Joachim's Ko-Semeai - Putting the Cart
Before the Horse (2013 - 2015)
12c - White Creates Another Ko-Shape
in the Centre
: In many cases, Michael Redmond's kikashi of / in the bamboo joint will not have been played, too. We will take it off the board, in order to make the following sequences more comprehensible. |
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White's group has five liberties (w, 2 * c, j, m), Black's group has seven liberties (2 * c, b, 2 * k, j, m). This is the "usual" relationship of liberties with Joachim's Ko-Semeai, but we can assume that the shared double-ko in the centre will benefit White. |
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: There is nothing that Black could to with the shared double-ko of / , which works in White's favour. Therefore, White will win the game with ease. |
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///: : Therefore, Black will play the sagari of here, instead of capturing with . |
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After the changed preparatory sequence, White's group has five liberties (2 * w, 2 * c, j), Black's group has seven liberties (2 * c, b, 2 * k, j, m). This is the "usual" relationship of liberties with Joachim's Ko-Semeai, but we can assume that the double-ko with his group (in the centre, and on the upper edge) will benefit Black. |
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After the changed preparatory sequence, White's group has five liberties (w, 2 * c, j, m), Black's group has only six liberties (2 * c, b, k, j, m). Despite the various ko-shapes, Black seems to have lost a decisive liberty. |
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: Continuing with occupying liberties, with a move at instead, will not work either. White will connect the ko at ; the shared double-ko remains in the centre, so Black will be unable to capture White's group there. |
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White's group has five liberties (2 * w, 2 * c, m), Black's group has only six liberties (2 * c, 2 * b, k, m) again. |
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@ ; Ko: ; |
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: Black's suicidal ko-threat at does not help, because - after White captured, and Black re-captured the ko - White's centre group is left with four liberties against four liberties for Black's connected group on the lower edge. It's White's turn, so she will win the semeai. |
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White's group has five liberties (2 * w, 3 * c), Black's group has seven liberties (3 * c, 2 * b, k, m). |
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: We added the beginning / of the Nakade Sequence to make this ko-threat more comprehensible. |
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White's group has five liberties (2 * w, 2 * c, j), Black's group has seven liberties (2 * c, 2 * b, k, j, m). |
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///: : If Black throws-in at , he will revert to the double-ko variation shown at the very beginning of the section, which he loses. We will show here that it is now much too late for Black to build a larger eye in the centre. At the end of this preparatory sequence, White's centre group still has an outside liberty left. Therefore, we will shift to , in order to give Black's group an additional liberty. |
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White's group has five liberties (2 * w, 3 * c), Black's group has seven liberties (3 * c, 3 * b, k). This is the "usual" relationship of liberties with Joachim's Ko-Semeai, so White will win the fight. However - seen overall - it might be advisable for White to not play her kikashi of / in the upper left corner so early. This will avoid all the surprising complications analysed above. |
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