Tsumego - dead, but WHY??

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Knotwilg
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Re: Tsumego - dead, but WHY??

Post by Knotwilg »

Click Here To Show Diagram Code
[go]$$B Black captures the white stones
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | O 1 O O X . .
$$ ---------------[/go]
In this diagram, :b1: removes the last liberty of these 7 white stones. By the rule of capture, the white stones are removed from the board.
This is what we mean by Black captures the white stones.
Click Here To Show Diagram Code
[go]$$B Black kills White
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | . 1 . O X . .
$$ ---------------[/go]
Black :b1: kills the white stones, because their eyespace is reduced to 1 eye.
Black :b1: does not capture the white stones, because they still have two liberties. In fact ...
Click Here To Show Diagram Code
[go]$$B From kill to capture - 1
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | 2 X 1 O X . .
$$ ---------------[/go]
If next Black decides to capture the white stones, reducing their liberties to 1, the maneuver needs to go in 3 steps.
After :b1: White can capture the two stones at :w2:.
Click Here To Show Diagram Code
[go]$$B From kill to capture - 2
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | O 3 4 O X . .
$$ ---------------[/go]
In the resulting position, :b3: again goes for capture, but again White can postpone being captured, by capturing herself at :w4:
Click Here To Show Diagram Code
[go]$$B From kill to capture - 3
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | O 5 O O X . .
$$ ---------------[/go]
Finally White has only one liberty left and Black :b5:captures all 7 stones, as in the very first diagram.

The whole sequence of mutual captures goes to show that Black has originally killed White, in the second diagram.

Now what did I mean with worry free?

Click Here To Show Diagram Code
[go]$$B Black kills White
$$ | . . . . . . .
$$ | . O O O O O .
$$ | X X X X X O .
$$ | O O O O X . .
$$ | . 1 . O X . .
$$ ---------------[/go]
Just like in diagram 2, Black :b1: killes White by reducing the eyespace to 1 eye. However, Black is not worry free: the black chain has 3 liberties, against White's 2 inside. Black is ahead in the capturing race but needs to be mindful of his small advantage.
Click Here To Show Diagram Code
[go]$$B Counting liberties
$$ | . . . . . . .
$$ | . O O O O O .
$$ | X X X X X O .
$$ | O O O O X 2 .
$$ | . 1 3 O X . .
$$ ---------------[/go]
When White :w2: reduces Black to 2 liberties, it's not sufficient for Black to have killed the white stones in the corner. He must set out to effectively capture them, starting with :b3: as in the above sequence of captures.

If there's anything unclear about the above, ask freely.
Uberdude
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Re: Tsumego - dead, but WHY??

Post by Uberdude »

The Go terminology is a bit counter-intuitive: I would naturally think killed/dead is a more fatal/worse outcome than captured, but in go killed stones are still on the board and not captured yet (so can still have aji). But captured stones are totally gone.
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Re: Tsumego - dead, but WHY??

Post by Tryss »

I guess that, for go players, capture is worse than death ! :rambo: never surrender ! :rambo: :lol:
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