: ( 648bb)
Black continues with the Main Semeai.

:
White is bound to follow Black with the Main Semeai.

She does not want to lose another move in the Main Semeai, because this would be equivalent to losing not only the Capture Variation, but also the Semeai Variation.

///:

:
This is the moment, when Black plays his oki into White's four-point nakade.

Semeai Variation:

:
White will choose the Semeai Variation.

:
Black connects the hanezeki's tail.

...

: (A 648be)
Black's large group at the right has four liberties left, so this is the right moment to capture White's single stone at the upper edge. The correct timing of this move is very important.

He must not continue with the usual course of the Semeai Variation, instead.

:
White's wedge is her strongest move now.

: (A 648bf; B 648bg)
Black's atari is the only move.

Connecting with , or giving atari with at the upper edge, instead, will be a grave mistake.

:
White starts a ko fight here.

She might simplify the issue by connecting with , achieving the same final score as herein.
Giving atari with , instead, will result in a change in the order of moves.

:
Black has to fight the ko.

Retreating with , instead, will be one point worse overall, as we have already seen in the subvariation above.

:
White uses her block at the upper edge as a ko threat.

: (186 648bh)
Black has to answer locally.

If he connected at , instead, White would gain decisively.

:
From here on, Black uses his moves in the hanezeki as ko threats.

:
White if forced to follow Black locally.

If she captured Black's group at the left with , instead, Black's large group at the right would survive the following semeai in return. White would lose the game by about 15 points.

Ko: ;

:
Alternatively, White could continue at the right with , and play this sequence at the left later.

:
White connects.

Answering at , , or , instead, will not affect the outcome of the game

:
Eventually, Black ends the ko fight in the left centre by connecting.

Semeai Variation:

Compared to the superordinate variation ...

• Black's cumulated gain at the upper edge is two points.
• Black lost two points of territory in the left centre.
• Black gained another point of territory in the lower left centre.

In total, Black gained one point.

White + 3 => White + 2

///:

Capture Variation:

:
White captures the hanezeki's tail.

...

...

:
White has sente to connect her single stone at the upper edge.

:
White is free to play any endgame move (especially her connection at the upper edge) earlier in the game, i.e. before her decision point. However, in any case she would lose another Main Semeai Liberty.
Black, on his side, would continue with the Main Semeai, heading for a large win in the Semeai Variation. White could not destroy more than the two marked points of Black territory in the left centre (), reaching a maximum score of Black + 1 for the Capture Variation.

Capture Variation:

Compared to the superordinate variation ...

• Black lost one point of territory in the left centre.
• Black gained another point of territory in the lower left centre.

In total, gains and losses compensate for each other.

Black + 3 => Black + 3