(Referenced by 799)

: ( 133)
White separates Black's stones.

:
But White's group on the upper edge cannot get an eye.

:
Black must secure one eye for his group in the upper right, to gain a liberty that is not shared with any White group.

Please note that - due to the potential cut with - Black cannot play the guzumi of before (= here), aiming at reducing White's corner territory, because this would erase the miai for one Black eye in the upper right (79, A). White would win the semeai now, because Black's top right group were eyeless.

:
After this move it becomes evident that Black has more territory than White, and will win.

For the sake of better illustration, we have added a few stones (, ). On the right side, a giant seki (Circular Hanezeki) is born. The White group in the centre () is eyeless. Black's group (), above, has indeed got one eye; but in contrast to the general experience with "me ari me nashi" ("one eye beats no eye"), he will not be able to capture White's eyeless group below.
You will find further details in the section "Circular Hanezeki" ( 799).

Please note that Black is able to reduce the shared hanezeki-liberties in the lower right corner from two to one (), without losing a move in the main semeai. So, the Punishment Semeai will not work here in White's favour. However, this effect depends on White's group being eyeless; so it cannot be applied on both of Joachim's semeai with ko (type 1; 225) / (type 2; 363).