Capturing Race Exercise 20 / Solution

Part I

Black first  

If Black plays first, then B1 ensures life of his group as well as the death of the White group. Of course, this is not too interesting.

Death in gote  

Obviously, if White plays W1, then its 10 liberties to 6 liberties, so White dies in gote.


The solution is for White to play at W1. If Black plays B2, then W3 forms something like an eye in the belly, and Black is left with only 2 liberties.


It should be clear that B2 has to be played inside his own eyespace. But how to answer B2? If counting liberties is too much a hassle, then an easy way out is to create a ko with W3.


In fact, W3 wins the capturing race. Its 5 liberties to 6 liberties, so White is one liberty ahead.

Part II


With the black+circle stone, needless to say, if Black plays first, Black wins the capturing race. It seems that if White plays first, then W1 and W3 can set up a ko.


However, B2 prevents White to create any ko. So the status of the White group is actually dead, with Black having 6 liberties and White having 5 liberties.

Actually, if the reader have noticed B2 for Part I, then there is nothing to solve for Part II. This also implies that in Part I, if Black plays first, then playing at black+circle is more likely a better move than making life, since black+circle has more influence on the outside.

Capturing Race Exercise 20 / Solution last edited by Unkx80 on October 17, 2005 - 18:50
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