Problem from One of my KGS Games

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Charlie
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Problem from One of my KGS Games

Post by Charlie »

Here's a problem from my lunch-time game on KGS. White has just played :w1:, how should black kill? (Is it even possible to kill?)

Click Here To Show Diagram Code
[go]$$Wc Black to Respond
$$ | O X X X O . X . O O O X . X X X O . . |
$$ | X . X . X X X O O X X X O O X O . . . |
$$ | . . . X . . . X O O . X X O O . O . . |
$$ | . . . . . . . . X X . X O O O O . . . |
$$ | . . . X . . . X . , X . X X O X O O . |
$$ | . . . X . . . . X X O O X X X X X O . |
$$ | . . . . . . . X O O . . O 1 . . . X O |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ +---------------------------------------+[/go]


In the game, I managed to kill white's invasion. When I went over the game, afterwards, I realised that I should have stopped it entirely, several moves earlier. I also realised that white could have lived and possibly cut off my lower-right group. In fact, I couldn't find a move for black that would prevent white from doing so.
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mw42
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Re: Problem from One of my KGS Games

Post by mw42 »

Black's descent should kill. Think about the variations, then peak at the next hide box.
Click Here To Show Diagram Code
[go]$$Wc
$$ | O X X X O . X . O O O X . X X X O . . |
$$ | X . X . X X X O O X X X O O X O . . . |
$$ | . . . X . . . X O O . X X O O . O . . |
$$ | . . . . . . . . X X . X O O O O . . . |
$$ | . . . X . . . X . , X . X X O X O O . |
$$ | . . . X . . . . X X O O X X X X X O . |
$$ | . . . . . . . X O O . . O 1 2 . . X O |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ +---------------------------------------+[/go]


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


EDIT: Also, have a look at this tsumego: http://eidogo.com/?game=1Lc8jeHa#1Lc8jeHa. The situation is similar, but black can live.
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Lamp
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Re: Problem from One of my KGS Games

Post by Lamp »

mw42 wrote:
Click Here To Show Diagram Code
[go]$$Wc
$$ | O X X X O . X . O O O X . X X X O . . |
$$ | X . X . X X X O O X X X O O X O . . . |
$$ | . . . X . . . X O O . X X O O . O . . |
$$ | . . . . . . . . X X . X O O O O . . . |
$$ | . . . X . . . X . , X . X X O X O O . |
$$ | . . . X . . . . X X O O X X X X X O . |
$$ | . . . . . . . X O O 7 4 O 1 2 . . X O |
$$ | . . . . . . . . 8 . 3 5 . 6 . . . X . |
$$ +---------------------------------------+[/go]


EDIT: Also, have a look at this tsumego: http://eidogo.com/?game=1Lc8jeHa#1Lc8jeHa. The situation is similar, but black can live.


What if white plays 3 at 6?
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jts
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Re: Problem from One of my KGS Games

Post by jts »

Lamp wrote:
mw42 wrote:
Click Here To Show Diagram Code
[go]$$Wc
$$ | O X X X O . X . O O O X . X X X O . . |
$$ | X . X . X X X O O X X X O O X O . . . |
$$ | . . . X . . . X O O . X X O O . O . . |
$$ | . . . . . . . . X X . X O O O O . . . |
$$ | . . . X . . . X . , X . X X O X O O . |
$$ | . . . X . . . . X X O O X X X X X O . |
$$ | . . . . . . . X O O 7 4 O 1 2 . . X O |
$$ | . . . . . . . . 8 . 3 5 . 6 . . . X . |
$$ +---------------------------------------+[/go]


EDIT: Also, have a look at this tsumego: http://eidogo.com/?game=1Lc8jeHa#1Lc8jeHa. The situation is similar, but black can live.


What if white plays 3 at 6?

4 at 5 works, right?
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Lamp
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Re: Problem from One of my KGS Games

Post by Lamp »

jts wrote:
Lamp wrote:
mw42 wrote:
Click Here To Show Diagram Code
[go]$$Wc
$$ | O X X X O . X . O O O X . X X X O . . |
$$ | X . X . X X X O O X X X O O X O . . . |
$$ | . . . X . . . X O O . X X O O . O . . |
$$ | . . . . . . . . X X . X O O O O . . . |
$$ | . . . X . . . X . , X . X X O X O O . |
$$ | . . . X . . . . X X O O X X X X X O . |
$$ | . . . . . . . X O O . 4 O 1 2 . . X O |
$$ | . . . . . . . . 8 . 3 5 . 6 . . . X . |
$$ +---------------------------------------+[/go]


EDIT: Also, have a look at this tsumego: http://eidogo.com/?game=1Lc8jeHa#1Lc8jeHa. The situation is similar, but black can live.


What if white plays 3 at 6?

4 at 5 works, right?


It's hard for me to prove.

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


There are a lot of variations from here. And maybe 5 (or 6) wasn't correct anyway.

Edit: After looking at this some more, I think white is still dead.
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jts
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Re: Problem from One of my KGS Games

Post by jts »

B looks fine to me, but I must be misreading horribly since I can't even see where the ko you mention would come from.

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


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


Four libs to three after W captures, no?
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Dusk Eagle
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Re: Problem from One of my KGS Games

Post by Dusk Eagle »

That's hard to read though. This is simpler:

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

White has only two liberties and can't do a thing about it.
We don't know who we are; we don't know where we are.
Each of us woke up one moment and here we were in the darkness.
We're nameless things with no memory; no knowledge of what went before,
No understanding of what is now, no knowledge of what will be.
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Lamp
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Re: Problem from One of my KGS Games

Post by Lamp »

jts wrote:B looks fine to me, but I must be misreading horribly since I can't even see where the ko you mention would come from.

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


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


Four libs to three after W captures, no?


The ko came from me overthinking the problem :) Somewhere in the middle of the sequence I was playing w H1 and then b G1. Obviously b would play G2 though.

I guess the best white can do is take sente to play somewhere else, and then later come back and get a ton of ko threats out of the position by threatening to live.
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