( 986)

(Referenced by 330; 1043; 1046)

However, in this special case, White might have made a mistake by filling-in her second false eye too early, with , in exchange for Black's move at , which occupied an outside liberty of White's centre group. If we remove these two stones, ...

... White does not have any effective liberty more than before, because her false eye at f compensates for the liberty at g, ...

@ ; Ko: ; ; ;

:
... but she can use the filling-in of her false eye with as a ko-threat now.

:
Black cannot give atari at immediately, ...

:
... but needs the "usual" one external ko-threat to do so. If White takes the ko on the right with , Black will capture the central ko with a move at , so giving atari on White's centre group.