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Corner Situation in Club Game
http://www.lifein19x19.com/viewtopic.php?f=15&t=9528
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Author:  moyoaji [ Wed Dec 11, 2013 11:48 pm ]
Post subject:  Corner Situation in Club Game

In a club game tonight I got into a situation where I tried to play a move in sente that would let my stones connect, but my opponent ignored and kept me cut. I had read that black could do no better than ko in the corner.

Click Here To Show Diagram Code
[go]$$Wm1 Anything but ko?
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | . X X O O . X .
$$ | . . . X O O X .
$$ | . 1 X . X O . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ -----------------[/go]


I was able to kill the corner, but my opponent felt he could've lived if he'd played better. Was I wrong? Does black have a way to live in the corner without an unfavorable ko? Or even is there a way for white to kill without the ko? Looking at varitions on my own I don't think a ko is avoidable.

Click Here To Show Diagram Code
[go]$$Wm1 This is the ko I foresaw...
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | . X X O O . X .
$$ | . 3 . X O O X .
$$ | . 1 X C X O . .
$$ | . 2 . 4 5 6 . .
$$ | . . . . . . . .
$$ -----------------[/go]


For those wondering how this developed. This was the general idea (I don't remember everything about the surrounding stones perfectly, but the corner situation is accurate.)
Click Here To Show Diagram Code
[go]$$Wm1 :b8: tenuki
$$ | . . 4 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . 1 3 . . . .
$$ | . . 2 . . . . .
$$ | . . . X 5 7 . .
$$ | . . . . 6 . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ -----------------[/go]


Click Here To Show Diagram Code
[go]$$Wm1 Later...
$$ | . 0 X X X O . .
$$ | 8 . . . . 3 . .
$$ | 7 4 X . X . . .
$$ | 9 5 O O . . . .
$$ | . 6 X 1 . . . .
$$ | . . . X O O . .
$$ | . . 2 . X . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ -----------------[/go]


Click Here To Show Diagram Code
[go]$$Wm1 And finally...
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | . X X O O . X .
$$ | . . . X O O 2 .
$$ | . 3 X . X 1 . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ -----------------[/go]

Author:  SmoothOper [ Thu Dec 12, 2013 8:19 am ]
Post subject:  Re: Corner Situation in Club Game

Is that a ko?

Click Here To Show Diagram Code
[go]$$Wm1 This is the ko I foresaw...
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | . X X O O . X .
$$ | b 3 . X O O X .
$$ | . 1 X 6 X O . .
$$ | . 2 . 4 5 a . .
$$ | . . . . . . . .
$$ -----------------[/go]


Click Here To Show Diagram Code
[go]$$Wm1 This is the ko I foresaw...
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | 9 X X O O . X .
$$ | 8 3 0 X O O X .
$$ | . 1 X 6 X O . .
$$ | . 2 . 4 5 7 . .
$$ | . . . . . . . .
$$ -----------------[/go]


Click Here To Show Diagram Code
[go]$$Wm1 This is the ko I foresaw...
$$ | X . . . . O O O
$$ | O X X . X . X .
$$ | O O O O . X . .
$$ | O X X O O . X .
$$ | 3 O X X O O X .
$$ | 1 O X X X X O . .
$$ | 2 X X . X O O . .
$$ | . . . 4 . . . .
$$ -----------------[/go]

Author:  moyoaji [ Thu Dec 12, 2013 9:34 am ]
Post subject:  Re: Corner Situation in Club Game

Uh... First, your last diagram is not of the same board position. Second, white can play like this:



Attachments:
StillKoForLife.sgf [206 Bytes]
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Author:  Bill Spight [ Thu Dec 12, 2013 9:59 am ]
Post subject:  Re: Corner Situation in Club Game



:)

:w11: is a mistake.

Author:  moyoaji [ Fri Dec 13, 2013 1:05 am ]
Post subject:  Re: Corner Situation in Club Game

Thanks Bill.

Yes, :w11: is clearly a mistake. Without that move black is just dead.

It does look like an interesting position can come out of this. By avoiding kos I think both sides could achieve life.


Author:  ez4u [ Fri Dec 13, 2013 7:04 am ]
Post subject:  Re: Corner Situation in Club Game

The White play at F1 is a waste of time if White is going to connect at F2. White plays the ko.

However, instead of D2, doesn't Black just play A4? How will White prevent Black from living?

Edit: Oops, wrong again. A4 looks like ko also after A5. :sad:

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