Joachim's Ko-Semeai - Putting the Cart
Before the Horse (2013 - 2015)
4a - White's Kikashi in the Top Left Corner
( 980) (Referenced by 152) Instead, White will exchange two pairs of / . But now, White's centre group has six effective liberties left (3 * w, 3 * c), at a moment when Black must connect the hanezeki's tail, which is a disaster for Black. So what went wrong with the transformation? Nothing, we are simply not finished yet. We can shift Black's stone , which occupied a shared liberty, to the outside of White's centre-group, to give Black's group an additional liberty. |
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Black's moved stone is at now. Additionally, we added a pair of / stones to reach the moment, when White's centre group has five effective liberties left (w, 4 * c), i.e. the moment when White will capture the ko "late". The position is similar to that of the main line, as far as the relationship of liberties is concerned. Black will need one external ko-threat to win the ko-fight. |
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: Black's atari at simultaneously reduces White's -group to only four liberties (x), less enough to lose the semeai with Black's connected group on the lower edge. So White is forced to answer locally. Additionally we have to record that it would not really help White to pre-empt Black's ko-threat on the left side, because Black has another ko-threat available, the atari at . This implies that White cannot start the ko-fight in the upper right "late", but must do so "early", to exhaust Black's ko-threats. |
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: White's -group has five liberties left, so the "slow" in the nakade is no valid ko-threat for Black. The same is true for on the upper edge, because White's centre group still has four liberties. |
: After Black's move at , it is simply no valid option for White to start the ko "late". |
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