: ( 536)
White has to play at first, before playing the atari of in the corner.

: (A 539)
White was able to connect at the vital point of now.

It seems to us that, with , instead of following Cheng's variation by playing sagari at top, Black could take a liberty of White's group on the left edge.

:
White's group in the upper right is left with only four liberties, so White must capture Black's centre (). She cannot further approach Black's corner group, e.g. with a move at successfully, due to Damezumari. After the "usual" sequence in the lower right corner, dissolving the hanezeki, White will use her sente to capture Black's entire upper left corner with .
Black will win by a few points, similarly to what has been shown before ( 536).

Thanks to Joachim's double-ko ( 532), this minor flaw in Cheng's analysis does not have any negative effect on the solution.