About Approach-Move Liberties (2009)
[ With Joachim's Ko-Semeai, the general
conditions are interchanged ]
In Joachim's Ko-Semeai, simplified here, White's sagari at is sente at any time, threatening to connect underneath to the right. So, Black must connect with a move at . Therefore, the point of cannot be counted as Black liberty. Please note that Black's eye, at , in the centre, changes the conditions on the upper edge fundamentally, as far as White's answer to the kikashi in the bamboo joint is concerned. We assume the exchange of White , Black to have been played already in the diagrams shown below. |
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If White answered Black's kikashi with the atari , there would remain two direct liberties for Black's group. |
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It does not change the matter, should Black connect his stone in atari, with here. White's answer at still leaves Black's group with two liberties, one direct liberty , and one approach-move liberty . |
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However, if White answered Black's kikashi with the solid connection , there would remain three liberties for Black's group, two direct liberties , and one approach-move liberty . This is one more liberty than with the atari, so Black will win the ko-fight (in the real problem) now. | |