Beginner Exercise 257 / Solution

Black lives again  

togo: This loses White two stones and one ko-threat compared to on .

xela: This might look like a ko, but actually there is no way for white to put black into atari, so black is unconditionally alive in this diagram, and the two white stones will be removed as prisoners at the end of the game. Black shouldn't play any more moves in this position. I think "loses two stones" means "loses two points": in the first diagram on this page, black has 5 points of territory (counting the two white prisoners), whereas this diagram gives black 7 points.

... and again  

togo: This gets one ko-threat less for White than on .

Failure  

This is a ten-thousand year ko.