Gokyo Shumyo, Section 1, Problem 55 / Solution

[Diagram]
Main line  

White forces with W1 and W3 (the order of which is important) then with W5 threatens to make a second eye: Black can't make it false at the marked point, because White will push through at a and take two stones. So he plays B6, upon which White connects at W7.



Now at first sight, the shape is one of a dead group: a three point big eye, and a false eye at the top.

[Diagram]
Continuation  

Surprisingly enough, White captures with W1 and W3, making miai of replaying under the black+circle stones!! For reference ...

[Diagram]
Continuation  

When Black throws in, White makes two eyes at W2, sacrificing three stones at the top.


There are many opportunities for White to go wrong. Let's analyze some:

(To be continued - please contribute if you want.)


[Diagram]
Failure at 9  

At W9, if White plays W1 instead of a, Black answers at B2 to keep White down to one eye. If next White captures two stones at a, he throws in at black+circle. White should capture simultaneously to make miai of Black's answers. The order of a and W1 (W9 and White 11) is important.


[Diagram]
Failure at 7  

If White plays W7 at W1 here (instead of connecting at B2) Black captures at B2 and the miai are destroyed.


[Diagram]
Failure at 5  

White has now one big eye almost filled with three stones. There is no threat in a.


[Diagram]
Failure at 3  

If White changes the order of W3 and W5, Black can answer at B6 and make it ko with B8.


[Diagram]
Order of 3 and 5 - variation at 4  

In the main line, White hasn't yet exchanged b for W5, so when she plays atari at W3, and B4 captures, W5 makes miai of a and b.


If the order of W1 and W3 didn't matter, then either one of the answers would be different.

[Diagram]
Variation - order of 1 and 3  

Suppose w3 is not answered at a; then W5 makes life.

[Diagram]
Variation - order of 1 and 3  

But Black can answer W1 at B2, then W3 at B4 as in this diagram. Next, White comes one move too late: after W8, a and b are miai.


Finally, what if White ataris from the other side ?

[Diagram]
Variation at 1  

I thought, well, now Black can destroy the eye with B6, since the aji now works against White: B8 is atari. But ...

[Diagram]
Variation at 1  

... the capture makes miai of a and b. So ?


Problem 56


Gokyo Shumyo, Section 1, Problem 55 / Solution last edited by CharlesMatthews on July 1, 2003 - 10:10
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