . . |
$$ | . . . O . . . . . . . . . 3 X a . . . |
$$ | . . . , . . . . . X . . . . 7 , X . . |
$$ | . . O . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

If Black captures with B8 then W should usually play atari at a. This is a forcing move and usuall Black must connect because the ko is too big for Black to fight. Here is the expected sequence in this situation:

Click Here To Show Diagram Code

[go]$$W What happens if Black captures at 8 rather than connecting at A?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . X 2 X . . . |
$$ | . . . O . . . . . . . . 3 O X 1 . . . |
$$ | . . . , . . . . . X . . . . O 4 X . . |
$$ | . . O . . . . . . . . . 5 . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Now White has a good shape and has accomplished his goal of reducing the Black framework.

Thanks gowan and shaddy for the advice. I'm not sure if I'm seeing the same ko.

Follow up question:

Click Here To Show Diagram Code

[go]$$W What is the due punishment if black plays 2 rather than connecting at A? Where is the ko?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . X a X . . . |
$$ | . . . O . . . . . . . . . O X 1 2 . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

My attempt:

Click Here To Show Diagram Code

[go]$$W I feel like 5 is neccessary to separate the two groups. A is too passive and b feels too far.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . 4 X 3 X . . . |
$$ | . . . O . . . . . . b 5 a O a 1 2 . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

My attempt:

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . 6 4 X X O X . . . |
$$ | . . . O . . . . . 7 5 1 2 O a O X . . |
$$ | . . . , . . . . . X . . 3 . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

White five, in this diagram, might appear weak but perhaps white can start a ko.

Click Here To Show Diagram Code

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

I only see ko threats for white at A and at other points at that region.

dtslife wrote:Thanks gowan and shaddy for the advice. I'm not sure if I'm seeing the same ko.

$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . 6 4 . X X O X 9 . . |
$$ | . . . O . . . . 8 7 5 1 2 O a O X . . |
$$ | . . . , . . . . . X . . 3 . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

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

I only see ko threats for white at A and at other points at that region.

I think you're making it harder than it is... If black extends, white should atari immediately.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . 1 X O X 2 . . |
$$ | . . . O . . . . . . . . . O . O X . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Black takes the ko, white plays at A. White has yet another ko threat there after black blocks, while black has one ko threat at most in the upper left. If black tries to resist by connecting, he only makes it harder on himself:

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . 5 4 X 3 6 . . |
$$ | . . . . . . . . . . . . 1 X O X 2 . . |
$$ | . . . O . . . . . . . 8 . O . O X . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

(7 connects)

Will black try to connect to the 4th line stone? Sorry, can't do it. Black will still have to come back and capture two stones, and this way gives white wonderful thickness while damaging black's outside stone.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . 5 3 X X X X O . . |
$$ | . . . . . . . . . . 1 2 X X O X O . . |
$$ | . . . O . . . . . . 6 O 4 O . O X . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

thanks for the clarification ethanb

ethanb wrote:Black takes the ko, white plays at A. White has yet another ko threat there after black blocks, while black has one ko threat at most in the upper left. If black tries to resist by connecting, he only makes it harder on himself:

$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . 5 4 X 3 6 . . |
$$ | . . . . . . . . . . . . 1 X O X 2 . . |
$$ | . . . O . . . . . . . 8 . O . O X . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . 5 4 X 3 6 . . |
$$ | . . . . . . . . . . . . 1 X O X 2 . . |
$$ | . . . O . . . . . . . 8 . O . O X . . |
$$ | . . . , . . . . . X . . . . O . X . . |
$$ | . . O . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X a X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

(7 connects)

...

Isn't every single black move in that sequence an internal ko threat? That is, black can recapture the ko in between every move of that sequence. It seems awfully hard for white to win that ko...

I love this discussion. It adresses the kind of questions I ask myself but fail to answer because they are too difficult for me. What will the dans answer at Flovermind's clever question?

cyclops wrote:I love this discussion. It adresses the kind of questions I ask myself but fail to answer because they are too difficult for me. What will the dans answer at Flovermind's clever question?

too tell you the truth..i do not read that varation too deep unless i am forced to.
if my opponent plays such move then i will read and find the answer.
although i do not know the sequence but i know the answer good or bad.
if i had to read i will and find correct sequence because i know the answer. (lazy magicwand)

am i the only one who does this?

flOvermind wrote:

ethanb wrote:Black takes the ko, white plays at A. White has yet another ko threat there after black blocks, while black has one ko threat at most in the upper left. If black tries to resist by connecting, he only makes it harder on himself:


(7 connects)

...

Isn't every single black move in that sequence an internal ko threat? That is, black can recapture the ko in between every move of that sequence. It seems awfully hard for white to win that ko...

I haven't really been following the thread, so I don't know if the ko is best, but looking at this situation alone...

It isn't obvious to me that white doesn't have enough ko threats. He doesn't need to actually capture anything, pushing black along the second line or sealing him is more than enough - black's 8 stones on the first and second lines are hard to claim are efficiently placed

I think white has 3 good ko threats in the bottom right. As such...

