IgoHatsuyoRonProblem23/Solution

White to play  

First, White secures an eye in sente and cut off the Black group.

Continued 1  

is the only defense to avoid an immediate ko.

Continued 2  

After reducing Black's liberties, !! is the climax.

Continued 3: Ko  

recapture at , at .

Variation  

Fujisawa, after adding some moves in the center, gives this line on "continued 2" and similar ko as above. But at a wins the capturing race.