: ( 432)
This move, when compared to the path of our solution, limits White's options in the upper left corner.
: (80 473)
Thus, White cannot play at , for example. prevents a deep White intrusion into Black's corner. After the subsequent Crosscut Sequence, Black no longer needs to defend his top left corner (with a move at ), and has gained a decisive move.
(B)
474
: (
432
: (80 
473
, for example. 
), and has gained a decisive move.
