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KanazawaProblem54

 

Kanazawa Solution 54
   

[Diagram]
Diag.: White to live

Black has a FlyingSaucerShape connected underneath to his outward stones. Still there is enough weakness for White to exploit.


[Diagram]
Diag.: Main line

After White 5, Black must capture two stones: damezumari prevents her from playing at A. White captures at B to isolate the Black one-eyed group. In spite of the MeAriMeNashi proverb (Black destroys an eye at C), White will win this race to capture (semeai) because she has much more outside liberties. Personally I prefer the theory by RichardHunter on CountingLiberties than the superficial proverb.


Later on, I will post the continuation, including the semeai, as well as some variations.




[Diagram]
Diag.: Continuation A

With respect to the main line, Black has captured two stones with 1, and White one stone with 2, and the captured stones are removed. Now suppose there is an extra stone (the marked one) to prevent White from escaping. Black has time to destroy White's eye with 3. White 4 destroys the possibility of ko and both players continue to fill each other's liberties.


[Diagram]
Diag.: Continuation AA

White 4 puts Black in atari while the White group has still 4 liberties. Of course White could have played tenuki two times and Black shouldn't have played this sequence in the first place, since it's a terrible loss of KoThreats?




[Diagram]
Diag.: Continuation B

Another option for Black is to play 1 first, creating a ko and threatening to make an eye. White calmly connects. If we exchange A and B, Black has four liberties: the two circled ones, one in the eye and the one in the ko, which White will play as an atari. Compared to this, White has 8 liberties, plus one in the ko, and she may start. So, Black will only be able to capture White if he ignores five of her kothreats while she never ignores any of his. This is a five move approach ko. Technically, White is not alive. Practically, she is.


The original diagram does not contain the marked move, so White either escapes or prevents the approach ko, and she is technically alive.

Go to Problem 55



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