(Referenced by 648dy)

: ( 648dw)
White plays her kikashi in the lower left corner.

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Black has to reply immediately.

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White blocks at the top, finally answering Black's push.

Ko: ; ; ; ; ; ; ;

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Black is forced to continue with fighting Dany's Ko.

He will be unable to win the ko, but he has to enforce White's final, and disadvantageous, ko threat in the lower left corner.

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White's final ko threat, the atari in the lower left corner, costs her one point overall.

White might consider giving atari at at the left edge, instead.
However, this ko threat would lose one tempo in the Main Semeai. Black would be able to capture and connect the ko after his ko threat in the upper right. White would be forced to play at anyway. This exchange of for would not affect the final scores.

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Black continues with the Main Semeai, no longer fighting the ko in the left centre.

Using his last ko threat in the upper right - that loses one tempo in the Main Semeai - does not make sense, as he would be unable to connect the ko - losing another tempo in the Main Semeai. He is too close to the Punishment Semeai Liberty Level.

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White has to connect the ko - sooner or later.

Black plays 1/2 reductions.

Capture Variation:

Compared to the superordinate variation ...

• Black's cumulated loss in the lower left corner is one point.
• Black destroyed an additional three points of White's territory at the top.
• Black destroyed one point of White's territory in the upper right corner.
• White destroyed one point of Black's territory in the upper left corner.
• White captured Black's single stone in the lower right, so gaining two points.

In total, gains and losses compensate for each other.

White + 1 => White + 1

Semeai Variation:

Compared to the superordinate variation ...

• Black's cumulated loss in the lower left corner is one point.
• White captured an additional four Black stones in the upper right, so gaining four points.
• Black captured an additional White stone in the upper left corner, so gaining one point.
• White captured one Black stone less in the lower right, so losing two points.
• Black captured an additional White stone in the lower left corner, so gaining two points.

In total, gains and losses compensate for each other.

White + 1 => White + 1