Beginner Exercise 47 / Solution

Solution  

is a double threat: snapback at a and throw-in ko at b. The snapback will kill Black unconditionally, so....

Solution (continued)  

connects and starts the ko in which Black takes first at a. If White wins the ko, he captures four Black stones at b.

If Black wins the ko  

If Black wins the ko, Black lives with and .

White can't avoid ko  

Black cannot avoid the ko by connecting at , as captures all the Black stones.

Inferior for Black  

Black can also start a ko with . However, this is inferior to the solution above because White takes first (see try to get first capture in a ko).