: ( 145)
Black plays from below first.

:
Simple, and sufficient for White.

:
Black could play at , instead, but would not get rid of his difficulties in approaching White's group from the left.

:
The first step to take White's disturbing stones off the board.

:
White follows the "usual" path to a "late" ko.

: (131 147)
It will not help Black to occupy a shared liberty, at , instead.

Ko:

:
White is able to play a protective move on the left side, pre-empting further Black ko-threats against White's left side.

:
Black's last valid, but suicidal ko-threat.
White's centre group has four liberties left (and White has not played at yet), so is no valid ko-threat.

:
White wins the semeai by one move.