( 548kl):
Black's wedge is a well-known tesuji for protecting two cutting points while successfully connecting his troops.

:
Black solidly connects at the top.

:
White captures Black's initially played stone that was intended to become a sacrifice.

:
Black also solidly connects below.

:
White continues with the usual course of a new line of play.

, :
Please note that Black destroys three points of potential White territory only.

(A 548klc)
Black could play at e.g. , and destroy an additional point of White territory in the Capture Variation, without falling prey to the Punishment Semeai.
In the Semeai Variation, however, White would gain decisively by this additional Black prisoner.

At the end of the game, White will connect the Ko in the centre with .

Capture Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the lower left corner is two points.
• White's cumulated gain in the upper left is three points.
• At the top, White gained an additional point of territory.
• In the centre, Black got one point of territory.
• White's loss in the centre is one point (no territory there, but one Black prisoner taken).

In total, gains and losses compensate for each other.

White + 1 => White + 1

Semeai Variation:

Compared to the superordinate variation, ...

• Black's cumulated loss in the lower left corner is two points.
• White's cumulated gain in the upper left is three points.
• At the top, White did not capture one Black stone, so losing one point..
• In the centre, Black got one point of territory.
• White's loss in the centre is one point (no territory there, but one Black prisoner taken).
• Black captured one White stone less in the lower left corner, so losing two points.

In total, gains and losses compensate for each other.

White + 1 => White + 1