: ( 648qa)
Black connects in the upper right.

Ko: ; ; ;

:
White pushes from above.

:
Black recaptures the ko.

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

(Referenced by 648qq; 648qs)

:
White does not have any viable ko threat left. Therefore, she connects her stone in the upper right.

:
Black connects the ko.

Black plays 0/1 reduction.

Please note that a Black move at at the upper edge would be countered by a White move at in the lower left corner (and a further move at by ). The final scores of the game would remain unaffected.

Capture Variation:

Compared to the superordinate variation, ...

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

In total, gains and losses compensate for each other.

White + 2 => White + 2

Semeai Variation:

Compared to the superordinate variation, ...

• White got an additional point of territory at the upper edge.
• Black got an additional point of territory in the left centre.
• Black captured one White stone in the left centre, so gaining one point.
• Black's cumulated gain in the lower left corner is one point.
• The net effect of the different play in the upper right is zero.

In total, Black gained four points.

White + 2 => Black + 2