: ( 2022MainLine)
White captures Black's four stones at the left edge, intending to start the Semeai Variation.

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Black's oki is mandatory.

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White occupies one of Black's liberties at the right.

Captering the hanezeki's tail with would revert to the Capture Variation above.

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Black's large group at the right has only six liberties left, so he is forced to connect the hanezeki's tail, in order to not falling prey to the Punishment Semeai.

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White's oki is mandatory.

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Black must reduce White's left-hand group to only one effective liberty, before he can start the attack on White's hanezeki-group in the lower right corner.

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White continues with occupying Black's liberties at the right.

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After this move at the left edge, Black is able to capture White's left-hand group in one move, should this become necessary.

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The time has come to attack White's hanezeki-group.

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Black occupies the last shared liberty in the lower right corner, so giving atari at White's group.

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White captures Black's three stone in the corner.

You will surely realise now that Black's procedure at the left edge was necessary to frustrate White's atari at Black's connected tail-group.

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White takes Black's large group in the upper right off the board.

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Black returns the favour with White's hanezeki-group.

Semeai Variation:

Compared to our 2017 solution, ...

• White destroyed two points of Black's territory in the upper right corner.
• Black captured one White stone at the upper edge, so gaining one point.
• White gained one additional point of territory at the upper edge, but lost one point of territory at the top, so the net effect is zero.
• Black captured an additional White stone in the left centre, so gaining one point.
• Black's net gain in the lower left is two points.
• White captured an additional Black stone in the right centre, so gaining one point.

In total, White lost one point.

Black + 3 => Black + 4

2022MainLine