Joachim's Ko-Semeai - Putting the Cart
Before the Horse (2013 - 2015)
7a1 - Black's Mistaken Atari from Below
(Referenced by 300) In order to further investigate Joachim's cut, we will take another pair of / stones off the board. Additionally, we will assume that White answered Black's move , closing his upper left corner, with on the left side, capturing Black's nakade stones there. Otherwise - as long as the ko-shape on the right side has not been established - Black would be able to win the Capture Variation. |
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After the cut of , Black gives atari from below. As a matter of course, Black could consider playing at . But after at , at , White would take another liberty of Black's group. Without the ko-capture, the liberty-count would be six liberties for White versus seven liberties for Black; so White would win the semeai unconditionally. |
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White has seven liberties left (4 * w, 3 * c), so she would not have captured the ko with , but occupied another liberty of Black's group, in order to win the semeai unconditionally. |
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After , Black has only eight effective liberties left, and is helpless. He cannot connect the hanezeki's tail with a move at , because White's will win the semeai with his connected group on the lower edge. If Black occupied another liberty of White's group with , White would return the favour, reducing Black below the Punishment Semeai Liberty Level, forcing Black to connect the hanezeki's tail for losing the game. |
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///: It is too late for Black to play the atari of 3 from the outside now. |
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Black is forced to destroy White's potential eye on the upper edge, while White secures an eye in the centre. |
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There are six liberties for White (3 * w, 3 * c) against seven liberties for Black (3 * c, 3 * b, k). White would not have captured the ko with , but occupied another liberty of Black's group, in order to win the semeai unconditionally. |
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