: ( 648ao)
Black connects in the centre, immediately taking a liberty of White' group at the left.

: ( A 648az)
White has to play her kikashi in the hanezeki.
Please note that - in the main line here, which is not the correct one - Black has one liberty to spend after his reduction of White's territory in the upper right (for the Capture Variation).

As we know now - in conjunction with Joachim's Final Ko in the correct subvariation below - White will be one point better in the Capture Variation if she does without this kikashi.

: ( A 648bb; B 648bi; C 648bk)
White connects her single stone at the upper edge.

After this connection, Black's group in the upper right has nine Main Semeai Liberties (even assuming Dany's Sacrifice).
This implies that Black will - in principle - ignore any White move in the left centre, and go for the win in the Semeai Variation, enabled by three surplus Main Semeai Liberties.
Black has the initiative at the left side, because White is restricted to passively answer a Black moves there, if ever.

Black is comfortably ahead in the Capture Variation, so gaining two points back by refuting Dany's sacrifice in the lower left later will not really benefit White.

White's connection at the upper edge is played too early.
She has to bump in the left centre with first. This move will increase her score in the Capture Variation.

Occupying a liberty of Black's upper group in the left centre with , or playing the wedge at , instead, will result in the same final scores as herein.

:
Black is able to establish an additional point of territory in the left centre.

:
After his move, neither side can get any territory in the central area below.

:
Black secures his territory in the left centre, at the cost of one Main Semeai Liberty.

:
White chooses Dany's Sacrifice and continues with the Main Semeai.

:
Black captures White's two stones in the lower left.

Black plays 0/1 reduction.

Capture Variation:

Compared to the superordinate variation ...

• Black got an additional two points of territory in the left centre.
• Black got four points by capturing two White stones in the lower left.
• White gained two points by capturing one Black stone in the lower right.
• Black gained one point in the hanezeki.

In total, Black gained five points.

White + 1 => Black + 4

Semeai Variation:

Compared to the superordinate variation ...

• Black got an additional two points of territory in the left centre.
• Black captured two White stones at the left less, so losing four points.
• White did not capture one Black stone in the lower right, so losing two points.
• White got an additional point of territory in the hanezeki.

In total, Black lost one point.

White + 1 => White + 2