: ( 648aa)
White connects her single stone at the upper edge, instead of continuing with the Main Semeai.

White's move loses a decisive tempo in the Main Semeai, which brings Black back into the game.

:
Black is forced to continue with the Main Semeai if he does not want to repeat his grave mistake of losing a decisive Main Semeai Liberty. He captures White's two stones in the lower left.

Black is unable to play the push at the top with ; please refer to ( 648ap) for details.

:
White closes the hole at the top.

Black plays 0/1 reduction.

Capture Variation:

Compared to the superordinate variation ...

• White's cumulated gain at the upper edge is two points.
• White got an additional point of territory at the top.
• Black captured two White stones in the lower left, so gaining four points.

In total, White lost one point.

White + 2 => White + 1

Semeai Variation:

Compared to the superordinate variation ...

• White's cumulated gain at the upper edge is two points.
• White got an additional point of territory at the top.
• Black captured one White stone less in the lower left, so losing two points.

In total, White gained five points.

Black + 4 => White + 1