Gokyo Shumyo, Section 1, Problem 12 / Solution

Main line

First move  

There is absolutely no time to expand the eyespace. White has to play at the vital point right now. And the vital point of this shape is W1.

Full line  

The points B2 and W3 are miai and after the 2-3 exchange, a and b are miai.

Why the vital point ?  

The reason that W1 is the vital point lies in the fact that White can answer the atari of B2 with W3. Without W1 in place, Black would capture three stones.



As said before, expanding the eyespace is not right. Black plays atari at B2 and after W5, Black can start a ko with B6 at B2. Life in ko is not sufficient.

Wrong (ii)  

This shape does not call for the 1-2 point. The points a and b are miai to keep White down to one eye, and Black destroys the other eye by playing B2.

Playing B2 at b also works. Black should not play the atari as in the previous diagram, because that permits ko. In fact, W1 destroys more eye shape than it makes and she dies unconditionally.

Wrong (iii)  

After W1 here, Black can kill unconditionally, without a ko. After B6, White cannot make a second eye due to shortage of liberties. If W5 at B6, B6 at W5 is a deadly eye shape destroyer.

Wrong (iv)  

W1 here leads to the same tesuji of B2 to create shortage of liberties.

First move  

W1 here doesn't work either... B2 kills immediately.


Gokyo Shumyo, Section 1, Problem 12 / Solution last edited by hnishy on January 12, 2023 - 23:51
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