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4 life and death problems.
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Author:  Hushfield [ Thu Aug 14, 2014 1:44 am ]
Post subject:  4 life and death problems.
For anyone that's interested: below you can find 4 problems from a lecture on life and death I recently attended at School Pink Stones.

Click Here To Show Diagram Code
[go]$$c Black to play
$$ ----------------
$$ | . . . . . . . .
$$ | . . X . . . . .
$$ | . X . . . . . .
$$ | . . X X X . . .
$$ | . . O O . X . .
$$ | . . X O . . . .
$$ | . . . O X . . .
$$ | . . O X . X . .
$$ | O O O X . . . .
$$ | X X X X . . . .
$$ | . . . . . . . .[/go]


Click Here To Show Diagram Code
[go]$$c Black to play
$$ --------------------
$$ . . X X . . . . . . |
$$ . . X O O . . O O . |
$$ . . X O . O . X O . |
$$ , . X O O O X X X X |
$$ . . . X X X . . . . |
$$ . . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]


Click Here To Show Diagram Code
[go]$$c Black to play
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . X X X X . . .
$$ | . X X O . O X . . .
$$ | X O X O . O X . . ,
$$ | . O O . . O O X . .
$$ | . O . . . O X X . .
$$ | . . . . O X X . . .
$$ ---------------------[/go]


Click Here To Show Diagram Code
[go]$$c Black to play
$$ . . . . . . . . |
$$ . . . . . X . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . O X X X . |
$$ . . X . . O X . |
$$ . . X . X O . . |
$$ . . . . O . O . |
$$ . . . . . . . . |
$$ ---------------[/go]


I'll post the answers after a few people have had a go at these problems.

If you're stuck and need a hint:
If there really is no better solution, ko might be a valid answer. But if there is a way to kill unconditionally, getting a ko represents failure. I always feel cheated when the answer to a life and death problem turns out to be ko, but it makes sense: in real games, there's no one standing next to you saying which groups can be killed unconditionally, and which ones turn into ko. Even if you get the first (few) move(s) correct, if a solution is ko and you thought it was a clean kill, you got the problem wrong. The difference between killing and starting a ko can be a big difference in a real game, after all.
Author:  Marcus [ Thu Aug 14, 2014 8:00 am ]
Post subject:  Re: 4 life and death problems.
I think I've got the first one. I keep refuting my solutions to the 2nd one. Will continue later. If anyone has a refutation of the below candidate solution, let me know. :D

Problem 1:
Click Here To Show Diagram Code
[go]$$c First Move
$$ ----------------
$$ | . . . . . . . .
$$ | . . X . . . . .
$$ | . X . . . . . .
$$ | . . X X X . . .
$$ | . . O O . X . .
$$ | . . X O . . . .
$$ | . 1 . O X . . .
$$ | . . O X . X . .
$$ | O O O X . . . .
$$ | X X X X . . . .
$$ | . . . . . . . .[/go]


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


Click Here To Show Diagram Code
[go]$$c Var 2
$$ ----------------
$$ | . . . . . . . .
$$ | . . X . . . . .
$$ | . X . . . . . .
$$ | . . X X X . . .
$$ | 3 7 O O . X . .
$$ | 6 4 C O . . . .
$$ | 5 1 2 O X . . .
$$ | . . O X . X . .
$$ | O O O X . . . .
$$ | X X X X . . . .
$$ | . . . . . . . .[/go]
Author:  Marcus [ Thu Aug 14, 2014 8:27 am ]
Post subject:  Re: 4 life and death problems.
Here's the best I can do for Problem 2:

All I could force was ko. First variation was what I thought would work, second is the better W defense:

Click Here To Show Diagram Code
[go]$$c W dies here, so see next variation ...
$$ --------------------
$$ . . X X 6 2 4 8 7 . |
$$ . . X O O 5 1 O O 9 |
$$ . . X O . O 3 X O . |
$$ , . X O O O X X X X |
$$ . . . X X X . . . . |
$$ . . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]


Click Here To Show Diagram Code
[go]$$c Ko?
$$ --------------------
$$ . . X X 6 2 4 . 7 . |
$$ . . X O O 5 1 O O 9 |
$$ . . X O . O 3 X O 8 |
$$ , . X O O O X X X X |
$$ . . . X X X . . . . |
$$ . . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]
Author:  Marcus [ Thu Aug 14, 2014 8:47 am ]
Post subject:  Re: 4 life and death problems.
Problem 3:

Click Here To Show Diagram Code
[go]$$c First Move
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . X X X X . . .
$$ | . X X O . O X . . .
$$ | X O X O . O X . . ,
$$ | . O O . . O O X . .
$$ | . O . 1 . O X X . .
$$ | . . . . O X X . . .
$$ ---------------------[/go]


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


Click Here To Show Diagram Code
[go]$$c Var 2 - :b11: at :bc:
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . X X X X . . .
$$ | 0 X X O 9 O X . . .
$$ | B O X O . O X . . ,
$$ | 7 O O 2 6 O O X . .
$$ | 8 O . 1 3 O X X . .
$$ | . . 4 5 C X X . . .
$$ ---------------------[/go]


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


Click Here To Show Diagram Code
[go]$$c Var 4
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . X X X X . . .
$$ | . X X O 2 O X . . .
$$ | X O X O . O X . . ,
$$ | . O O 4 6 O O X . .
$$ | . O . 1 5 O X X . .
$$ | . 7 . 3 C X X . . .
$$ ---------------------[/go]
Author:  drmwc [ Sat Aug 16, 2014 3:33 am ]
Post subject:  Re: 4 life and death problems.
Number 4:

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


Black kills through a double ko.
Author:  cornucopia [ Sat Aug 16, 2014 8:00 pm ]
Post subject:  Re: 4 life and death problems.
Thanks Hushfield, they look really interesting! I'm going to take them to the GGG studygroup tomorrow! I'll keep you posted on the achieved results :mrgreen:
Author:  Hushfield [ Mon Aug 18, 2014 12:05 am ]
Post subject:  Re: 4 life and death problems.
You can find the solutions below:

Problem 1:
Click Here To Show Diagram Code
[go]$$c Black kills unconditionally
$$ ----------------
$$ | . . . . . . . .
$$ | . . X . . . . .
$$ | . X . . . . . .
$$ | . . X X X . . .
$$ | 5 . O O . X . .
$$ | . 2 X O . . . .
$$ | 3 1 4 O X . . .
$$ | . . O X . X . .
$$ | O O O X . . . .
$$ | X X X X . . . .
$$ | . . . . . . . .[/go]
Problem 2:
Click Here To Show Diagram Code
[go]$$c Black can get a ko
$$ --------------------
$$ . . X X 4 3 6 7 8 . |
$$ . . X O O . 1 O O . |
$$ . . X O . O 2 X O 5 |
$$ , . X O O O X X X X |
$$ . . . X X X . . . . |
$$ . . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]
Problem 3:
Click Here To Show Diagram Code
[go]$$c Black can get a ko
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . . X X X X . . .
$$ | . X X O . O X . . .
$$ | X O X O . O X . . ,
$$ | . O O . . O O X . .
$$ | 7 O 6 1 3 O X X . .
$$ | 8 5 4 2 O X X . . .
$$ ---------------------[/go]
Problem 4:
Click Here To Show Diagram Code
[go]$$c Black kills through double ko
$$ . . . . . . . . |
$$ . . . . . X . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . O X X X . |
$$ . . X 3 2 O X . |
$$ . . X 4 X O 7 . |
$$ . . . 1 O . O 8 |
$$ . . 5 . 9 6 . . |
$$ ---------------[/go]
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