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Offline lightvector
 Post subject: Tesuji Problem
Post #1 Posted: Sun Sep 11, 2011 10:04 am 
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I have a question about a tsumego. In Davies' book "Tesuji", the following problem is given, with the following solution.
Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . 4 3 . . . . . . . . . .
$$ | . 5 O . 1 . . . . . . . .
$$ | . . . 2 O X X . . . . . .
$$ | . . X X X O . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


But what if white responds this way?

Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . . 3 . . . . . . . . . .
$$ | . . O . 1 . . . . . . . .
$$ | . . 4 2 O X X . . . . . .
$$ | . . X X X O . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


I'm having difficulty reading this out. Can black capture white from here? There are a lot of variations where white gets into a capturing race with the corner. And there's also the problem that unless black spends a whole move to defend D7, white can escape there if he ever has at least 3 liberties on his turn.

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Offline daal
 Post subject: Re: Tesuji Problem
Post #2 Posted: Sun Sep 11, 2011 11:01 am 
Oza
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lightvector wrote:

But what if white responds this way?

Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . . 3 . . . . . . . . . .
$$ | . . O . 1 . . . . . . . .
$$ | . . 4 2 O X X . . . . . .
$$ | . . X X X O . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


I'm having difficulty reading this out. Can black capture white from here? There are a lot of variations where white gets into a capturing race with the corner. And there's also the problem that unless black spends a whole move to defend D7, white can escape there if he ever has at least 3 liberties on his turn.


Seems to me that b1 catches black.


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


Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . 3 X 4 . . . . . . . . .
$$ | . 2 O 5 X . . . . . . . .
$$ | . 1 O O O X X . . . . . .
$$ | . . X X X O . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


or

Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 7 3 X . . . . . . . . . .
$$ | . 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . .
$$ | . 5 X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]

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Offline Joaz Banbeck
 Post subject: Re: Tesuji Problem
Post #3 Posted: Sun Sep 11, 2011 11:05 am 
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daal wrote:
...
Click Here To Show Diagram Code
[go]$$c
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 7 3 X . . . . . . . . . .
$$ | . 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . .
$$ | . 5 X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]




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

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Offline emeraldemon
 Post subject: Re: Tesuji Problem
Post #4 Posted: Sun Sep 11, 2011 11:15 am 
Gosei
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seems like :b7: has to be here:

Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . 3 X 7 . . . . . . . . .
$$ | . 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . . .
$$ | . 5 X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


looks like maybe a ko? I agree it seems very complicated.

Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | 8 2 . . O . . . . . . . .
$$ | 1 X X X . . . . . . . . .
$$ | . O O . X . . . . . . . .
$$ | O . O O O X X . . . . . .
$$ | 5 O X X X O . . . . . . .
$$ | 4 X X O O O . O . . . . .
$$ | 7 . X X O . . . . . . . .
$$ | . 6 . 3 9 . . . . . . . .
$$ --------------------------[/go]
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Offline Shaddy
 Post subject: Re: Tesuji Problem
Post #5 Posted: Sun Sep 11, 2011 11:39 am 
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Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 7 3 X . . . . . . . . . .
$$ | 5 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]

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Offline lightvector
 Post subject: Re: Tesuji Problem
Post #6 Posted: Sun Sep 11, 2011 12:51 pm 
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Shaddy wrote:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 7 3 X . . . . . . . . . .
$$ | 5 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


But it's still ko if white descends?

Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 8 X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 6 4 X O O O . O . . . . .
$$ | 9 . X X O . . . . . . . .
$$ | . . . 7 . . . . . . . . .
$$ --------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . 9 . O . . . . . . . .
$$ | 6 X X 7 8 . . . . . . . .
$$ | 1 O O 2 X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | . 4 X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]
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Offline Solomon
 Post subject: Re: Tesuji Problem
Post #7 Posted: Sun Sep 11, 2011 1:19 pm 
Gosei
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lightvector wrote:
Shaddy wrote:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 7 3 X . . . . . . . . . .
$$ | 5 2 O . X . . . . . . . .
$$ | 6 1 O O O X X . . . . . .
$$ | . 4 X X X O . . . . . . .
$$ | . . X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


But it's still ko if white descends?

Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | 8 X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 6 4 X O O O . O . . . . .
$$ | 9 . X X O . . . . . . . .
$$ | . . . 7 . . . . . . . . .
$$ --------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . 9 . O . . . . . . . .
$$ | 6 X X 7 8 . . . . . . . .
$$ | 1 O O 2 X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | . 4 X O O O . O . . . . .
$$ | . . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]
Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 4 . X O O O . O . . . . .
$$ | 6 . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]

Click Here To Show Diagram Code
[go]$$Wcm1 10 at 5
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 7 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 4 9 X O O O . O . . . . .
$$ | 5 6 X X O . . . . . . . .
$$ | 8 . . . . . . . . . . . .
$$ --------------------------[/go]

Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 7 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 4 5 X O O O . O . . . . .
$$ | 8 6 X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]

This post by Solomon was liked by 3 people: cyclops, ez4u, lightvector
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Offline lightvector
 Post subject: Re: Tesuji Problem
Post #8 Posted: Sun Sep 11, 2011 2:07 pm 
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Araban wrote:
Click Here To Show Diagram Code
[go]$$Wcm1
$$ | . . . . . . . . . . . . .
$$ | . . O O X O . . . . . . .
$$ | . . . . O . . . . . . . .
$$ | . X X 2 . . . . . . . . .
$$ | 1 O O . X . . . . . . . .
$$ | 5 X O O O X X . . . . . .
$$ | . 3 X X X O . . . . . . .
$$ | 4 . X O O O . O . . . . .
$$ | 6 . X X O . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ --------------------------[/go]


Wow B6 is really neat. Thanks. :salute:

I wonder why the book author didn't choose a simpler position to illustrate this tesuji. Or maybe this line of resistance was just overlooked.

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Offline cyclops
 Post subject: Re: Tesuji Problem
Post #9 Posted: Mon Sep 12, 2011 5:44 am 
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Click Here To Show Diagram Code
[go]$$Wc
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . O O X O . . .
$$ | . . . . O . . . .
$$ | . X X X . . . . .
$$ | O O O . X . . . .
$$ | O . O O O X X . .
$$ | . O X X X O . . .
$$ | X 2 X O O O . O .
$$ | X 1 X X O . . . .
$$ | . 3 . . . . . . .
$$ +-------------------[/go]


where is the unconditional kill?
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Offline daal
 Post subject: Re: Tesuji Problem
Post #10 Posted: Mon Sep 12, 2011 7:08 am 
Oza
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cyclops wrote:
Click Here To Show Diagram Code
[go]$$Wc
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . O O X O . . .
$$ | . . . . O . . . .
$$ | . X X X . . . . .
$$ | O O O . X . . . .
$$ | O . O O O X X . .
$$ | . O X X X O . . .
$$ | X 2 X O O O . O .
$$ | X 1 X X O . . . .
$$ | . 3 . . . . . . .
$$ +-------------------[/go]


where is the unconditional kill?


How about this? White can play at neither a nor b, but black can play at a anytime.
Click Here To Show Diagram Code
[go]$$
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . O O X O . . .
$$ | . . . . O . . . .
$$ | 5 X X X . . . . .
$$ | O O O 3 X . . . .
$$ | O . O O O X X . .
$$ | b O X X X O . . .
$$ | X X X O O O . O .
$$ | X O X X O . . . .
$$ | a O 4 1 2 . . . .
$$ +-------------------[/go]

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Offline cyclops
 Post subject: Re: Tesuji Problem
Post #11 Posted: Mon Sep 12, 2011 7:52 am 
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daal wrote:
How about this?


thx, Daal. Great!
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