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L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 8:04 am
by rlaalswo
White to play first and live. Black has infinte ko threats, so ko is death. Seki and double ko is considered alive.
$$Bc
$$ ------------------
$$ | . . . . O X . . .
$$ | . . . . O X . . .
$$ | O . . O X X . . .
$$ | . . O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . . . . O X . . .
$$ | . . . . O X . . .
$$ | O . . O X X . . .
$$ | . . O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
$$Bc
$$ ------------------
$$ | . . . . O X . . .
$$ | . . W . O X . . .
$$ | O . . O X X . . .
$$ | . . O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . . . . O X . . .
$$ | . . W . O X . . .
$$ | O . . O X X . . .
$$ | . . O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
Above is the given solution, but I don't think it's right.
$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
It seems to result in ko or bent four in corner. Am I not right?
Re: L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 10:23 am
by EricBackus
rlaalswo wrote:White to play first and live. Black has infinte ko threats, so ko is death. Seki and double ko is considered alive.
$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
It seems to result in ko or bent four in corner. Am I not right?
I think white lives:
$$Bc a and b are miai
$$ ------------------
$$ | a 3 4 . O X . . .
$$ | . 6 W b O X . . .
$$ | O 2 5 O X X . . .
$$ | . 1 . X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc a and b are miai
$$ ------------------
$$ | a 3 4 . O X . . .
$$ | . 6 W b O X . . .
$$ | O 2 5 O X X . . .
$$ | . 1 . X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
$$Bc
$$ ------------------
$$ | . 3 4 . O X . . .
$$ | . 5 W . O X . . .
$$ | O 2 6 O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . 3 4 . O X . . .
$$ | . 5 W . O X . . .
$$ | O 2 6 O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
Re: L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 10:47 am
by jlt
Eric: and if

is at b?
Re: L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 11:19 am
by Cassandra
rlaalswo wrote:
$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . 3 . . O X . . .
$$ | . . W . O X . . .
$$ | O 2 . O X X . . .
$$ | . 1 O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
It seems to result in ko or bent four in corner. Am I not right?
$$Bc
$$ ------------------
$$ | . X . . O X . . .
$$ | . 4 O . O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | . X . . O X . . .
$$ | . 4 O . O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
The status of Bent-Four-in-the-Corner depends on the number of outside liberties!
Re: L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 4:24 pm
by EricBackus
jlt wrote:Eric: and if

is at b?
Uh...ok, nevermind.

Re: L&D problem: can white live without ko?
Posted: Mon Dec 16, 2019 5:30 pm
by rlaalswo
Cassandra wrote:The status of Bent-Four-in-the-Corner depends on the number of outside liberties!
$$Wc
$$ ------------------
$$ | 3 X 2 . O X . . .
$$ | 4 1 O . O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Wc
$$ ------------------
$$ | 3 X 2 . O X . . .
$$ | 4 1 O . O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
$$Wc
$$ ------------------
$$ | 6 X X 7 O X . . .
$$ | X O O 5 O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Wc
$$ ------------------
$$ | 6 X X 7 O X . . .
$$ | X O O 5 O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
$$Bc
$$ ------------------
$$ | 2 1 4 O O X . . .
$$ | 3 O O O O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
- Click Here To Show Diagram Code
[go]$$Bc
$$ ------------------
$$ | 2 1 4 O O X . . .
$$ | 3 O O O O X . . .
$$ | O O . O X X . . .
$$ | . X O X X . . . .
$$ | O . X X . . . . .
$$ | X X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
Got it! Thanks!