Simple life and death problem

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GammaGoPBR
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Simple life and death problem

Post by GammaGoPBR »

I've been working through Kaoru Iwamoto's "Go for Beginners", and got myself stuck on one of the life and death examples.

The problem starts like this with white to move in order to kill Black's group:
Click Here To Show Diagram Code
[go]$$W Dia. 17
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X . . X O . |
$$ . . . . . . . X . . |
$$----------[/go]
Kaoru states that the only possible move for White to kill Black is:
Click Here To Show Diagram Code
[go]$$W Dia. 17a
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X . . X O . |
$$ . . . . 1 . . X . . |
$$----------[/go]
Which is followed by:
Click Here To Show Diagram Code
[go]$$W Dia. 17b
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X . 3 X O . |
$$ . . . . 1 2 . X . . |
$$----------[/go]
That makes perfect sense to me. What I don't understand is why this is the only way to kill Black.

Why not this?
Click Here To Show Diagram Code
[go]$$W Dia. 17c
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X . 1 X O . |
$$ . . . . . . . X . . |
$$----------[/go]
If black responds by playing where white should have played, then:
Click Here To Show Diagram Code
[go]$$W Dia. 17d
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X 3 1 X O . |
$$ . . . . 2 . . X . . |
$$----------[/go]
And isn't the group still dead?

What am I missing?
tj86430
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Re: Simple life and death problem

Post by tj86430 »

GammaGoPBR wrote:
Why not this?
Click Here To Show Diagram Code
[go]$$W Dia. 17c
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X . 1 X O . |
$$ . . . . . . . X . . |
$$----------[/go]

What am I missing?
What about:
Click Here To Show Diagram Code
[go]$$W Dia. 17c
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X 2 1 X O . |
$$ . . . . . . . X . . |
$$----------[/go]
It seems to me the best white can get is seki:
Click Here To Show Diagram Code
[go]$$W Dia. 17c
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . 3 X O . |
$$ . . . O X 2 1 X O . |
$$ . . . . 4 . 5 X . . |
$$----------[/go]
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Cassandra
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Re: Simple life and death problem

Post by Cassandra »

GammaGoPBR wrote: If black responds by playing where white should have played, then:
Click Here To Show Diagram Code
[go]$$W Dia. 17d
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X 3 1 X O . |
$$ . . . . 2 . . X . . |
$$----------[/go]
And isn't the group still dead?

What am I missing?
For studying:

In the case you failed (here: to live; with 2), think about the value of the board point that has been occupied by your opponent's initial reply (here: 3). It might be the vital point (of the problem) that you should have taken beforehand.
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
Bill Spight
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Re: Simple life and death problem

Post by Bill Spight »

BTW, what is the story if White plays :w1: in this diagram?
Click Here To Show Diagram Code
[go]$$W Can Black live?
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X 1 . X O . |
$$ . . . . . . . X . . |
$$ --------------------[/go]
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Re: Simple life and death problem

Post by tj86430 »

Bill Spight wrote:BTW, what is the story if White plays :w1: in this diagram?
Click Here To Show Diagram Code
[go]$$W Can Black live?
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X . . X O . |
$$ . . . O X 1 . X O . |
$$ . . . . . . . X . . |
$$ --------------------[/go]
Isn't that also seki:
Click Here To Show Diagram Code
[go]$$W seki
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X 5 . X O . |
$$ . . . O X 1 2 X O . |
$$ . . . . 4 3 . X . . |
$$ --------------------[/go]
This doesn't work for white:
Click Here To Show Diagram Code
[go]$$W black lives
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X 6 . X O . |
$$ . . . O X 1 2 X O . |
$$ . . . . 3 4 5 X . . |
$$ --------------------[/go]
or
Click Here To Show Diagram Code
[go]$$W black lives
$$ . . . . . . . . . . |
$$ . . . O O O O O . . |
$$ . . . O X X X X O . |
$$ . . . O X 6 . X O . |
$$ . . . O X 1 2 X O . |
$$ . . . 5 3 4 . X . . |
$$ --------------------[/go]
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