Capturing Race Exercise 8 / Solution

Black first.  

If Black first, playing at B1 captures the two white stones and the question is over.

White first.  

It is more interesting when White plays first. White W1 ataris to increase the liberties, followed by the hane at W3 to prevent Black from making two eyes in the corner. Note that White can throw in at a any time, so the eye at a has effectively only one liberty.

White first.  

The correct move is Black B4, which may be a blind spot for some. It prevents White from creating a ko there. Up to Black B8, White is unable to make the approach move at a due to a shortage of liberties. This is a typical case of a capturing race where the group that has an eye kills a group that has no eye.


White W5 and W7 here are tricky: it actually attempts to make a seki. The throw in at B8 destroys the possibility of White making an eye there, and is the only correct move. If White W7 is played at B8, Black will play at W7.


Reducing White's liberties directly at B4 in this diagram is wrong. White makes two throw ins at W5 and W7, and fights a big ko in the corner.


W5 here would be a careless mistake. Note that B8 captures three White stones, so there is no ko.

Conclusion: The two marked White stones in the question are dead.

Capturing Race Exercise 8 / Solution last edited by Unkx80 on June 22, 2006 - 11:57
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