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Offline walleye
 Post subject: Tsumego from a game
Post #1 Posted: Thu Dec 23, 2010 8:20 pm 
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Tsumego from a game. What's the status of black group in the upper left corner?

Click Here To Show Diagram Code
[go]$$c This is a label for the diagram.
$$ -------------------------------
$$ | . X O . . X . . . . . . . .
$$ | X O O X X X O O O O . . . .
$$ | . X . X O O X X X X O O . .
$$ | O X X X O O O X . X O . O .
$$ | . O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]
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Offline Shaddy
 Post subject: Re: Tsumego from a game
Post #2 Posted: Thu Dec 23, 2010 9:09 pm 
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B to play- alive, W to play- looks like 10k year ko.
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Offline walleye
 Post subject: Re: Tsumego from a game
Post #3 Posted: Fri Dec 24, 2010 7:21 pm 
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Shaddy wrote:
B to play- alive, W to play- looks like 10k year ko.

I would appreciate a diagram. I don't see a 10k year ko.
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Offline ethanb
 Post subject: Re: Tsumego from a game
Post #4 Posted: Fri Dec 24, 2010 7:50 pm 
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B first = alive
W first = alive in seki

Click Here To Show Diagram Code
[go]$$Wc This is also a diagram label.
$$ -------------------------------
$$ | 4 X O 1 . X 5 . . . . . . .
$$ | X O O X X X O O O O . . . .
$$ | 2 X . X O O X X X X O O . .
$$ | O X X X O O O X . X O . O .
$$ | 3 O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]


There's also a more complicated variation where white captures inside and black takes outside, but it doesn't really do anything interesting - still seki unless I miss something.
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Offline Shaddy
 Post subject: Re: Tsumego from a game
Post #5 Posted: Fri Dec 24, 2010 10:48 pm 
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hmm, ethan is right.
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Offline walleye
 Post subject: Re: Tsumego from a game
Post #6 Posted: Sun Dec 26, 2010 4:56 pm 
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This is a more interesting variation in my opinion.

Click Here To Show Diagram Code
[go]$$Wc This is a label for the diagram.
$$ -------------------------------
$$ | 1 . O 3 . X . . . . . . . .
$$ | X O O X X X O O O O . . . .
$$ | 2 X . X O O X X X X O O . .
$$ | O X X X O O O X . X O . O .
$$ | . O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]
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Offline ethanb
 Post subject: Re: Tsumego from a game
Post #7 Posted: Sun Dec 26, 2010 11:39 pm 
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walleye wrote:
This is a more interesting variation in my opinion.

Click Here To Show Diagram Code
[go]$$Wc This is a label for the diagram.
$$ -------------------------------
$$ | 1 . O 3 . X . . . . . . . .
$$ | X O O X X X O O O O . . . .
$$ | 2 X . X O O X X X X O O . .
$$ | O X X X O O O X . X O . O .
$$ | . O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]



If the seki isn't enough for white to win, maybe he can hope that black makes a mistake and starts a ko. But white loses about 1.5 points (on the outside) by making this seki instead of the other one. Amusing stuff happens if black captures six stones inside though (it's still a ko.)
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Offline walleye
 Post subject: Re: Tsumego from a game
Post #8 Posted: Mon Dec 27, 2010 12:48 am 
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ethanb wrote:

Amusing stuff happens if black captures six stones inside though (it's still a ko.)


What ko? If white doesn't make a seki, Black can live by capturing. There is no ko there as far as I can see.
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Offline ethanb
 Post subject: Re: Tsumego from a game
Post #9 Posted: Mon Dec 27, 2010 1:07 am 
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walleye wrote:
ethanb wrote:

Amusing stuff happens if black captures six stones inside though (it's still a ko.)


What ko? If white doesn't make a seki, Black can live by capturing. There is no ko there as far as I can see.


Ack, you're right - it's past my bedtime. :) I forgot about number 5 in the next diagram when I was reading ahead.

Click Here To Show Diagram Code
[go]$$Bc Yet another diagram label.
$$ -------------------------------
$$ | O 2 O O 3 X 4 . . . . . . .
$$ | X O O X X X O O O O . . . .
$$ | X X 5 X O O X X X X O O . .
$$ | O X X X O O O X . X O . O .
$$ | 1 O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]


Click Here To Show Diagram Code
[go]$$Bc White fails to make a ko.
$$ -------------------------------
$$ | . 6 7 . X X O . . . . . . .
$$ | X . W X X X O O O O . . . .
$$ | X X X X O O X X X X O O . .
$$ | . X X X O O O X . X O . O .
$$ | X O O O . O X . X O O O . .
$$ | . O . . O O X X X O . . . .
$$ | . O O O . O O . . . . . . .
$$ | . X X O X X O . . . . . . .
$$ | . X O X . . X X . . . . . .
$$ | . . . X X X . . . , . . . .
$$ | . . . X . . . . . . . . . .
$$ | . . . . . . . . . . . . . .[/go]


So yeah, just a seki, but 1.5 points worse than the other one.

Actually, even if the spot below the marked stone was miraculously open, black could just connect to the right of 7 and it would still be seki.
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Offline Bill Spight
 Post subject: Re: Tsumego from a game
Post #10 Posted: Tue Dec 28, 2010 7:58 am 
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There is one point that has not been mentioned. :)


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Last edited by Bill Spight on Thu Aug 01, 2019 9:23 am, edited 1 time in total.
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Offline Magicwand
 Post subject: Re: Tsumego from a game
Post #11 Posted: Tue Dec 28, 2010 8:50 am 
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if double ko then black is alive but this does not necessary guarantee win.
if white can create a double ko somewhere else then black can make no decision.
having infinite ko is pretty strong advantage that can create havoc somewhere else.
so answer is not so clear cut.

all depends on the situation is the correct answer.

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