: ( 222ds)
Black connects at the upper edge, securing a second eye in that area.

:
However, White is able to separate Black's troops.

: (A 222dx)
Giving atari at the top just now is essential for Black.

If Black kept this move in reserve, and played it later as a ko threat, White would ignore it.
Therefore, playing the atari at in the upper left corner, instead, would be too early.

: (B 222dz)
White has to create the eye for her centre group first.

Connecting at , instead, would be mistaken.
The game would end with "no result" (Japanese rules).

:
Black bumps at the upper edge.

Please note that Black loses a tempo in the Main Semeai by this move. However, it is badly needed to keep Black's chances in the semeai with White's centre group.

: (136 222ea)
White connects, stopping Black from cutting through at the top.

Immediately pushing with in the upper left corner, instead, would be several points worse for her.

:
Black's throw-in creates a false eye for White.

Again, Black sacrifices a tempo in the Main Semeai for keeping a decisive advantage in the Central Semeai.

:
Black has to build an eye for his own group, so matching White's.

:
White's push at the upper edge starts the ko fight in the upper left corner.

:
White recaptures.

Ko:

:
Black must give atari.

:
White occupies a liberty of Black's cut-off stones.

:
Black starts the ko fight in the upper left corner.

:
White's throw-in stops Black from connecting the ko.

Please note that it was White's push with that made this (additional) internal ko threat possible.

: ( E 222ec)
Black threatens to create a second eye in the centre for his group.

Other potential ko threats, as , or , are not available here. Choosing any of these would result in a loss of a decisive liberty at the right, resulting in White winning the Central Semeai.
Please remember that - after the exchange of , - White has a ko threat at , forcing Black to occupy an own liberty with .

However, playing at (or ) at the bottom, instead, would be a few points better for Black.
White would ignore ko threat again. Thereafter, White will choose the Semeai Variation (i.e. letting Black connect the hanezeki's tail) in the semeai between her group at the bottom and Black's large group at the right.

:
White gives atari at Black's cut-off stones in the upper left corner, so ending the ko fight.

Please confirm for yourself that White must not connect at , instead, answering Black's ko threat.
After that connection, White will be unable to win the Central Semeai, resulting in Black winning the game.

:
Black's large group at the right lives independently.

:
White starts the endgame.

She will win the final endgame ko in the upper left corner, and connect at .

White will win the game by 34 points.