: ( 648bb)
Black captures White's single stone at the upper edge.

:
White destroys Black's potential territory in the left centre.

:
Black further reduces White's territory at the top.

:
This atari is sente.

:
White created one point of territory in sente.

Black plays 0/1 reduction.

Capture Variation:

Compared to the superordinate variation ...

• Black's cumulated gain at the upper edge is three points.
• Black did not get any territory in the left centre, so losing one point.
• White got an additional point of territory in the left centre.

In total, gains and losses compensate for each other.

Black + 3 => Black + 3

Semeai Variation:

Compared to the superordinate variation ...

• Black's cumulated gain at the upper edge is three points.
• Black did not get any territory in the left centre, so losing one point.
• White got an additional point of territory in the left centre.

In total, gains and losses compensate for each other.

White + 3 => White + 3