Gokyo Shumyo, Section 1, Problem 55 / Solution

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.


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


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.)

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.

Failure at 7  

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

Failure at 5  

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

Failure at 3  

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

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.

Variation - order of 1 and 3  

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

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 ?

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 ...

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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