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Tsumego problem
http://www.lifein19x19.com/viewtopic.php?f=15&t=15723		 Page 1 of 1
Author:  Ian Butler [ Fri May 11, 2018 4:35 am ]
Post subject:  Tsumego problem
I came up with the following problem while doing some variations of corner approaches/invasions.

White to play and live. (if at all possible. I'm starting to think it's not, not even a ko for life).

Author:  Knotwilg [ Fri May 11, 2018 4:52 am ]
Post subject:  Re: Tsumego problem
I think it can. Haven't checked all options yet, but I see a clear starting move, two possible answers by Black: in one, White lives, in the other, White lives or escapes.
Author:  Ian Butler [ Sun May 13, 2018 8:35 am ]
Post subject:  Re: Tsumego problem
Knotwilg wrote:
I think it can. Haven't checked all options yet, but I see a clear starting move, two possible answers by Black: in one, White lives, in the other, White lives or escapes.


Care to share the answer? :) :scratch:
Author:  Joaz Banbeck [ Sun May 13, 2018 8:48 am ]
Post subject:  Re: Tsumego problem
IMHO, white plays R3 and lives - without even needing a ko.

The R2 stone is then trapped. ( It can connect out, but then, due to the two outside white stones, it and its rescuers die. ) So one eye is at R2.

There are two options for the second eye: S4 and T1. White can get the S4 eye by playing S5, or the T1 eye by playing S2. Black cannot prevent both.
Author:  Knotwilg [ Sun May 13, 2018 9:44 am ]
Post subject:  Re: Tsumego problem
Joaz seems to be right. I thought hane at S5 was a necessary preparation (and possibly sacrifices a part) but it isn't. Here's the main line:

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


5 is crucial. Later, a is sente for b and it's seki.

Click Here To Show Diagram Code
[go]$$W White lives
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . X . . . |
$$ . . . . . . . . X 2 . |
$$ . . . . O 4 X X O . . |
$$ . . . . O X 3 O 1 O . |
$$ . . . . . X O . X 7 . |
$$ . . . . . . 6 a b 5 . |
$$ ----------------------[/go]


If Black 6 hane, White makes it easy with 7: next if Black a, White b creates shortage of liberties.
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