Xuanxuan Qijing Problem 10: Black to play: ko or kill
玄玄棋经 · Problem 10 of 347 · Under the stones
Start with the forcing moves. Then watch the points that captured stones leave empty: they can be played again.
How to solve it
Black starts with the atari at D18, which forces White to connect at E17, and then descends to C19.
White's best defence is F19. Black plays F15, and White throws in at D19 to make a ko.
If White defends at E19 instead, Black still plays F15. White can capture four black stones with D19 and A19, but Black plays back under the stones at C18 and White dies.
Main line
- 1. Black D18
- 2. White E17
- 3. Black C19
- 4. White F19
- 5. Black F15
Solution checked against Sensei's Library.
Play it out on the board
Place the stones yourself and see the refutation when you miss. All the Xuanxuan Qijing problems as quick lessons.