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Surprising endgame problem
http://prod.lifein19x19.com/viewtopic.php?f=15&t=19547		 Page 1 of 1
Author:  xela [ Thu Nov 28, 2024 4:24 pm ]
Post subject:  Surprising endgame problem
Well, at least I found it surprising...

Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . . X . . . .
$$ | . O O X O . . .
$$ | . O X O . O . .
$$ | . X X O . . . .
$$ | . . X X O O . .
$$ | . . . O . . . .
$$ +----------------[/go]

Source: https://www.101weiqi.com/q/165737/ , which says it came from the book "Lee Chang-ho’s Endgame Skills".
Author:  dust [ Sat Nov 30, 2024 3:34 am ]
Post subject:  Re: Surprising endgame problem
Just interested in what is your surprise...

I'm not sure I fully understand the problem, but is your surprise that the correct answer given by the website looks like it could generate a lot of ko treats for white - possibly something black might want to consider if another ko elsewhere on the board seems likely?
Author:  Javaness2 [ Sat Nov 30, 2024 8:31 am ]
Post subject:  Re: Surprising endgame problem
Are you supposed to play B1 to force black to throw in and thus you get to create an eye patch
Author:  dust [ Sat Nov 30, 2024 10:39 am ]
Post subject:  Re: Surprising endgame problem
Indeed - another possibility, and a Frequently Asked Question in my experience.
Author:  xela [ Sat Nov 30, 2024 6:13 pm ]
Post subject:  Re: Surprising endgame problem
dust wrote:
Just interested in what is your surprise...

At first glance I was expecting some kind of capturing race squeeze, and was trying to figure out which of A3, A2 or B1 would minimise the damage. At first glance, the solution move leaves black with three liberties against white's four. I'm surprised that not only does black not lose the capturing race this way, but in fact you can make actual territory in the corner and don't need to remove the white stones from the board.
Author:  dust [ Sat Nov 30, 2024 6:35 pm ]
Post subject:  Re: Surprising endgame problem
If Black plays C1, will White really simply reply E1?...Or will White leave the bad aji hanging of playing A3 later?

for example:

Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . . X . . . .
$$ | 8 O O X O . . .
$$ | 7 O X O . O . .
$$ | 2 X X O . . . .
$$ | 3 . X X O O . .
$$ | . 4 1 O 5 6 . .
$$ +----------------[/go]
Author:  xela [ Sun Dec 01, 2024 3:25 pm ]
Post subject:  Re: Surprising endgame problem
dust wrote:
If Black plays C1, will White really simply reply E1?

Ah, now you're surprised too :-)
dust wrote:
...Or will White leave the bad aji hanging of playing A3 later? for example:

White is dead in double ko, right?
Author:  dust [ Sun Dec 01, 2024 4:41 pm ]
Post subject:  Re: Surprising endgame problem
xela wrote:
dust wrote:
If Black plays C1, will White really simply reply E1?

Ah, now you're surprised too :-)
dust wrote:
...Or will White leave the bad aji hanging of playing A3 later? for example:

White is dead in double ko, right?


If B chooses that option...

But this is potentially quite a negative result for Black? If there's a ko on another part of the board, white has an infinite set of ko threats? Or if white is losing, white could potentially force a triple ko to avoid a loss? Black can avoid this by capturing the white stones and taking them off the board, but this takes a couple of moves and costs points.

Is this risk really worth a couple of extra points in the corner?
Author:  Knotwilg [ Tue Dec 03, 2024 4:19 am ]
Post subject:  Re: Surprising endgame problem
I think I know this one. The surprising move is :b3:

Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . . X . . . .
$$ | . O O X O . . .
$$ | a O X O . O . .
$$ | 3 X X O . . . .
$$ | 1 C X X O O . .
$$ | C 2 C O b . . .
$$ +----------------[/go]


:w2: is forced. :b3: is not intuitive but effective. If White starts at A, it's 3-3 with Black to move. If White wants to come from the outside, she needs an approach move at B.
Author:  dust [ Tue Dec 03, 2024 9:29 am ]
Post subject:  Re: Surprising endgame problem
A3 certainly looks like a vital point. I wonder if B can just play it immediately.
Author:  Harleqin [ Tue Dec 03, 2024 1:18 pm ]
Post subject:  Re: Surprising endgame problem
Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . . X . . . .
$$ | . O O X O . . .
$$ | . O X O . O . .
$$ | 3 X X O . . . .
$$ | 2 . X X O O . .
$$ | . 1 . O . . . .
$$ +----------------[/go]


This seems to work?
Author:  dust [ Tue Dec 03, 2024 1:49 pm ]
Post subject:  Re: Surprising endgame problem
Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . 7 X . . . .
$$ | . O O X O . . .
$$ | . O X O . O . .
$$ | 1 X X O . . . .
$$ | 4 . X X O O . .
$$ | . 2 3 O 5 6 . .
$$ +----------------[/go]



Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . 7 3 X . . . .
$$ | . O O X O . . .
$$ | . O X O . O . .
$$ | 1 X X O . . . .
$$ | 2 . X X O O . .
$$ | . 5 4 O 6 . . .
$$ +----------------[/go]


A3 seems to work - even if white tries to resist?

Click Here To Show Diagram Code
[go]$$Bc Black to play in the corner
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . X X . . . . .
$$ | . . . X . . . .
$$ | . O O X O . . .
$$ | . O X O . O . .
$$ | 1 X X O . . . .
$$ | 5 . X X O O . .
$$ | . 3 2 O 4 . . .
$$ +----------------[/go]


Possible outcome?
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