Marc: Black to live. The book gives 1 as the correct answer. However, if black plays a instead of 1 the group is still alive plus black saves the stone below a.
Shaydwyrm: A play at allows white to play at , creating a direct ko as shown below.
Shaydwyrm: White throws in a stone at to create a shortage of liberties. Now black has to capture at and a direct ko commences.