: ( 648db)
Black recaptures the ko in the left centre, unnecessarily.

Ko:

:
White uses her kikashi in the hanezeki, which she would have to play anyway, as a ko threat.

:
Black captures White's two stones in the lower left, erasing his shortage of liberties above.

Ko: ; ; ; ; ; ; ; ;

: (A 648dq)
Black will only use moves that belong to the Main Semeai or which are played outside the Main Semeai area as ko threats.

If will be a grave mistake to use "real" threatening moves as ko threats, instead, just because White is simply unable to connect the ko in the left centre without hurting her win in the Semeai Variation.

:
White has exhausted her ko threats, so she continues with the Main Semeai.

:
Black connects the ko in the left centre.

Black plays 0/1 reduction.

Capture Variation:

Compared to the superordinate variation ...

• White captured an additional Black stone at the top, so gaining one point.
• White lost one point of territory at the upper edge.

In total, gains and losses compensate for each other.

Black + 4 => Black + 4

Semeai Variation:

Compared to the superordinate variation ...

• White captured an additional Black stone at the top, so gaining one point.
• White lost one point of territory at the upper edge.

In total, gains and losses compensate for each other.

White + 2 => White + 2