Davies - Life or Death - Problem 9.4

[Shawn Ligocki]

I got a different solution to Problem 4 in Chapter 9 of Davies' "Life or Death" and I'm curious if my solution is wrong or less optimal in some way or just a different solution.

The problem is:

$$Bc Black to make a Ko
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . . O X .
$$ | . . O X .
$$ | . O X X .
$$ | . . . . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc Black to make a Ko
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . . O X .
$$ | . . O X .
$$ | . O X X .
$$ | . . . . .
$$ +-----------[/go]

My solution is:

$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | 5 4 O X .
$$ | . 3 O X .
$$ | 1 O X X .
$$ | . 2 . . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | 5 4 O X .
$$ | . 3 O X .
$$ | 1 O X X .
$$ | . 2 . . .
$$ +-----------[/go]

Davies lists the solution as:

$$Bc
$$ | . . . . .
$$ | 5 X X . .
$$ | O O X . .
$$ | . 6 O X .
$$ | 3 4 O X .
$$ | . 7 O X .
$$ | 1 O X X .
$$ | . 2 . . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . . . .
$$ | 5 X X . .
$$ | O O X . .
$$ | . 6 O X .
$$ | 3 4 O X .
$$ | . 7 O X .
$$ | 1 O X X .
$$ | . 2 . . .
$$ +-----------[/go]

Is it just that Davies solution closes off the outside in sente? So that even if Black loses the ko, White doesn't get any endgame pushes?

[Bill Spight]

Yes. Both solutions lead to ko with White taking first. In the standard solution the ko is less favorable for White.

[clemi]

And what about this for white, is it better for her ?

$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . . O X .
$$ | 2 . O X .
$$ | 1 O X X .
$$ | 4 3 . . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . . O X .
$$ | 2 . O X .
$$ | 1 O X X .
$$ | 4 3 . . .
$$ +-----------[/go]

[Bill Spight]

$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . 6 O X .
$$ | 2 . O X .
$$ | 1 O X X .
$$ | 4 3 5 . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | . 6 O X .
$$ | 2 . O X .
$$ | 1 O X X .
$$ | 4 3 5 . .
$$ +-----------[/go]

takes ko.

[Bill Spight]

Oops! This is better. In fact, in a real game it would probably be the main line.

$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | 3 4 O X .
$$ | 2 5 O X .
$$ | 1 O X X .
$$ | . . . . .
$$ +-----------

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . . . .
$$ | . X X . .
$$ | O O X . .
$$ | . . O X .
$$ | 3 4 O X .
$$ | 2 5 O X .
$$ | 1 O X X .
$$ | . . . . .
$$ +-----------[/go]

looks better than the book line because of the possible sente endgame on the left side.

[MagicMagor]

Edit: Forget what i wrote - i was wrong. (Doing tsumego before coffee is not a good idea)

[DrStraw]

Edit: Forget what i wrote - i was wrong. (Doing tsumego before coffee is not a good idea)

A bit tough to forget something which is not even available to see.

[Aidoneus]

Edit: Forget what i wrote - i was wrong. (Doing tsumego before coffee is not a good idea)

A bit tough to forget something which is not even available to see.

Don't think about a pink elephant!