Gokyo Seimyo Volume 3 Problem 13 / Attempts

Necessary forcing move  

White should force with 1 first. Black must choose a, b, or c to avoid immediately sacrificing the two stones in the corner.

Black loses 2 stones  

After the sequence to 4 black is short of liberties, and must give up at least two stones in the corner. Black does get sente here, and this is the best he can do.

Black loses 2 stones  

Normally this ko will be too serious for black to fight. Move 1 at 5 will lead to the same ko.

 

This result is 3 points better, but it is gote, and sente will usually be worth more.