Tsumego From Games 12 / Solution

Moves 218 to 227  

Gronk: Note: a have been exchanged...

DaveSigaty: The cut at 1 starts the fun, threatening to capture two black stones and connect to the left. When Black answers at 2, White 3 takes advantage of Black's shortage of liberties. White 5 threatens to connect by capturing two stones. Black 6 connects at 3. White 7 and 9 prevent Black from making two eyes. White 3 and 9 are two variations on the theme of shortage of liberties - a very important idea in tsumego.

Moves 228 to 230  

The final result is ko. Although Black had a lot of ko threats, White can afford to give something up in order to win the ko since the black group at the bottom will die.

Alternative for B 2  

It is worth wondering what would have happened if Black had answered White 1 with 2 instead of playing a. In this case it appears that Black can answer 3 with 4. However, White 5 renews the threat of capturing at a while at the same time threatening to play at 8 and capture three stones. Black's only chance is Black 6 but White plays atari at 7 and connects at 9. At this point White has four liberties and Black has two cutting points at a and b. White will capture some stones and live.