Xuanxuan Qijing Problem 51: White to play and kill
玄玄棋经 · Problem 51 of 347 · Placement on the 1-2 point
Black's corner has no outside liberties. That matters: look for the placement that kills outright where other moves only get a ko.
How to solve it
Black's corner has no outside liberties, and that makes a clean kill possible. White plays A18, the 1-2 point.
Black has to answer at A17 to keep enough eye space, and White extends to B18. The space at C17 is now useless to Black because of the atari at A16, so the corner is as good as dead. If Black tries E19, White makes an eye in the corner with C19 and wins the capturing race.
Starting with B18 or A17 gets only a ko, which is not the best result here. After B19 or C18, Black plays B18 and lives.
Main line
- 1. White A18
- 2. Black A17
- 3. White B18
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.