( 981)

(Referenced by 229; 257)

Here we will analyse what will happen, if White connects solidly at , instead of "giving atari" at .

White's single stone on the upper edge is in atari now, so we have to shift to .

White's group has five liberties (2 * w, 3 * c), as usual. Black's group has eight liberties here (3 * c, 4 * b, k), one more liberty than usual. However, Black has lost his internal ko-threat at .

In principle, we have a situation similar to White having lost a move. So we can expect White to need three atari-ko-threats now.

@ ; Ko: ; ;

:
Black connects the hanezeki's tail with , and thereafter continues with occupying liberties. White has no chance to connect the ko at . Black threatens an atari at , so White needs atari-ko-threats.

Ko:

:
Eventually, White will need three atari-ko-threats to prevent Black from giving atari at . In the problem, it is very likely that White will be unable to get more than one.