[sgf-full](;GM[1]FF[4]AP[qGo:1.5.4]ST[1]
SZ[19]HA[0]KM[0]PW[White]PB[Black]DT[2011-01-18]PC[http://lifein19x19.com/]
AB[jd][nb][nq][oa][pb][pf][pq][qc][qd][qj][qn][qq][rp][rq]AW[ce][cq][dc][nc][ob][od][oe][op][pc][pn][pp][qo][qp][ro]LB[oq:a]PL[B]C[Diagram from http://lifein19x19.com/

]
;B[mb]C[B1]MN[1]
;W[qb]MN[2]
(
;B[pa]C[B3]MN[3]
;W[na]C[W4]MN[4]
;B[ma]C[B5]MN[5]
;W[qa]C[W6]MN[6]
;W[lc]C[W8]MN[8]
;LB[oq:a]
)
(
;B[oc];W[oq];B[or];W[ob];B[pa];W[na];B[oc];W[nr];B[mr];W[ob]
;B[ma];W[qa];B[oc];W[pr];B[ns];W[ob];B[na];W[lc]
(
;B[mc];W[md];B[ld];W[lb];B[oc];W[kd];B[nd];W[le]
)
(
;B[kb];W[lb];B[la];W[kc]
(
;B[jc];W[mc];B[oc];W[jb];B[pd];W[ka]
)
(
;B[jb];W[jc];B[ic];W[ka];B[ja];W[mc];B[oc];W[id]
)
)
(
;B[oc]
(
;W[kb]
)
(
;W[mc]
)
)
)
)[/sgf-full]

(My variations are added to the game tree, not the main variation)

I think it is hard for black to get a good result. He can answer in the bottom right differently, but I think white will get good compensation if black ignores a ko threat or answers differently. So white seems to have enough threats on the top.

amnal wrote:(My variations are added to the game tree, not the main variation)

I think it is hard for black to get a good result.

I understand that you consider W to be better off in all your variations ( including his loss in the bottom right corner ) than in the main variation below. I guess I can grasp that.

Click Here To Show Diagram Code

[go]$$Wm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . O X . X . . . |
$$ | . . . O . . . . . . . . . O X X . . . |
$$ | . . . , . . . . . X . . . . O , X . . |
$$ | . . O . . . . . . . . 1 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

cyclops wrote:

amnal wrote:(My variations are added to the game tree, not the main variation)

I think it is hard for black to get a good result.

I understand that you consider W to be better off in all your variations ( including his loss in the bottom right corner ) than in the main variation below. I guess I can grasp that.

$$Wm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . O X . X . . . |
$$ | . . . O . . . . . . . . . O X X . . . |
$$ | . . . , . . . . . X . . . . O , X . . |
$$ | . . O . . . . . . . . 1 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Wm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . O X . X . . . |
$$ | . . . O . . . . . . . . . O X X . . . |
$$ | . . . , . . . . . X . . . . O , X . . |
$$ | . . O . . . . . . . . 1 . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I don't know if white is inevitably better off, but I couldn't find anything to make me feel terrible if I was white.

I also said that I didn't know if the ko was best. But I would probably play it on general principle if it came up in a game, it is hard to win but also hard to lose.

Magicwand wrote:

cyclops wrote:I love this discussion. It adresses the kind of questions I ask myself but fail to answer because they are too difficult for me. What will the dans answer at Flovermind's clever question?

too tell you the truth..i do not read that varation too deep unless i am forced to.
if my opponent plays such move then i will read and find the answer.
although i do not know the sequence but i know the answer good or bad.
if i had to read i will and find correct sequence because i know the answer. (lazy magicwand)

am i the only one who does this?

I tend to do the same; I play mostly on instinct a lot of the time, unless my opponent's shape strikes me as funny or something. Then I stop and read...

Click Here To Show Diagram Code

[go]$$Wm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . X X . . . |
$$ | . . . . . . . . . . . . X X O X O . . |
$$ | . . . O . . . b . . . 1 . O 2 O X . . |
$$ | . . . , . . . b . B . . . . O , X . . |
$$ | . . O . . . . . . . . e . . O . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . c . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . d . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . O O O X . |
$$ | . . O . . . . . . . . . . X O X X X . |
$$ | . . . . . . . . . . . . . a X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Why not just play at ? After this, sabaki has already been achieved. Black's mark stone has been cut off from black's moyo by this point. As white, I would not continue the ko if it meant playing ugly bad moves such as 'a'. Instead, remember that if black wants to remove the ko aji along the bottom, he'll have to give you two free moves. With those, you can launch your own plans. If black doesn't solve the ko problem, you have a ton of aji for later.

After , if black plays , I would think about playing 'b' to pincer black's lonely stone. With that attack, combined with the threat to connect under, I think white's sabaki has been a success. Other large moves are 'c' and 'd', though I'm not sure if they're as good. White can also just make shape with his stones in the top right. 'e' is an example, though I'm not sure if it's the strongest local move.

With so many options, I think white has probably ended up better in this situation than in the game. That's my opinion anyway.