Black can start a ko by capturing the stone in the corner. Whoever plays at x wins it.

Black has 4 ko threats:

threatens to link up with Black's dead group in the corner.

threatens to bring it to life by playing at A.

threatens to kill White's group by playing at B and making a false eye.

threatens to trap three white stones with C.

White only has two ko threats:

threatens to play A to make a false eye and kill the black group there.

threatens to play at B, trapping four black stones and ruining some of his territory.

When Black takes the ko, looks like a ko threat too. But it isn't, because ...

... Black answers it by capturing the 6 stones to win the ko!!

When the stones come off the board, there's no way to follow up the threat!

back to challenge problem

UK Go Challenge home 12 November 2003