: ( 648qa)
White gives atari from the outside.

Please note that this move loses a decisive tempo in the Main Semeai, and so is a grave mistake.

Ko: ; ; ; ; ;

:
Black connects.

:
The ko fight continues.

:
Black uses his connection in the right centre as a ko threat.

:
White pushes from above.

; :
Please understand these two moves as replacement for White's kikashi , in the centre, which had been played too early by us.

: (A 648qq)
In order to win the ko figth in the left centre, White has to play this disadvantageous atari in the lower left corner.

Connecting her stone in the upper right, instead, will not benefit her either.

:
Black does not have any valid ko threat left, so he captures White's single stone in the upper right.

:
White must connect the ko - sooner or later.

:
The Main Semeai continues.

Black plays 1/3 reductions.

Capture Variation:

Compared to the superordinate variation, ...

• Black did not capture one White stone in the upper left corner, so losing one point.
• Black's cumulated gain in the lower left corner is one point.
• Black got an additional point of territory in the right centre.

In total, White lost one point.

White + 2 => White + 1

Semeai Variation:

Compared to the superordinate variation, ...

• Black did not capture one White stone in the upper left corner, so losing one point.
• Black's cumulated gain in the lower left corner is one point.
• White captured one Black stone more in the right centre, so gaining two points.
• Black destroyed one point of White's territory in this area.
• Black captured one White stone more in the upper left, so gaining two points.

In total, White lost one point.

White + 2 => White + 1