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advanced yose problem
http://www.lifein19x19.com/viewtopic.php?f=10&t=10552
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Author:  macelee [ Sun Jul 13, 2014 6:15 am ]
Post subject:  advanced yose problem

Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . 2 O X . . . . |
$$ | . . O . . O . O O X X . O X . . O . . |
$$ | . X . O . . . O . O . . O X . X . . . |
$$ | . . . X O . X O . O . O X . . . X X . |
$$ | . X X X O X X O . O . . . . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O , O O X X O X . . . X . , O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . 1 O O O O . O . . O . O . . . . |
$$ +---------------------------------------+[/go]


Taken from this pro game: http://www.go4go.net/go/games/sgfview/76

White ignores the atari. What's the value of :w2:? What's the value of capturing the 13 stones?

Author:  EdLee [ Sun Jul 13, 2014 11:03 am ]
Post subject: 

If W replies to :b1: atari, this is forced ?
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . 3 O X . . . . |
$$ | . . O . . O . O O X X 5 O X . . O . . |
$$ | . X . O . . . O . O . 4 O X . X . . . |
$$ | . . . X O . X O . O . O X . . . X X . |
$$ | . X X X O X X O . O . . . . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O , O O X X O X . . . X . , O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . 1 O O O O 2 O . . O . O . . . . |
$$ +---------------------------------------+[/go]

If B captures with :b3:, it seems to be about 26 points gote ?
Then W has miai of (a) sente, and (b)... ?
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . . . . . . X . . . 2 O X . . . . |
$$ | . b O . . O . O O X X . O X . . O . . |
$$ | . X . O . . . O . O . 6 O X . X . . . |
$$ | . . . X O . X O . O . O X 5 . . X X . |
$$ | . X X X O X X O . O . . 4 . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O , O O X X O X . . . X . , O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . 1 O O O O 3 O . . O . O . . . . |
$$ +---------------------------------------+[/go]

Author:  ez4u [ Sun Jul 13, 2014 2:16 pm ]
Post subject:  Re:

EdLee wrote:
If W replies to :b1: atari, this is forced ?
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . 3 O X . . . . |
$$ | . . O . . O . O O X X 5 O X . . O . . |
$$ | . X . O . . . O . O . 4 O X . X . . . |
$$ | . . . X O . X O . O . O X . . . X X . |
$$ | . X X X O X X O . O . . . . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O , O O X X O X . . . X . , O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . 1 O O O O 2 O . . O . O . . . . |
$$ +---------------------------------------+[/go]

If B captures with :b3:, it seems to be about 26 points gote ?
Then W has miai of (a) sente, and (b)... ?
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . . . . . . X . . . 2 O X . . . . |
$$ | . b O . . O . O O X X . O X . . O . . |
$$ | . X . O . . . O . O . 6 O X . X . . . |
$$ | . . . X O . X O . O . O X 5 . . X X . |
$$ | . X X X O X X O . O . . 4 . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O , O O X X O X . . . X . , O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . 1 O O O O 3 O . . O . O . . . . |
$$ +---------------------------------------+[/go]

After connecting at the top White's threat is the more powerful cut below. The second atari at 'a' means Black has no good answer.
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . O O X . . . . |
$$ | . . O . . O . O O X X . O X a . O . . |
$$ | . X . O . . . O . O . . O X . X . . . |
$$ | . . . X O . X O . O . O X 1 . . X X . |
$$ | . X X X O X X O . O . . . . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O . O O X X O X . . . X . . O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X . X . O O . . . . . O X . . |
$$ | . X X X . . X . . . . . O . . . X . . |
$$ | . . X . . . X . O X . . O X X O X . . |
$$ | . . X . . X . . O . . O X X . X X . . |
$$ | . . X X . X X X O . . O X . X O . . . |
$$ | . . . X . . . . X O . . O . O . . . . |
$$ ---------------------------------------[/go]


Therefore the follow up after White connects at the bottom is also different I think. White has time to play 1 below and connect with 3 after Black captures. If Black tries to cut instead of capturing, White captures and the threat of 'a' and 'b' mean that White will win the fight.
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . 2 . . . . . |
$$ | . . . . . . . . X . . 1 X O X . . . . |
$$ | . . O . . O . O O X X 3 O X b . O . . |
$$ | . X . O . . . O . O . . O X . X . . . |
$$ | . . . X O . X O . O . O X a . . X X . |
$$ | . X X X O X X O . O . . . . . . . . . |
$$ | X . O X O . . O O O . . . . . . O X . |
$$ | . X O X X X X X O . . . . . . X O X . |
$$ | X . O O . X . X O . X . . . . X O . . |
$$ | O X O . O O X X O X . . . X . . O . . |
$$ | . O . . O . O O X X X X O X O . . . . |
$$ | . . O O X O . . X O O X X O X . . O . |
$$ | . . . X X X X . X . . O O . . . O . . |
$$ | . O O O X O X . O O . . . . . O X . . |
$$ | . X X X O O X . . . . . O . . . X . . |
$$ | . . X O O O X . O X . . O X X O X . . |
$$ | . . X O O X . . O . . O X X . X X . . |
$$ | . . X X O X X X O . . O X . X O . . . |
$$ | . . . X O O O O O O . . O . O . . . . |
$$ ---------------------------------------[/go]

Does Black have a better resource at the top?

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